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diff --git a/41938-8.txt b/41938-8.txt deleted file mode 100644 index b6766dc..0000000 --- a/41938-8.txt +++ /dev/null @@ -1,7335 +0,0 @@ -The Project Gutenberg EBook of Principles and Practice of Fur Dressing and -Fur Dyeing, by William E. Austin - -This eBook is for the use of anyone anywhere at no cost and with -almost no restrictions whatsoever. You may copy it, give it away or -re-use it under the terms of the Project Gutenberg License included -with this eBook or online at www.gutenberg.org - - -Title: Principles and Practice of Fur Dressing and Fur Dyeing - -Author: William E. Austin - -Release Date: January 28, 2013 [EBook #41938] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK FUR DRESSING, FUR DYEING *** - - - - -Produced by Chris Curnow, Rosanna Murphy and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - -Transcriber's Note: Italic text is denoted by _underscores_ and -bold text by ~tildes~. Subscripted text is enclosed in {braces}. - - - - -FUR DYEING AND FUR DRESSING - - - - - PRINCIPLES AND PRACTICE - OF - FUR DRESSING AND FUR DYEING - - - BY - WILLIAM E. AUSTIN, B.S. - CONSULTING CHEMIST TO THE FUR INDUSTRY - - - _ILLUSTRATED_ - - - [Illustration] - - - NEW YORK - D. VAN NOSTRAND COMPANY - EIGHT WARREN STREET - 1922 - - - Copyright, 1922, by - D. VAN NOSTRAND COMPANY - - - All rights reserved, including that of translation into - foreign languages, including the Scandinavian - - - PRINTED IN THE UNITED STATES OF AMERICA - - - - -PREFACE - - -The great increase in the use of furs during the past few decades has -caused the fur dressing and dyeing industry to rise from relative -insignificance to considerable importance as a branch of applied -chemistry. The past eight years, moreover, have witnessed the virtual -transference of the leadership in the dressing and dyeing of furs from -Europe to America, and in the quality and variety of products, the -domestic industry is now in every way the equal of, and in many respects -superior to the foreign. The great bulk of American furs which formerly -were sent to Leipzig, Paris or London to be dressed and dyed, are now -being dressed and dyed in this country. - -In spite of these facts, very little is generally known about the nature -and manner of the work constituting the dressing and dyeing of furs. -Even among members of other branches of the fur trade, there is very -little accurate information on the subject. Real knowledge concerning fur -dressing and dyeing is possessed only by those actually engaged in the -industry. The interest and efforts of scientists and technologists have -been enlisted to only a small extent in the technical development of the -industry. The reason for this may be attributed to two related causes: -first, the almost monastic seclusion in which fur dressers and dyers, -particularly the latter, conducted their operations, and even to-day the -heavy cloud of mystery is being dispelled but very slowly; and second, -as a consequence of the first, the lack of any reliable literature on -the subject. Of the few books which have been written on the industry -of fur dressing and fur dyeing (all of them either German or French), -most are hopelessly out of date, or contain no trustworthy data; or, -if they do have real merit, they cannot be obtained. Numerous articles -in the technical journals are of interest, but they contain very little -information of value. - -This work is intended for a two-fold purpose: first, that it may serve as -a text-book for those who expect to make fur dressing and dyeing their -vocation. The fundamental principles upon which the industry is based -are discussed in the light of the most recent chemical and technical -developments, and the most important operations are treated fully and -systematically, and are illustrated with practical examples. - -Secondly, as a practical handbook for the worker in the fur dressing and -dyeing plant. The latest factory processes and methods are described, and -numerous working formulas given. The formulas are all such as have been -successfully used on a large scale, and give satisfactory results when -applied under the proper conditions. - -In addition, it is believed that the book will prove of interest to -chemists and other students of industrial chemistry, since it will be an -introduction into a field of applied chemistry, about which very little -is known to those outside of the industry. - -Thanks are due to Dr. L. A. Hausman, of Cornell University, for material -used in Chapter II; to Dr. E. Lesser of the American Dyewood Company, -for information and assistance on the subject of Vegetable Dyes; to the -Gaskill Chemical Corp., American Aniline Products, Inc., the Cassella -Company, and the Franklin Import & Export Co., for information about -their products in connection with the chapter on Oxidation Colors; to F. -Blattner, Fletcher Works, Inc., S. M. Jacoby Co., Proctor & Schwartz, -Inc., Reliable Machine Works, Seneca Machine & Tool Co., Inc., and the -Turner Tanning Machinery Co., for the use of the cuts of the various -machines. - - WILLIAM E. AUSTIN. - -NEW YORK, May, 1922. - - - - -TABLE OF CONTENTS - - - CHAPTER PAGE - - PREFACE - - I. FURS AND THEIR CHARACTERISTICS 1 - - Introductory. Knowledge of furs essential. Definitions. - Differences in furs of various animals. Effect of climate - on furs. Effect of age and season on furs. Durability and - relative weights of furs. Description of important furs. - - - II. STRUCTURE OF FUR 21 - - The skin. The hair. Under-hair and top-hair. Chemical - composition of furs. Action of chemicals on the skin. - Action of chemicals on the hair. - - - III. FUR DRESSING: INTRODUCTORY AND HISTORICAL 29 - - Objects of fur dressing. Origin of fur dressing. Use - of fats. Use of salt and alum. Use of the tannins. Early - organizations of the fur workers. Modern organizations - of the fur dressing industry. - - - IV. FUR DRESSING: PRELIMINARY OPERATIONS 36 - - Flat skins and cased skins. Herbivorous and carnivorous - fur animals. Beaming or scraping. Softening the skins. - Cleaning; hydro-extracting. Fleshing. - - - V. FUR DRESSING: TANNING METHODS 45 - - Nature of the tanning process. Chief tanning methods. - Comparison of the tanning methods. Effect of dyeing - operations on the dressing. - - - VI. FUR DRESSING: DRYING AND FINISHING 71 - - Importance of the drying process. Methods of drying. - A modern type of drying device. Oiling. Staking or - stretching. Beating and combing. Drum-cleaning. Unhairing - and shearing. - - - VII. WATER IN FUR DRESSING AND DYEING 85 - - Importance of water in dressing and dyeing. Water - suitable for dressing and dyeing. Soft water and hard - water. Effects of hardness in water. - - - VIII. FUR DYEING: INTRODUCTORY AND HISTORICAL 90 - - Purposes of fur dyeing. Improvement of furs faulty in - color. Production of a uniform shade on furs. Dyeing furs - to obtain novel effects. Imitation of valuable furs on - cheaper skins. Difficulties due to the hair. Difficulties - due to the leather. - - - IX. FUR DYEING: GENERAL METHODS 98 - - Two methods of dyeing furs. Development of the dyeing - methods. The brush process. The dip process. Blending. - Drying and finishing the dyed furs. - - - X. FUR DYEING: KILLING THE FURS 106 - - Nature of the killing process. Old killing formulas. - Modern killing agents. Procedure of killing. Killing with - soda. Killing with lime. Killing with caustic soda. - - - XI. FUR DYEING: MORDANTS 114 - - Nature of mordanting. Purposes of mordanting. Theory - of mordants. Procedure of mordanting. Aluminum mordants. - Iron mordants. Copper mordants. Chromium mordants. Tin - mordants. Alkaline mordants. - - - XII. FUR DYEING: MINERAL COLORS USED ON FURS 125 - - Mineral chemicals as fur dyes. Lead dyes. Potassium - permanganate as a dye. Other mineral dyes. - - - XIII. FUR DYEING: VEGETABLE DYES 128 - - Wood dyes. Old dye formulas. The vegetable dye - materials. The tannin substances. Logwood. Fustic. - Brazilwood. Other vegetable dyes. Characteristics of the - wood dyes. Application of the vegetable dyes. Application - by the brush process. Application by the dip process. - Production of shades other than black. - - - XIV. FUR DYEING: ANILINE BLACK 144 - - Dyeing of seal. Nature and history of Aniline Black. - Chemistry of the Aniline Black process. Three stages - in the formation of Aniline Black. Methods of applying - Aniline Black. One-bath Aniline Black. Oxidation Aniline - Black. Diphenyl Black. Aniline Black by Green's process. - Aniline Black by the dip method. - - - XV. FUR DYEING: OXIDATION COLORS 155 - - The original patents. The first Oxidation fur dyes. - Early difficulties. Solution of the difficulties. - Progress with the Oxidation dyes. Para-phenylene-diamine: - a typical Oxidation color. Range of shades obtainable. - Mordants. Procedure in dyeing. Typical formulas. - Combination of Oxidation colors with other dyes. - - - XVI. FUR DYEING: COAL TAR DYES 171 - - Use of coal tar dyes. Basic colors. Acid colors; dyeing - at higher temperatures. Chrome colors. Vat dyes. - - - XVII. BLEACHING OF FURS 179 - - Purpose of bleaching. Steps in the bleaching process. - Methods of bleaching. Bleaching materials with reducing - action. Bleaching materials with oxidizing action. - Blueing. - - - BIBLIOGRAPHY 185 - - - - -FUR DRESSING AND FUR DYEING - - - - -CHAPTER I - -FURS AND THEIR CHARACTERISTICS - - -Furs have in general two uses: as the goods which constitute the basis of -the furrier's art, and as the source of material for the hat manufacturer. -In the latter case, only the hair part of the fur is utilized in the hat -trade for the production of felt, the skin being either made into leather, -or used as the raw material for making high-grade glue and gelatine. It -is the furrier, therefore, who uses the great bulk of furs, and requires -them to be dressed and dyed. - -In discussing the dressing and the dyeing of furs, there are, broadly -speaking, two fundamental subjects to be considered: first, the raw -materials employed, which are, of course, the skins or pelts as they -come from the trapper. (Other substances used in fur dressing and dyeing -are accessories, and will be studied in connection with the processes.) -Second, all those operations, physical and chemical, manual and -mechanical, to which the raw skins have to be subjected in order to obtain -the finished fur, ready for use by the furrier. - -Next to the inherent qualities of the fur skin, the future value of a -fur in a manufactured garment depends largely on the dressing and dyeing -it receives. It is in these operations that the beauty of the fur can -be brought out to its fullest degree, and if possible, enhanced, or the -attractive features can be marred or destroyed, and the fur rendered -quite worthless. Therefore, it is quite essential for the fur dresser -and the fur dyer in addition to the technical knowledge and experience -which are the fundamental requisites of the industry, also to have more -than a superficial familiarity with the various kinds of furs. In fact, -an accurate knowledge of the nature and chief characteristics of furs -in general, and of the individual classes, in particular, is almost -indispensable to obtain the best results. The habits and habitats of -the various fur-bearing animals are factors which largely determine the -constitution of the fur, and the nature of the skin. There are as many -different kinds of fur hair, with as many different kinds of skin bearing -the hair, as there are classes of furs. The methods of dressing, and -often, if the furs are to be dyed, the manner of dyeing, are determined -by the nature of these component parts of furs. Various chemicals affect -furs in widely different ways. The divergence with regard to the physical -and chemical properties of the classes of furs is such as to make almost -imperative a detailed knowledge of the typical members of the many groups -of commercial furs. - -To be sure, there are many engaged in the dressing and dyeing of furs, -who never made a formal study of this phase of the industry, but acquired -their knowledge empirically, and are apparently quite successful. It -must not be denied, that practise and experience, as in every field of -enterprise, are essential to obtaining the best results. But the time and -cost of acquiring this precious experience can be considerably reduced by -systematically studying the important characteristics and properties of -furs. These will be treated briefly, but in sufficient detail to form a -basis for discussing the operations of dressing and dyeing. - -Fur-bearing animals are mammals whose skins are used in the manufacture of -fur garments and other fur wearing apparel. The skin, when it is removed -from the animal is called a pelt, or sometimes, in the case of large -animals, a hide. The pelt, after having been dressed and dyed, is called -a fur, the skin part being referred to as the leather, and the hair as the -pelage. However, this terminology is not strictly adhered to in practise, -and the various terms are often employed interchangeably. - -The various fur-bearing animals differ considerably in the characteristics -of the furs they yield. With few exceptions, notably beaver and Alaska red -fox, the depth of shade increases as the habitat of the animal species is -nearer the equatorial regions. There seems to be a direct relationship -between the intensity of color of the pelt, and the distance from, or -proximity to the polar, or the torrid regions. Thus, white mammals, such -as polar bear, ermine, white or Siberian hare, are found only in the -northern lands. An exception is the sheep, which, due to its domestic -nature, can be found in almost all parts of the civilized world. Tropical -animals on transportation to colder climates, have been known to become -lighter-haired when adapted to their new environment. The skins of animals -living in dense woods or forests, are generally of a deeper color than -in animals living in more open territory. As a general rule, fur-bearing -animals have darker hair on the back than on the sides and belly. The -badger, hamster, ratel and panda are exceptions having the darker hair on -the belly and sides, and the lighter hair on the back. With regard to the -intensity of color, the skunk has the blackest fur, although some domestic -cats are also quite black. Other animals whose fur is nearly black, are -the black bear, and the black fox, which is a variety of the silver fox, -but the color is often of a brownish shade. The colors which predominate -among animals of the fur-bearing variety, are white, black, brown, and -grey. Less common are yellow shades, and those known as blue. - -The quality of the fur on all mammals improves with cold, and animals -living at greater altitudes, with correspondingly lower temperatures, -have thicker and finer hair than those living nearer sea-level. A cold -winter generally produces fur of high quality and fine color, a mild -winter may cause the hair to be inferior. In all climates, animals found -in dense woods, have fur which is deeper, silkier, thicker, and glossier -than that of animals living in the open. Animals inhabiting inland lakes -and rivers, have finer and softer hair than those living near the coast -or land exposed to sea winds. In general, the hair of animals of the cold -regions is short, fine, soft, and downy, while the hair of animals of -warmer lands, is longer, stiffer, and harder. - -Both the quality and color of the fur vary with the age of the animal. -The young usually have a thicker coat of fur than adults, but the hair is -too soft, and the skin generally too tender to be fit for use. In certain -cases, particularly the baby lambs, very young skins are especially -prized, and eagerly sought, but extraordinary care has to be exercised in -working with them. Fur is at its best when the animal is between one and -two years old. After this age, the fur becomes coarse and scraggy. The -animal attains its fullest growth of hair usually in the height of winter, -and the fur is best between then and very early spring. Before mid-winter -the hair is short and thin, and in the spring it begins to shed, and will -continue to fall out even in the dressed fur. The color of the hair also -becomes lighter with age, and the new growth which generally comes in the -fall is darker than the old coat. - -Different members of the same species, will, other factors such as age -and season being equal, vary as to color and quality. There may even be -several different color phases of the same species of animal, such as the -cross fox and the silver fox, both of which are of the same genus as the -red fox; black muskrats are of the same class as the brown variety, etc. -The individual pelt likewise presents many variations in color and nature -of the hair. In some parts, the hair is thicker and softer than others, -and the color varies in intensity and shade throughout the different -sections of the skin. - -Furs do not have differences confined to the hair part only; the leather -also presents considerable variation among the different fur-bearing -animals, especially in regard to the weight and thickness. The durability -of furs, relatively considered under similar conditions of wear, also -varies widely. In the following table the relative durability of dressed -furs, and in certain instances also dyed furs, otter being taken as -standard, is given, as well as the weight in ounces per square foot of -skin of these furs. - - _Name of Fur_ _Durability_ _Wt. in oz. - _Otter = 100_ per sq. ft._ - Astrachan 10 3 - Bear, brown or black 94 7 - Beaver, natural 90 4 - Beaver, plucked 85 3-7/8 - Chinchilla 15 1-1/2 - Civet cat 40 2-3/4 - Coney 20 3 - Ermine 25 1-1/4 - Fox, natural 40 3 - Fox, dyed black 25 3 - Genet 35 2-3/4 - Goat 15 4-1/8 - Hare 05 2-1/4 - Krimmer 60 3 - Kolinsky 25 3 - Leopard 75 4 - Lynx 25 2-3/4 - Marten, Baum natural 65 2-3/4 - Marten, Baum blended 45 2-3/4 - Marten, Stone natural 45 2-7/8 - Marten, Stone dyed 35 2-7/8 - Mink, natural 70 3-1/4 - Mink, dyed 35 3-1/4 - Mink, Jap 20 3 - Mole 07 1-3/4 - Muskrat 45 3-1/4 - Nutria, plucked 25 3-1/4 - Opossum, natural 37 3 - Opossum, dyed 20 3 - Opossum, Australian 40 3-1/2 - Otter, land 100 4-1/2 - Otter, sea 100 4-1/2 - Persian lamb 65 3-1/4 - Pony, Russian 35 3-1/2 - Rabbit 05 2-1/4 - Raccoon, natural 65 2-1/4 - Raccoon, dyed 50 2-1/2 - Sable 60 2-1/2 - Sable, blended 45 2-1/2 - Seal, fur 80 3-1/2 - Seal, fur dyed 70 3-1/8 - Skunk, tipped 50 2-7/8 - Squirrel, grey 20-25 1-3/4 - Wolf, natural 50 6-1/2 - Wolverine 100 7 - -In estimating the value of a fur, many factors have to be considered. -There is no one standard by which the skins are judged, each kind of -fur having its own criterion. However, the general points by which raw -furs are graded are, color, size, origin, quality and quantity of hair, -condition of leather, date or season of trapping, methods of handling, -etc. Beaver, for example, is graded as large, medium, small and cubs. -Red foxes, first, into Alaska, Labrador, and Nova Scotia, and then these -divisions are classed as large, medium and small. Skunks are graded -according to the amount of white on the skin, the less white, the more -valuable the fur. - -The qualities which make a fur desired depend first of all on the nature -of the fur itself. Pretty color, luster, thickness, softness, length, -uniformity and regular fall of the hair are the chief points to be -considered. While the leather part of the fur is of secondary importance -in the evaluation of a fur, it must possess strength, lightness of weight, -and when properly dressed, should be supple and have a certain firmness or -'feel.' The abundance or scarcity of a fur-bearing animal also determines -the value of the fur. Furs which are always comparatively rare, such as -silver fox, Russian sable, chinchilla, etc., are always highly prized. -In this connection, circumstances which tend to decrease the number of -available pelts of any particular animal, such as pestilences, gradual -extermination due to excessive trapping, prevention of trapping, by -protective laws, also affect the value of a fur. A third factor which has -an influence on the value of furs, is the prevailing style or fashion. -Many kinds of furs which are both beautiful and rare, such as Russian -sable or chinchilla, are practically unaffected by the whims of fashion. -But a fur of ordinary value may at times become so popular, that the -demand for it will cause its price to be greatly increased. Similarly, a -fur which has enjoyed a considerable vogue, may pass out of demand for a -time and consequently depreciate in value. - -A detailed description of the various furs used in commerce is not within -the scope of this work, because such an account rightly belongs in a book -on zoölogy. However, it is desirable that the reader who is interested -in the dressing and dyeing of furs should have at least a passing -acquaintance with the chief furs used in commerce, together with such of -their individual characteristics as are of importance. The figures given -are for the average dressed skin.[1] - - [1] Descriptions after W. S. Parker, Deputy Chairman, Fur Section of - London Chamber of Commerce, in Encyclopedia Britannica, 11th Ed. - -~Astrachan~, see Lambs. - -~Badger.~--2 × 1 ft. This is one of the few animals whose fur is darker -on the belly than on the back. The American sorts have coarse, thick -under-hair of a pale fawn or stone color, with a growth of longer black -and white hairs 3-4 inches long. The Japanese varieties are usually dyed -for imitation skunk. The American kind is also dyed occasionally but is -mostly used natural. Badger hair is very extensively used for 'pointing.' - -~Bear, Black.~--6 × 3 ft. Has fine, dark brown under-hair, with bright, -flowing black top-hair 4 inches long. The fur of cubs is nearly as long, -although the skins are much smaller, and the hair is finer, softer, and -lighter-pelted. The best skins are from Canada. - -~Bear, Brown.~--6 × 3 ft. Similar to the Black Bear, but more limited in -number. The color ranges from a light yellow to a rich dark brown. The -best and most valuable sorts come from the Hudson Bay territory, inferior -skins coming from Europe and Asia. - -~Bear, White.~--10 × 5 ft. This is the largest of the bears. The hair is -short and close except on the flanks, while the color ranges from white -to yellow. The best skins come from Greenland, the whitest being the most -valuable. - -~Beaver.~--3 × 2 ft. This is the largest of the rodents, and is very -widely used; formerly to a great extent in the hat trade. The under-hair -is close and of a bluish-brown hue, and nearly an inch deep. The over-hair -is coarse, bright black or reddish-brown in color, and is usually plucked -out, as the under-hair is the attractive part of the fur. The darkest -skins are the most valuable. Formerly beaver was used to dye in imitation -of seal, but more suitable furs are now used. - -~Broadtail~, see Lambs. - -~Caracul~, see Lambs. - -~Cat, Civet.~--9 × 4-1/2 inches, with short, thick and dark under-hair, -and silky, black top-hair with irregular white markings. It is similar -to the skunk, but is lighter, softer, less full, and has no disagreeable -odor. - -~Cat, House.~--18 × 9 inches. Is mostly black and dark brown, the best -skins coming from Holland. The hair is weak, coming out with the friction -of wear. In the trade, the black variety is known as genet. - -~Chinchilla.~--12 × 7 inches. This is one of the rarest and most beautiful -furs. It comes from Bolivia and Peru, where, due to the uncontrolled -trapping of the animal, it is becoming scarce, and this compelled the -governments to enact laws prohibiting the taking of chinchilla for a -certain period. The fur is of a delicate blue-grey, with black shadings, -the fur being 1 - 1-1/4 inches deep. Unfortunately, the skin is quite -perishable. - -~Chinchilla, La Plata.~--9 × 4 inches. Incorrectly called "bastard -chinchilla" in the trade. It is a similar species to the Bolivian -chinchilla, but due to the lower altitude and warmer climate of its -habitat, is smaller, with shorter and less pretty hair, the color of the -under-hair being darker, and of the top-hair less pure. It is quite as -undurable as true chinchilla. - -~Chinchillone.~--13 × 8 inches. Is also from South America. The fur is -longer, weaker, poorer and yellower than real chinchilla, but the skins -are often dyed in shades closely resembling the natural chinchilla. - -~Ermine.~--12 × 2-1/2 inches. The under-hair is short and even, with the -top-hair slightly longer. The leather is light, close in texture, and -quite durable. In mid-winter the color is pure white, except the tip of -the tail, which is usually quite black. The best skins are from Siberia. - -~Fisher.~--30 × 12 inches, with tail 12-18 inches long. It is the largest -of the marten family. The under-hair is deep, and of a dark shade, with -a fine dark, glossy and strong top-hair, 2 or more inches long. The best -skins are from Canada. The fur is something like a dark silky raccoon, -while the tail, which is very highly prized, is almost black. - -~Fitch.~--12 × 3 inches. It is of the marten species, and its common name -is polecat. The under-hair is yellow and 1/3 of an inch deep. The top-hair -is black, 1-1/2 - 1-3/4 inches long, very fine and open in growth, and not -so close as the martens. The largest and best skins are from Denmark, -Holland and Germany. The Russian skins are smaller, silkier, and are -usually dyed as a substitute for sable. - -~Fox, Blue.~--24 × 8 inches. The under-hair is thick and long, while the -top-hair is fine and not so plentiful as in other foxes. It is found in -Alaska, Hudson Bay Territory, Greenland and Archangel. Although called -blue, the color is really of a slaty or drab shade. The skins from -Archangel are more silky and of a smoky bluish color, and being scarce are -most valuable. The white foxes which are dyed a smoky blue are brilliant -and quite unlike the browner shades of the blue-fox. - -~Fox, Cross.~--20 × 7 inches. The skins generally have a pale yellow or -orange tone, with some silver points, and a darkish cross marking on the -shoulders, on account of which the animal got its name. Some are very -similar to the pale red foxes of Northwest America. The darkest and best -skins are from Labrador and Hudson Bay, those from lower latitudes being -inferior. - -~Fox, Grey.~--27 × 10 inches. Has a close dark drab under-hair, with -coarse regular, yellowish, grizzly-grey top-hair. The majority of the -skins come from Virginia and southwestern U. S. A. Those from the west -are larger and brighter-toned. - -~Fox, Kit.~--20 × 6 inches. The under-hair is short and soft, as is also -the top-hair, which is a very pale grey mixed with some yellowish-white -hairs. It is the smallest of the foxes, and is found in Canada and -northern United States. - -~Fox, Red.~--24 × 8 inches, although some kinds are larger. The under-hair -is long and soft, and the top-hair is plentiful and strong. The colors -range from pale yellow to a dark red, some being very brilliant. It -is widely found in northern America, China, Japan, and Australia. The -Kamchatka foxes are exceptionally fine and rich in quality. Farther north, -near the open sea, the fur is coarse. The skins have an extensive use, -both natural and dyed. They are dyed black in imitation of the black -fox, or these when pointed with badger or other white hair to imitate the -silver fox. - -~Fox, Silver.~--30 × 10 inches. The under-hair is close and fine, and the -top-hair, which is black to silvery, is 3 inches long. The fur on the neck -usually runs almost black, and in some cases the black extends over half -the length of the skin. When all black, it is a natural black fox, and -is exceedingly rare and high-priced. The silver fox is very valuable, the -finest wild skins coming from Labrador. The tail is always tipped white. -The majority of the silver fox pelts that reach the market today are bred -on ranches in Canada and the United States. - -~Fox, White.~--20 × 7 inches. It is usually small and inhabits the extreme -northern sections of Hudson Bay, Labrador, Greenland, and Siberia. The -Canadian are silky-haired and inclined to a creamy color, while the -Siberian are whiter and more woolly. The under-hair is generally of a -bluish-grey tone, but the top-hair in winter is usually full enough -to hide such a variation. Those skins which have under-hair that is -quite white are rare and much more expensive than the others. In summer -specimens of these species have slightly discolored coats, the shades -resembling those of the blue fox. The skins which are not perfectly white -are bleached, or if they cannot be bleached sufficiently white they are -dyed various shades of smoke color, blue-greys and also imitation blue -fox. - -~Goat.~--The size varies greatly. The European, Arabian and East Indian -varieties are used mainly for leather and wool. Many from Russia are dyed -black for rugs. The hair is brittle, with poor under-hair, and is not -durable. The Chinese export many skins in grey, black and white, made into -rugs of two skins each. Frequently the skins are dyed black or brown in -imitation of bear. - -~Hamster.~--8 × 3-1/2 inches. A destructive rodent found largely in Russia -and Germany. The fur is very flat and poor, of a yellowish-brown color, -with a little marking of black. On account of its lightness it is used -for linings; occasionally it is dyed. - -~Hare.~--24 × 9 inches. The common hare of Europe is used mostly for the -hatters' trade. The white hares of Russia, Siberia, and other northern -regions are the ones mainly used for furs. It is whitest in mid-winter, -and the fur on the flanks is longer than that on the back. The hair is -brittle and not durable, and the leather is quite as bad. Yet the skins -are used to dye imitations of more than a dozen different furs. The North -American hares are also dyed black and brown. - -~Kangaroo.~--The sizes vary greatly, the larger kinds being generally -used for making leather. The sorts used for fur are, blue kangaroo, bush -kangaroo, wallaroo, rock wallaby, swamp wallaby, and short-tailed wallaby. -Many of the swamp wallabies are dyed imitation skunk, and look quite -attractive. The colors are generally yellowish or brown, some in the swamp -variety being dark brown. The skins are quite strong. The rock wallabies -are soft and woolly, and often have a bluish tone. They are used for rugs. - -~Kolinsky.~--12 × 2-1/2 inches. It is of the marten family. The under-hair -is short and rather weak, but regular, as is also the top-hair. The color -is usually a uniform yellow. They are generally dyed in imitation of other -members of the marten family. It is very light in weight, and the best -skins are obtained from Siberia. The tails are used for artists' "sable" -brushes. - -~Lambs.~--Those of commercial interest are from South Russia, Persia, -and Afghanistan, and include Persian Lamb, Broadtail, Astrachan, Shiraz, -Bokhara, Caracul, and Krimmers. - -The _Persians_ are 18 × 9 inches, and are the finest and best. When -properly dressed and dyed they should have regular, close, bright curls, -varying from small to very large and if of equal size, regularity, -tightness and brightness, their value is inestimable. - -All the above lambs, except krimmer, are naturally a rusty black or brown, -and are in most cases dyed a jet black. Luster cannot be imparted where -naturally lacking. - -_Broadtails_, 10 × 5 inches, are the young of the Persians, killed -before the wool has had time to develop beyond the flat wavy state. They -are naturally of exceedingly light weight, and when of an even pattern -possessing a lustrous sheen are costly. The pelt, however, is too delicate -to resist hard wear. - -_Astrachan_, _Shiraz_, and _Bokhara_ lambs, 22 × 9 inches, are of -a coarser and looser curl. Caracul lambs are the very young of the -astrachan, and the finest skins are almost as effective as the broadtails, -although not so fine in texture. - -_Krimmers_, 24 × 10 inches are grey lambs obtained from Crimea. They are -of a similar nature to the caraculs, but looser in curl, and ranging in -color from a very light to a dark grey, the best being pale bluish-greys. - -_Slink lambs_ come from South America and China. The South American are -very small, and generally those are still-born. They have a particularly -thin pelt, with very close wool of minute curls. The Chinese sorts are -much larger. - -~Leopard.~--3 × 6 feet long. There are several kinds, the chief being the -snow leopard or ounce, Chinese, Bengal, Persian, East Indian, and African. -The first variety inhabits the Himalayas, and has a deep, soft fur, quite -long as compared with the Bengal sort. The colors are pale orange and -white with dark markings. The Chinese are of a medium orange-brown color -and full in fur. The East Indian are less full and not so dark; the Bengal -are dark and medium in color with short, hard hair. The African are small, -with pale lemon-colored ground, and very closely marked with black spots. - -~Lynx.~--45 × 20 inches. The under-hair is thinner than in the fox, but -the top-hair is fine, silky and flowing, 4 inches long, of a pale grey, -slightly mottled with fine streaks and dark spots. The fur on the flank -is longer, and white, with very pronounced markings of dark spots, and -this part of the skin is generally worked separately. Skins with a bluish -tone are more valuable than those with a sandy or reddish hue. The lynx -inhabits North America as far south as California. The best skins come -from Hudson Bay, and also Sweden. They are generally dyed black or brown, -similar to dyed fox. - -~Marmot.~--18 × 12 inches. A rodent found largely in the south of -Germany. The fur is yellowish-brown, rather harsh and brittle, and without -under-hair. Also found in North America, China, and the best skins come -from Russia. It is dyed brown in imitation of mink or sable, the stripes -usually being put on in the completed garment. - -~Marten, Baum.~--16 × 5 inches. Also called Pine Marten, and is found in -the woods and mountains of Russia, Norway, Germany and Switzerland. It -has a thick under-hair with strong top-hair, and ranges from a pale to a -dark bluish-brown. The best are from Norway, are very durable and of good -appearance, and a good substitute for the American sable. - -~Marten, Japanese.~--16 × 5 inches. It is of a woolly nature with rather -coarse top-hair, and quite yellow in color. It is dyed, but it is not an -attractive fur, lacking a silky, bright and fresh appearance. - -~Marten, Stone.~--Size and quality similar to the baum marten. The color -of the under-hair is stony white, and the top-hair is a very dark brown, -almost black. Skins of a pale bluish tone are used natural, while less -clear colored ones are dyed, usually in Russian sable shades. They are -found in Russia, Bosnia, Turkey, Greece, Germany, and France, the best -coming from Bosnia and France. - -~Mink.~--16 × 5 inches. Is of the amphibious class, and is found -throughout North America, as well as in Russia, China and Japan. The -under-hair is short, close and even, as is also the top-hair, which is -very strong. The best skins are very dark, and come from Nova Scotia. In -the central states the color is a good brown, but in the northwest and -southwest, the fur is coarse and pale. It is very durable and an economic -substitute for sable. The Russian species is dark, but poor and flat in -quality, and the Chinese and Japanese sorts are so pale that they are -always dyed. - -~Mole.~--3-1/2 × 2-1/2 inches. Is plentiful in the British Isles and -Europe, and is much in demand on account of its velvety fur of a pretty -bluish shade. Although the skins are comparatively cheap, the cost of -dressing is high on account of the considerable amount of labor involved. -The pelt is very light in weight, but does not resist well the friction -of wear. - -~Monkey, Black.~--18 × 10 inches. The species usually found on the west -coast of Africa, is the one of interest to the fur trade. The hair is very -long, very black and bright, with no under-hair, and the white pelt is -very noticeable by contrast. - -~Muskrat, Brown, Black, Russian.~--12 × 8 inches. A very prolific rodent -of the amphibious class, obtained in Canada and the United States. It has -a fairly thick and even brownish under-hair, and a rather strong, dark -top-hair of medium density. It is a durable and not too heavy fur. It -is used natural, but recently the plucked, sheared and dyed skins have -found a very extensive use as Hudson seal, an imitation of real seal. The -so-called black variety of muskrat is found in New Jersey and Delaware, -but only in comparatively small numbers. The Russian is also very small -and limited in numbers. It is of a pretty silvery-blue shade with even -under-hair, with very little silky top-hair, and silvery-white sides, -presenting altogether a marked effect. - -~Nutria.~--20 × 12 inches. Is a rodent about half the size of the beaver, -and when plucked, has only about half the depth of fur, which is not so -close. It is often dyed a seal color, but its woolly nature renders it -less effective than the dyed muskrat. The skins are obtained from northern -South America. - -~Opossum, American.~--18 × 10 inches. Is a marsupial, the only one of -its class found outside of Australia. The under-hair is of a very close -frizzy nature, and nearly white, with long bluish-grey top-hair mixed with -some black. It is found in central sections of the United States, and is -frequently dyed imitation skunk. - -~Opossum, Australian.~--16 × 8 inches. Is of a totally different nature -from the American. Although it has fur-hair and top-hair, the latter is -sparse and fine, so that the fur coat may be considered one of close even -under-hair. The color varies according to the district of origin, from -blue-grey to yellow with reddish tones. - -Those from near Sidney are a light clear blue, while those from Victoria -are a dark iron-grey, and stronger in the fur-hair. The most pleasing -shade of grey comes from Adelaide. The reddest are the cheapest. The -ring-tailed opossum, 7 × 4 inches, has a very short, close and dark grey -under-fur, some almost black, but the skins are not used extensively. -The Tasmanian opossum, grey and black, 20 × 10 inches, is of a similar -description, but larger, darker, and stronger in the under-hair. - -~Otter, River.~--The size varies considerably, as does also the length of -the fur, according to the origin. It is found in greatest numbers in the -coldest northern regions, and with the best under-hair, the top-hair being -unimportant, as it is plucked out. Most of the best river otters come -from Canada and the United States, and average 36 × 18 inches. The skins -from Germany and China are smaller and shorter furred. The colors of the -under-hair vary from very dark brown to almost yellow. Both the fur and -the leather are extremely strong, and many skins are dyed imitation seal -after plucking. - -~Otter, Sea.~--50 × 25 inches. Is one of the most beautiful of furs. -The under-hair is of a rich, dense, silky nature, with short and soft -top-hair, which is not plucked. The colors range from a pale grey-brown -to a rich black, and many skins have a sprinkling of white or silver-white -hairs. The blacker the under-hair, and the more regular the silver points, -the more valuable is the skin. - -~Pony, Russian.~--This is a comparatively cheap, but very serviceable -fur, and possesses some very desirable qualities. It has a thin leather, -but is also scantily haired. Young pelts have a design on them somewhat -similar to broadtail lambs, or moire astrachans, but this design is lost -to a considerable degree by dyeing the furs. The hair, which is very -glossy, is generally dyed black, although the natural pelts are also worn -extensively. - -~Rabbit.~--10 × 16 inches. The fur is thick and fine, but the pelt is very -weak. It is a native of central Europe, Asia, North and South America, -New Zealand and Australia. The color ranges from white to black. France, -Belgium and Australia are the greatest producers of rabbits suitable for -dyeing black, the so-called French seal, for which they are mostly used. -At the present time the dyeing of rabbits constitutes a considerable -percentage of the total fur-dyeing operations in this country. The most -varied shades are produced on rabbit, and it probably is the basis of -the greatest number of dyed imitations of better furs. In addition to the -French seal, or sealine, rabbit is dyed in imitation of beaver, mole, etc. - -~Raccoon.~--20 × 12 inches. Varies considerably in size, quality and color -of the fur, according to the part of North America in which it is found. -The under-hair is 1 - 1-1/2 inches deep, pale brown, with long top-hair -of a dark and silvery-grey mixture of a grizzly type, the best having a -bluish tone, and the cheapest a yellowish or reddish-brown. The best skins -come from the northern part of the United States. The skins have a wide -use natural, but are also dyed dark blue, or imitation skunk, the latter -being a very effective and attractive substitute, and extensively used. -Sometimes the skins are plucked, and if the under-hair is good, the effect -is similar to a beaver. - -~Sable, American and Canadian.~--17 × 5 inches. The skins are sold in the -trade as martens, but since many of the skins are of a very dark color, -and almost as silky as Russian sable, they have come to be known as sable. -The prevailing color is a medium brown, while many are quite yellow. These -pale skins have been dyed so well that they can cheaply substitute Russian -sable. The finest skins are from the Eskimo Bay and Hudson Bay districts, -the poorest from Alaska. - -~Sable, Russian.~--15 × 5 inches. Belongs to a species of marten similar -to the European and American, but much more silky in the texture of the -fur. The under-hair is close, fine and very soft, the top-hair is regular, -fine and flowing, and silky, ranging from 1-1/2 to 2-1/2 inches in depth. -In color they vary from a pale stony or yellowish shade to a rich, almost -black, dark brown, with a bluish tone. The leather is exceedingly close -and fine in texture, very light in weight, and very durable. The Yakutsk, -Okhotsk, and Kamchatka sorts are good, the last being the largest and -fullest-furred, but of less color density than the others. The most -valuable, are the darkest from Yakutsk in Siberia, particularly those -having silvery hairs evenly distributed over the skin, but these furs are -very rare. - -The Amur skins are paler, but often of a pretty, bluish tone, with many -interspersed silvery hairs. The fur is not so close or deep, but is very -effective nevertheless. The paler skins from all districts are now tipped, -the tips of the hair being stained dark, the fastest dyes being used, and -only an expert can detect them as differing from the natural shades. - -~Seal, Fur.~--The sizes range from 24 × 15 inches to 15 × 25 inches, -the width being the widest part of the skin after dressing. The most -useful skins are the pups 42 inches long, the quality being very good and -uniform. The largest skins, known as wigs, and ranging up to 8 feet in -length, are uneven and weak in the fur. The supply of the best sort is -chiefly from the northern Pacific, Pribilof Islands, Alaska, northwest -coast of America, Aleutian Islands, and Japan. Other kinds are taken from -the south Pacific regions. The dressing and dyeing of seal takes longer -than for any other fur, but when finished, it has a fine, rich effect, -and is very durable. - -~Seal, Hair.~--This is chiefly used for its oil and leather, and not for -its fur. It has coarse, rigid hair, and no under-hair. - -~Skunk, or "Black Marten."~--15 × 8 inches. The under-hair is full, and -fairly close, with glossy, flowing top-hair about 2-1/2 inches long. The -majority of the skins have two stripes of white hair extending the whole -length of the skin. These were formerly cut out, but more recently are -dyed the same color as the rest of the skin. They are widely found in -North and South America. The best are from Ohio and New York. The skunk -is naturally the blackest fur, is silky and very durable. - -~Squirrel.~--10 × 5 inches. This size refers to the Russian and Siberian -types, which are practically the only kind imported for fur, other species -having too poor a fur to be of great commercial interest. The back of the -Russian squirrel has an even, close fur, varying from a clear bluish-grey -to a reddish-brown, the bellies in the former being of a flat quality and -white, in the latter, yellowish. The backs are worked up separately from -the bellies. The pelts, though light in weight, are tough and durable. -The tails are dark and very small, and considerably used. - -~Tiger.~--The size varies, the largest measuring about 10 feet from the -nose to the root of the tail. It is found throughout India, Turkestan, -China, Mongolia, and the East Indies. Coats of the Bengal variety are -short and of a dark orange-brown with black stripes. Those from other -parts of India are similar-colored, but longer in hair, while those -from the north and China are not only large in size, but have very long -soft hair of a delicate orange-brown, with very white flanks, and marked -generally, with the blackest of stripes. - -~Wolf.~--50 × 25 inches. Is closely allied to the dog family, and very -widely distributed over the world. The best are the full-furred skins -of a very pale bluish-grey with fine, flowing black top-hair, from the -Hudson Bay district. Those from the United States and Asia are harsher and -browner. The Siberian is smaller than the North American, and the Russian -still smaller. A large number of prairie-dogs, or dog-wolves, is also used -for cheaper furs. - -~Wolverine.~--16 × 18 inches. Is a native of America, Siberia, Russia, and -Scandinavia, and is of the general nature of the bear. The under-hair is -full and thick, with strong, bright top-hair about 2-1/2 inches long. The -color is of two or three different shades of brown on one skin, the center -being dark, and presenting the general appearance of an oval saddle, -bordered with a rather pale shade of brown, and merging to a darker shade -towards the flanks. This peculiar character stamps it as a distinguished -fur. It is expensive, and quite valuable on account of its excellent -qualities. - -~Wombat, Koala or Australian Bear.~--20 × 12 inches. It has a light grey -or brown, close, thick under-hair 1/2 inch deep, and no top-hair, with a -rather thick, spongy pelt. It is cheap, and well suited for rough wear. - - - - -CHAPTER II - -STRUCTURE OF FUR - - -Fur is made up of two main components, the hair and the skin, and each of -these has a very complex structure. - -In the living animal the skin serves as a protective covering, and also -constitutes an organ of secretion and of feeling; consequently it is -of a highly complicated nature. The skin of all fur-bearing animals is -essentially the same in structure, although varying considerably as to -thickness and texture. It consists of two principal layers, which are -entirely different in structure and purpose, and correspondingly different -in both physical and chemical respects: the epidermis, epithelium or -cuticle, which is the outer layer, and the dermis or corium, which is the -true skin. (Fig. 1A). - -The epidermis is very thin as compared with the corium. Its outer layer -consists of a tissue of cells, somewhat analogous to the horny matter -of nails and hair. The inner surface, called the 'rete malpighi,' rests -on the true skin, and is a soft, mucous layer of cells. These cells are -spherical when first formed, but as they approach the surface become -flattened, and dry up, forming the horny outer layer of the epidermis, -which is constantly throwing off the dead scales, and which is constantly -being renewed from below. It is from this inner layer of the epidermis -that the hair, the sweat-glands, and the fat-glands are developed. - -The corium, or true skin, consists essentially of white, interlacing -fibres of the kind known as connective tissue. These fibres are themselves -made up of extremely fine smaller fibres, or fibrils, cemented together by -a substance of a somewhat different nature from the fibres, the coriin. -Towards the center of the skin, the texture of the interweaving fibres -is looser, becoming much more compact at the surface just beneath the -inner layer of the epidermis. This part of the corium is so exceedingly -close that the fibrils are scarcely recognizable. It is in this part that -the fat-glands are situated, while the hair-roots and sweat-glands pass -through it into the looser texture of the corium. The surface next to the -flesh is also closer in structure than the middle portions of the skin, -and has somewhat of a membranous character due to the fibres running -almost parallel to the surface of the skin. The skin is joined to the body -proper by a network of connective tissue, frequently full of fat-cells. -This layer, together with portions of the flesh which may adhere to it, -is removed by the process called 'fleshing,' and this side of the skin -is known as the flesh side. The corium also contains a small proportion -of yellow fibres, known as 'elastic fibres,' which differ physically and -chemically from the rest of the skin substance. - -During the course of the development of the embryo animal, a small group -of cells forms like a bulb on the inner side of the epidermis, above a -knot of very fine blood-vessels in the corium. This group of cells grows -downward into the true skin, and the hair-root which is formed within it, -surrounds the capillary blood-vessels, drawing nourishment from them, and -thus forming the papilla. (Fig. 1A). Smaller projections also form on the -bulb, and the fat-glands are gradually developed. The sweat-glands are -formed in a manner similar to the development of hair. - -The individual hair fibre is quite as complicated in structure as the -skin, and is made up of four distinct parts. (Fig. 1B).[2] - - [2] Descriptions and figures taken from "Mammal Fur Under the - Microscope," by Dr. L. A. Hausman, in _Natural History_, - Sept.-Oct., 1920. - -The medulla, or pith, is the innermost portion of the hair, and is -composed of many shrunken cells, often connected by a network which may -fill the medullary column partially or wholly. - -Surrounding the medulla is the cortex, which is made up of spindle-shaped -cells fused into a horny, almost homogeneous, transparent mass, and -forming a large proportion of the hair shaft. - -In the majority of the fur-bearing animals, there is distributed within -and among the cells of the cortex a pigment in the form of granules or -minute particles, arranged in the different hairs in fairly definite and -characteristic patterns. It is to these pigment granules that the color -of the hair is due primarily. In some cases the coloring matter of the -shaft is uniformly diffused and not granular. - -[Illustration: FIG. 1 - -_A._ STRUCTURE OF SKIN. - -_B._ STRUCTURE OF HAIR.] - -The outermost coat of the hair, or cuticle, is composed of thin, -colorless, transparent scales of varying forms and sizes, and arranged -in series like the shingles of a roof. It is on these scales that the -lustre or gloss of the hair depends. Since lustre is due to the unbroken -reflection of light from the surface of the hair, the smoother the -surface, the glossier it will appear. When the scales of the cuticle are -irregular and uneven, the surface of the hair will not be uniform and -smooth, and the light reflected from it will be broken and scattered, and -consequently the hair will not possess a high degree of lustre. As a rule, -the stiff, straight hairs have the most regular and uniform arrangement -of the scales of the cuticle, and hence are the smoothest and glossiest. - -Fur hairs are in general either circular or elliptical in cross-section, -those which are circular being straight or only slightly curved, while -those which are elliptical in cross-section are curly like the hair of -the various kinds of lambs. - -Most fur-bearing animals have two different kinds of hair on their bodies. -Nearest to the skin is a coat of short, thick, soft and fine hair, usually -of a woolly nature, and called the under-hair, under-wool, or fur-hair. -Overlying the fur-hair is a protective layer of hair, longer and coarser -than the under-hair, and usually straight, hard, smooth and glossy. This -is called the top-hair, over-hair, guard-hair or protective hair. In some -furs, the top-hair constitutes one of the chief elements of their beauty, -while in others, the top-hairs are removed, so as better to display the -attractive features of the under-hair. The roots of the top-hair are -generally deeper in the skin than those of the fur-hair, and in some -instances where the top-hair is removed, as in the seal, the roots are -destroyed by the action of chemicals applied to the skin side, the roots -of the fur-hair being wholly unaffected by this treatment. - -The fur-hair and the top-hair in the same animal have different -medullary and cuticular structures, and these characteristics may be -used to distinguish the two kinds of hair. Figs. 2A and B illustrate -these differences. In each case, the two large hairs on the left of the -illustration are the guard-hairs, showing respectively the cuticular -scales and the medulla. On the right are the two fur-hairs showing the -scales and the medulla. - -Although composed of many different kinds of tissues, and varying so -greatly in physical structure, both the skin and the hair belong to -the same class of chemical compounds, namely the proteins. These are -highly complex substances, forming the basis of all animal and vegetable -tissues. There are many different kinds of proteins, varying somewhat in -their constitutions, but all show, on analysis the following approximate -composition of chemical elements: - - Carbon 50-55% - Hydrogen 6.5-7.3% - Nitrogen 15-17.6% - Oxygen 19-24% - Sulphur 0.3-5% - -The principal kinds of proteins found in the various fur structures -are albumins, keratin, collagen, and mucines. Albumins, of which the -white of egg is the most familiar variety, occurs to some extent in the -corium as serum in the blood-vessels, and also as the liquid filling -the connective tissues, known as the lymph. They are soluble in cold -water, but when heated to about 70° C., they coagulate and are then -insoluble. Concentrated mineral acids and strong alcohol will also effect -coagulation. - -[Illustration: FIG. 2 - -_A._ HAIR OF EUROPEAN BEAVER. - -_a._ TOP-HAIR. _b._ UNDER-HAIR. - -_B._ HAIR OF SKUNK. - -_a._ TOP-HAIR. _b._ UNDER-HAIR.] - -Keratin is the chief substance of which all horny parts of the animal -body are composed, such as the hair, nails or hoofs. It is the principal -constituent of the hair, the epidermis, and the walls of the cells of -the inner layer of the epidermis, or the 'rete malpighi.' Keratin is -particularly rich in sulphur, and is quite insoluble in cold water. -Caustic alkalies attack keratin-containing parts. - -The collagens are the principal proteins of the skin, forming largely the -substance of the connective tissue fibres, and consequently the framework -of the skin. They are insoluble in cold water, dilute acids and salt -solutions, and are only very slowly attacked by dilute alkalies. Dilute -acids and alkalies cause collagen to swell; concentrated acids, vegetable -tanning materials, basic chrome or iron salts cause it to shrink. By -boiling with water, dilute acids or dilute alkalies, collagen is split up -into gelatin or glutin. - -The mucines of the skin, intercellular material or coriin, are soluble -in dilute acids, in dilute solutions of alkalies and of alkaline earths -such as lime, and in 10% salt solution, but insoluble in water, and in -salt solutions of greater or less concentration than 10%. On drying the -skin, the mucines cement the connective tissue fibres, causing the skin to -become stiff, horny and translucent. The mucines are also constituents of -the cells of the 'rete malpighi.' The solubility of the mucines in dilute -solutions of alkalies and of alkaline earths causes the epidermis to be -loosened from the corium, when the skins are treated with such solutions -for some time. - -When raw skins are boiled with water, the greater part goes into solution, -the residue consisting chiefly of the keratins of the hair and epidermis -cells. On cooling, the solution solidifies to a jelly of gelatine. It -combines with both acids and alkalies. A property of the skin which is -of importance in the tanning operation of fur-dressing, and a quality -which also characterizes gelatine, is the capacity to absorb liquids -and swell up, without changing chemically. Raw pelts swell up easily -in pure cold water, but much more easily in solutions of dilute acids -or dilute alkalies, only a little of the skin material being dissolved. -In stronger solutions, the skins swell up less, while more of the skin -substance dissolves, and by prolonged action of strong acids or alkalies, -an almost complete solution of the skin is obtained, without, however, -any of the material decomposing. With very strong alkalies or acids, -the skin substance is broken up into simpler compounds, such as various -amines and ammonia. The swelling action of acids or of alkalies increases -with the increase in concentration of the acid or alkali, but only up -to a certain point, after which further increase in the strength of the -acid or alkaline solution causes a reduction in the swelling, and even -produces shrinkage. In the presence of neutral salts, like common table -salt, sodium chloride, the swelling action of acids, is reduced, but the -action of alkalies remains practically unaffected. - -When treated with the various chemicals, fur hair acts in a manner quite -similar to wool. If it be remembered that certain classes of furs are -derived from animals of the sheep family, such furs as Persian lamb, -krimmer, etc., it becomes apparent why chemicals should affect furs in -nearly the same way as wool. The great majority of furs differ from those -of the sheep family, in possessing much greater resistance to the action -of chemicals. The range is a wide one however, and no exact criterion can -be adopted. As a general rule, the reactions are most marked with fur-hair -of a woolly nature, so this may be taken as a standard of reference. - -Acids have relatively little action on the hair, when applied in dilute -solutions. The scales of the cuticle or epithelium are somewhat opened, -the fibre becoming slightly roughened thereby. Even at high temperatures, -the hair is quite resistant to the action of dilute acids. Concentrated -acids destroy the hair with the liberation or formation of ammonia, -hydrogen sulphide, and various amino acids. When treated with dilute -acids, the hair, especially if it is of a very woolly nature, retains -considerable quantities of acid, this phenomenon being probably due to -the fixation of the acid by the basic groups in the hair. Nitric acid -produces a yellow coloration when applied in dilute solution for a short -time. Sulphurous acid, the acid formed by the burning of sulphur, has a -bleaching action on the hair. - -Alkalies attack the hair, even in dilute solutions, and by longer action -complete decomposition sets in, with formation of ammonia and amino-acids. -Ammonium carbonate, soap, and borax are practically harmless in their -effect on the hair. Sodium and potassium carbonates roughen the hair on -prolonged action, even in dilute solutions. Calcium hydroxide on continued -action removes sulphur from the hair, causing it to become brittle. - -Salts of alkalies and alkaline earths do not affect the hair at all. -Salts of the heavy metals on the other hand, are absorbed in appreciable -quantities. From a dilute solution of alum, aluminum hydroxide is absorbed -by the hair, the potassium sulphate remaining in solution. Similarly with -copper, iron, and chromium salts, the metal oxides are fixed by the fibre. - - - - -CHAPTER III - -FUR DRESSING - -INTRODUCTORY AND HISTORICAL - - -Fur dressing has a twofold purpose. First of all, the putrefactive -processes must be permanently stopped, so that the skin may be -preserved as such, or worked up as some fur garment, without danger of -decomposition. Having taken measures to assure the endurance or relative -permanency of the pelt, the prime consideration is, of course, the -appearance of the hair. The hair must be so treated that all its inherent -beauty is brought out to the fullest extent. It must be made clean and -soft, and all the natural gloss must be preserved, and if possible, -enhanced. The appearance of the leather is relatively unimportant, since -it is not seen after the furs are made into garments. There are, however, -certain qualities which it is essential for the leather to possess after -being dressed, and these are, softness, lightness of weight, elasticity or -stretch, and a certain firmness or 'feel.' In other words the important -considerations in fur dressing are the employment of means, and the -exercise of care to preserve or even improve those characteristics of the -pelt which make it valuable. - -The dressing of furs has many features in common with the manufacture -of leather, which is a kindred art. But whereas in fur dressing the -prime consideration is the appearance of the hair, and the leather is of -secondary importance, in the production of leather, the hair plays no part -at all, since it is entirely removed from the pelt. The fundamental points -of resemblance between leather manufacture and fur dressing are in those -processes and operations which are concerned with the preservation of the -leather, and rendering it in the proper condition for use. - -Both leather dressing and fur dressing have an origin which may be -regarded as identical, and which dates back to the haziest periods of -antiquity. In the course of satisfying his needs, primitive man killed -the animals about him, and thus obtained his food. The killed animal also -furnished a skin, which after undergoing certain manipulations and other -treatments, could serve as a protective covering, ornament, or defensive -weapon. Since the skin in its natural state was hardly fit for use because -of its easy tendency to putrefaction, it is evident that man had to find -some means of preventing this decay in a more or less permanent fashion, -and moreover had to treat the skin so that it would be suitable for use, -by rendering it soft and flexible. The discovery of means to accomplish -these purposes was probably one of the first great steps forward on the -path of progress and civilization. - -There are evidences of the use of animal skins in the earliest periods -of antiquity, in fact it is a usage which may be literally regarded as -"old as the hills." One of the earliest written records of the employment -of the skins of animals as garments, is in the Old Testament, where it -states, "Unto Adam and to his wife did the Lord God make coats of skins, -and clothed them." Numerous other biblical references indicate the use -of animal skins for various purposes, sometimes prepared as leather, -with the hair removed. Among the Egyptians tanning seems to have been -a common occupation. The particularly attractive skins, like those of -the leopard or panther, were especially prized, and were made up as furs -for ornamental wear, rugs and decorations. The less valuable skins were -unhaired and made into leather. Although the tanning or leather-producing -processes of the Egyptians are quite unknown, numerous figures engraved in -stone afford an indication to some of the manipulatory operations, such -as soaking the skins, fleshing, softening with stones, stretching over -a three-legged wooden "horse," etc. Many articles, made of leather, have -been found in the various Egyptian sarcophagi, and all are in a splendid -state of preservation, after forty centuries, thereby indicating a very -efficient method of dressing animal skins. Likewise, the presence in the -museums of various articles, leather and fur, of Assyrian, Phoenician -and Persian origin, tends to show that these peoples also possessed a -considerable degree of proficiency in tanning. Frequent references in the -Greek literature show that leopard and lion skins were worn as war cloaks, -and they undoubtedly were properly made. In the _Iliad_ is described an -operation for the preparation of skins for use as garments, and the method -seems to be a sort of chamois dressing. - -The first method of tanning skins was, in all probability, that of rubbing -into the skins various fatty materials found close at hand, such as parts -of the animal, fat, brains, milk, excrement, etc., such an operation -constituting the basis of what is now known as the chamois dressing. One -of the reasons for believing that it was the first process to be used by -primitive man, is the fact that certain undeveloped tribes and races of -the present day still dress skins by it. The American Indians, even to -this day prepare skins by rubbing in, on the flesh side, the brains of -the animals which furnished the skins. The Eskimos dress skins by rubbing -in animal fats or fish-oil, and subsequently softening and stretching -the skins with their teeth in place of, or for want of other implements. -Usually, however, variously shaped stones or bones of animals are used -to obtain the proper degree of softness and flexibility. It is true, too, -that some of the skins dressed in this primitive fashion can scarcely be -excelled by any dressed with more modern processes and tanning methods. - -The next step forward in the preparation of animal skins for use was -undoubtedly the utilization of substances found in the earth. Common -salt, sodium chloride, was the most universally used substance of mineral -origin, just as it is today. Our prehistoric ancestors eventually -discovered the preservative action of salt, and applied it to skins. -While it was effective, it was not sufficiently permanent, so another -mineral, also of very common and wide occurrence was used in combination -with the salt, and the result proved quite satisfactory. This second -common mineral was alum. The use of alum, which is the basis of numerous -tanning processes to this day, seems to have been quite a popular method -of ancient times. Artemidorus, a Greco-Roman writer, mentions the use -of alum by the Greeks, and the Romans are known to have prepared a soft, -flexible leather called aluta (alum leather), by using it. In view of the -fact that Egypt had extensive deposits of alum, it is believed that the -alum-salt process was employed also by the Egyptians in the preparation -of leather. However, the evidence on this point is not conclusive. - -One of the most important methods of producing leather, either as such -or on furs, was with the aid of certain vegetable extracts, known as the -tannins, from which the process of tanning gets its name. The discovery -of the value of these materials for converting the decaying raw skin -into a leather which could be preserved for an almost indefinite length -of time, and which was flexible and soft as desired, was of far-reaching -importance. For it is only in very recent times that these tannins have -been superseded in part by new tanning substances whose use is simpler -and more time-saving. Yet there are unmistakable indications that the -tannins were employed for tanning at a period which reaches back to the -dawn of history. Although it is scarcely probable that the people who -used these materials could have known of the existence or the nature -of the particular substances in the vegetable extracts which actually -effect the tanning action, experience taught them to employ these plants -which possessed the highest content of active ingredients, and which, -consequently, were most effective in use. Tychios, of Boetius, a Greek -supposed to have lived about 900 B.C. and mentioned in the _Iliad_, is -considered the oldest known tanner, and was regarded by Pliny, a Roman -writer, as the discoverer of tanning, and of the use of the various -vegetable tanning materials. At any rate, the Greeks used the leaves of -a so-called tanning-tree, which was probably the sumach. The Egyptians -worked with the acacia, while the Romans used as tanning materials the -barks of the pine, alder and pomegranate trees, also nut-galls, sumach and -acorns. The Romans were quick to employ methods used by the peoples whom -they conquered, and it is in this way that they learned the use of many -of the plants mentioned, for tanning purposes. - -Many other ancient peoples had various processes of tanning, the methods -probably differing in each country. Thus the Chinese, Syrians, and much -later, the Moors, were each known for proficiency in a certain class -of leather tanning. It has been said that in general, even up to modern -times, tanning with nut-galls was the characteristic method of the Orient; -with oak-tan, that of the Occident, while the use of alum is regarded as -the method peculiar to the Saracens. - -In prehistoric times and the early centuries of civilization, skins or -pelts were prepared for use by the individual, the work usually being -done by the housewife and daughters, while the masculine members of the -family were engaged in hunting the animals and obtaining the skins. At a -later period, when people had advanced to the point where they lived in -cities, the preparing or dressing of skins became centered in the hands -of a comparatively small number of people, and thus the work took on the -aspects of a trade. The workers in fur were at first the same people who -made leather out of the skin, for the two kinds of work were very closely -associated. During the period of the Roman supremacy, historical records -show that the furriers, who did all the work connected with furs, from -purchasing the raw skins, dressing them, making them into garments, to -selling the latter, were organized into associations together with the -leather workers. After the fall of the Roman empire, and throughout the -centuries known as the Dark Ages, all traces of the furriers seem to -have been lost, but in the beginning of the Renaissance period in the -fourteenth and fifteenth centuries, we again find records of the furriers, -who were now all members of the furriers' guilds, also in association -with the leather workers. As formerly, all the work connected with the -production of fur apparel from the raw furs, was done by the master -furrier and his apprentices. The methods and the implements used, were -essentially the same as in Roman times, and in fact, up to a very recent -period there was very little change in either. - -With the advent of the great industrial era at the beginning of the -nineteenth century, the guild system became ineffective, but the -furriers continued their work as heretofore. Up to about the middle of -the nineteenth century, the furrier continued to be the only factor of -any importance in the fur trade. There was no need for speed in his -work, for the demands of the trade were not so urgent. The fact that -the dressing of furs often occupied two to four weeks was no deterring -factor in his business. However, with the great expansion of the fur trade -about this time, it became impossible for the individual furrier to do -everything himself, and keep up with the requirements of his customers. -Specialization commenced, and establishments were set up solely for fur -dressing. The traditional time- and labor-consuming processes were still -used, but the efficiency of work on a large scale enabled the fur dressers -successfully to fill their orders. But the fur trade continued to grow by -leaps and bounds, and very soon the fur dressers were no longer able to -meet the demands of the trade. It was then that the science of chemistry -came to the aid of the fur dresser, and helped him meet the exigency. By -devising dressing processes which were cheap and efficient, and which only -required several hours, or at the most one or two days, as compared with -as many weeks, the chemist brought the fur dresser out of his dilemma. -And with the adoption of mechanical time- and labor-saving devices, the -fur dressing industry has made wonderful progress. - - - - -CHAPTER IV - -FUR DRESSING - -PRELIMINARY OPERATIONS - - -The fur dresser receives the skins in one of two shapes, flat or cased, -depending on the manner in which they were removed from the animal. Flat -skins, as for example, beaver, are obtained by cutting on the under side -of the animal from the root of the tail to the chin, and along the inner -side of the legs from the foot to the first cut. The skins are either -fastened to boards or attached to wooden hoops slightly larger than the -skins, so as to stretch them, and are then carefully dried, avoiding -direct sunshine or artificial heat, as it is very easy to overheat the -skins and thereby ruin them. The great majority of skins, however, are -cased. The pelts are cut on the under side of the tail, and along the -hind legs across the body, the skin being then removed by pulling it -over the head off the body like a glove, trimming carefully about the -ears and nose. The skin is thus obtained inside out, and is drawn over a -stretching board or wire stretcher of suitable shape and dimensions, so -as to allow the skin to dry without wrinkling. The pelts, after drying -in a dry, airy place, are removed from the stretchers and are ready for -the market. With some furs, as foxes, the skins are turned hair-side out -while still somewhat moist, and then put on the stretcher again till fully -dried. In most cases, however, skins are sold flesh-side out. Throughout -the various dressing operations cased skins are kept intact, being turned -flesh-side out or hair-side out according as the processes are directed -to the respective sides. The pelts are only cut open if they have to be -dyed, or after the manufacturer receives them, when they have to be worked -into manufactured garments. - -A distinction which is made by fur dressers and dyers, and also by the fur -trade in general, divides furs into those derived from domestic animals, -particularly the various kinds of sheep, including also the goat species, -and those obtained from other animals by trapping. In fact, at one time, -and to a certain extent even to-day, dressers were divided into two groups -based on this distinction, one class dealing only with furs obtained -from the sheep family, and the other working with other kinds of furs. -This differentiation is not a simple arbitrary one, but has a rational -justification. As mentioned before, the manner and habit of living of the -animal are important factors in determining the nature and constitution of -its skin, both leather and hair. The structure of the body being dependent -primarily upon the nature of the food absorbed by the animal, it is only -natural that herbivorous or vegetable-eating animals such as sheep and -goats, should possess fur of a different sort from that of the carnivorous -or meat-eating animals, such as the majority of fur-bearers are. It also -seems clear that furs differing in their character and constitution should -require somewhat different treatments, and accordingly the methods are -modified when furs like lambs or goats are dressed. To a great extent, -however, the fundamental operations are similar for all furs, regardless -of nature or origin, and these will be discussed briefly. - -Inasmuch as the first great purpose of fur dressing is to render the -skins more or less permanently immune from the processes of decay, it -is necessary to prepare the pelts so as to be most fit to receive the -preserving treatment. The skins as they are delivered to the fur dresser -have, in the majority of cases, been stretched and dried to preserve -them temporarily, while in some instances, especially with the larger -furs like bears and seals, they are salted and kept moist. The flesh-side -of the pelt still has considerable fleshy and fatty tissues adhering to -it, and the hair is generally soiled and occasionally blood-stained. In -order to get the pelts into such a condition that they can be worked -and manipulated, they first have to be made soft and flexible. Very -greasy skins are scraped raw in order to remove as much as possible of -the attached fat, the operation being known as beaming or scraping. The -typical beam, shown in Fig. 3, consists of a sloping table usually made -of some hard wood, and placed at an angle of about 45°. It is generally -flat, although in some instances convex beams are also used, about a yard -long, 8 to 10 inches wide, and firmly supported at the upper end. The skin -is placed on the beam, flesh-side up, and is scraped with a two-handled -knife (Fig. 4), always in a downward direction. - -[Illustration: FIG. 3. BEAM.] - -[Illustration: FIG. 4. KNIVES USED IN FUR DRESSING.] - -The first step in softening the skins is to get them thoroughly moistened, -and this is variously done, depending on the nature of the skin. Lambs, -for example, require the gentlest means of wetting them, while rabbits -can stand soaking in water for several days. The manner and duration -of moistening must be adjusted to the character of the pelt. For the -putrefactive processes which were stopped by stretching and drying the -skins, continue as soon as the pelt is again moistened. The progress -of decay causes the evolution of certain gases, the simplest of which -is ammonia, and eventually, if permitted to proceed, brings about the -complete disintegration of the skin tissue. It has been found that a -certain amount of gas formation is necessary to loosen up the fibres in -order to get the best quality of leather after tanning. This process must -be interrupted at the proper time and not allowed to proceed too far. - -Skins which have been preserved fresh by salting, require only a -comparatively short time (about 2 hours) to become softened by soaking -in clean, soft water. Most dried skins need a longer treatment before -they are sufficiently flexible. The addition of certain substances to the -water facilitates and accelerates the softening. In some instances salt -water is used for soaking the pelts, the preservative action of the salt -tending to prevent any loosening of the hair. A solution of 1/4% borax -is very effective in rendering the skins soft, and clean as well. Borax -has an exceedingly mild alkaline action, and causes a slight swelling of -the skin tissue, which then absorbs the water more readily. Being also -preservative and antiseptic, borax tends to prevent decomposition of the -skin tissue. Another chemical of a different nature, but equally effective -is formic acid, used in the proportion of 1.5-2.5 parts per 1000 parts of -water. Formic acid also induces a swelling of the skin, the pelts being -soaked in a short time, and the antiseptic action of the acid obviates the -possibility of the hair becoming loose. The water used should be fresh and -clean, and the soaking must be stopped as soon as the skins have become -soft and flexible. Sometimes the skins are allowed to soak overnight in -water, while in other cases, the pelts are just moistened by dipping in -water until thoroughly wet, and then laying them in a pile for several -hours, or overnight. Another method which is practised with certain types -of skins is the use of wet sawdust or of sawdust moistened with salt -water. The fur skins are either embedded in the sawdust or drummed with -it for several hours, or until sufficient moisture has been absorbed -to render them flexible. By this means there is no danger of the skins -being over-soaked, or of the hair being loosened. When the skins have -been properly wetted, they are drawn with the flesh-side across the edge -of a dull knife-blade, in order to help loosen the texture of the skin. -They are then put into a tramping machine and worked until completely -softened. In the case of large or heavy skins, the moistened pelts are -worked on the beam with a dull beaming knife to impart thorough softness -and flexibility. - -The pelts are then cleaned with particular reference to the hair. With -some furs this is accomplished simply by drumming for several hours with -dry sawdust, whereby the oil and dirt are removed from the hair, and the -hair is then freed from the sawdust by caging. Other skins are washed, -being passed through a weak soap solution for a short time, the dirty -spots being brushed. Occasionally an extract of soap-bark is used in -place of the soap, being even more effective. The cleansed skins are then -thoroughly rinsed to remove any of the cleaning material, which would -affect the gloss of the hair if allowed to remain on the skins. Then in -order to eliminate as much as possible of the water in the skins, they -are hydro-extracted, a centrifugal machine of the type shown in Fig. 5 -being used. The basis of its action depends on the utilization of the -principle of centrifugal force. The machine consists essentially of a -perforated metal basket generally made of copper, capable of being rotated -at a high speed. Surrounding the basket is an iron framework, polished or -enamelled on the inside. The wet skins are placed in the rotating basket, -fur side toward the perforations, and the water which is thrown off from -the skins passes through the little holes, and is caught up on the walls -of the outside frame, from where it is led off through suitable ducts. -The centrifugal device is properly equipped with balancing and regulating -attachments, as well as with a brake. The power may be applied by the -over-drive or the under-drive as is most desirable in the particular case. -The inner surface of the basket can also be enamelled or otherwise made -resistant to the action of acids or other chemicals. - -[Illustration: FIG. 5. CENTRIFUGAL MACHINE. - -(_Fletcher Works, Inc., Philadelphia_)] - -When the skin is removed from the animal, as much as possible of the -adhering fat and flesh is scraped off, but in spite of this, and in -spite of subsequent beaming by the fur dresser, there is always a thin -layer of flesh and fatty material remaining and this must be removed so -as to expose the corium, enabling the efficient action of the chemicals -used in the tanning processes. The process of removing this undesirable -layer from the flesh-side is known as fleshing. It is a rather delicate -operation, requiring considerable experience and dexterity on the part of -the worker, for it is exceedingly easy to cut into the skin and damage -the fur. A fleshing knife of the type commonly used is shown in Fig. 6. -It consists of a sharp blade fastened at a slight angle from the vertical, -with the cutting edge away from the workman, who straddles the bench, and -by drawing the skins back and forth across the edge of the blade, removes -all flesh and fat, leaving the corium free and clean. Large skins cannot -conveniently be fleshed in this fashion. They are placed on the beam, and -fleshed with a fleshing or skiving knife similar to the beaming knife, but -consisting of a slightly curved, sharp two-edged blade having handles at -both ends. Frequent attempts have been made to use suitable machines to -do this work. A type of machine which has met with considerable success -is depicted in Fig. 7. It is fashioned after the models used for the -fleshing of hides for leather manufacture, and has special adjustments -and regulating devices which afford protection for the hair part of the -fur. From time to time other fleshing machines are put on the market, yet -none of them seems to enjoy any great popularity, for fleshing is still -largely a manual operation. With some classes of pelts, fleshing presents -some difficulties, and chemical means have to be resorted to in order to -loosen the flesh sufficiently to enable proper fleshing. In the case of -large furs like bears, leopards, and the like, which while of no great -importance in the fur trade, are occasionally met by the fur dresser, -the skins after being soaked, and washed with soap-water, are partially -dried; then the flesh-side is treated with technical butter or oil, which -is tramped in. A mixture of salt water and bran is then applied to the -skins, thereby causing a swelling action to set in, and the flesh becomes -loosened, and is easily removed by fleshing on the beam. Seals receive a -special treatment which makes them soft, and gives them greater stretch -after they are tanned. A paste made by mixing a very dilute solution of -caustic soda with an inert substance like French chalk, china clay, etc., -is applied to the corium after the skins have been fleshed, then the -pelts are folded up, and allowed to lie for several hours. They are then -entered into a dilute solution of calcium chloride and left overnight. -After being washed in a paddle or drum, first with fresh water, and then -in water containing lactic or formic acid to remove the lime, the skins -are ready for tanning. - -[Illustration: FIG. 6. FLESHING KNIFE ON BENCH.] - -[Illustration: FIG. 7. FLESHING MACHINE. - -(_Turner Tanning Machinery Co., Peabody, Mass._)] - - - - -CHAPTER V - -FUR DRESSING - -TANNING METHODS - - -After the pelts have gone through the preliminary operations of softening, -washing and fleshing, they are ready to receive the treatment which -will convert the easily decomposing skin into leather of more or less -permanency, depending on the method used. - -During the past century, considerable study has been made both by -scientific and technical people, of the problem of leather formation. -Numerous theories as to the nature of the process have been evolved, but -even to this day, no satisfactory explanation has been given which would -account for all the facts as they are now known, so the matter is still a -subject of considerable controversy. Procter, who is one of the leading -authorities on leather today discusses the development of the tanning -theories as follows: - -"The cause of the horny nature of dried skin is that the gelatinous and -swollen fibres of which it is composed not merely stiffen on drying but -adhere to a homogeneous mass, as is evidenced by its translucence. If -in some way we can prevent the adhesion of the fibres while drying we -shall have made a step in the desired direction, and this will be the -more effective the more perfectly we have split the fibre-bundles into -their constituent fine fibrils, and removed the substance which cements -them. The separation of the fibres can be partially attained by purely -mechanical means.... Knapp, to whom we owe our first intelligible theories -of the tanning process, showed that by physical means the separation and -drying of the fibres could be so far effected as to produce without any -tanning agent a substance with all the outward characteristics of leather, -although on soaking it returned completely to the raw hide state. He -soaked the prepared pelt in absolute alcohol, which penetrated between, -and separated the fibres and at the same time dried them by its strong -affinity for water. More recently, Meunier has obtained a similar result -by the use of a concentrated solution of potassium carbonate which is even -more strongly dehydrating. - -"Knapp made a further step by adding to his alcohol a small quantity -of stearic acid which, as the alcohol evaporated, left a thin fatty -covering on the fibres which completely prevented their adhesion, and -reduced their tendency to absorb water; and he so produced a very soft and -white leather. Somewhat similar are the principles of the many primitive -methods which apply fatty and albuminous matters, grease, butter, milk, or -brains to the wet skin, and by mechanical kneading and stretching, aided -by capillarity, work these matters in between the fibres as the water -evaporates. Such methods are still used, and enter into many processes in -which other tanning agents are also employed. - -"Building upon these facts, Prof. Knapp advanced the theory that the -effect of all tanning processes was not to cause a change in the fibres -themselves, chemical or otherwise, but merely to isolate and coat them -with water-resisting materials which prevented their subsequent swelling -and adhesion. True as this theory undoubtedly is in many cases, it can -hardly be accepted as the whole truth, and it seems incontestable that -frequently the fibres themselves undergo actual chemical changes which -render them insoluble and nonadhesive. - -"Before Knapp's work, the prevalent theory, at least as regards vegetable -tannage, had been a chemical one, started by Sir Humphrey Davy. If a -solution of gelatine be mixed in proper proportion with one of tannin, -both unite to form a voluminous curdy precipitate; and, according to -Davy's ideas, this was amorphous leather. Against this, it was urged -that even the supposed 'tannate of gelatine' itself could not be a -true chemical compound, since the proportions of its constituents were -considerably varied by changes in the strength of the solutions, or by -washing the precipitate with hot water; and further, that in chemical -compounds, the form was changed, and no trace of the original constituents -appeared in the compound; while in leather apart from some change of color -and properties, the original fibrous structure remained unaltered. - -"This reasoning appears much less conclusive now than it did in Knapp's -day. Against the last objection guncotton may be quoted as an instance -of profound chemical change with no alteration in outside appearance; -and it is recognized that, especially among complex organic substances, -chemical reactions are rarely complete, but that stable positions are -reached, so-called 'equilibria,' in which the proportion of changed and -unchanged substance is dependent on concentration or other conditions; -and that therefore such a precipitate might well be a mixture of gelatine -with a true gelatine tannate from which further portions of tannin might -be dissociated by water. - -"With the clearing up of old difficulties, however, the conflict between -chemical and physical theories has, as is usually the case, merely -passed into a new phase. Years ago, it was shown by Linder and Picton and -others, that liquids could be obtained which were not really solutions -of ions or molecules, but merely suspensions like that of clay in water, -or butter-fat in milk; but so finely divided as to appear clear and -transparent, and pass through filters like true solutions. Later, by -means of the ultra-microscope their discrete particles have actually -been made visible, each of them consisting of many molecules of the -suspended substance. Nevertheless, these particles have many molecular -properties, possessing plus or minus electrical charges; behaving like -large ions under the influence of an electrical current; and mutually -precipitating and neutralizing each other when positive and negative -are brought together. Such solutions are called 'colloid,' and those of -gelatine and tannin are of the class, so that it is now often said that -the precipitation of gelatine by tannin, and the fixation of tannin by -gelatinous fibre are merely 'colloidal' and 'physical,' and not 'chemical' -phenomena. Admitting the facts, the question still arises whether the -distinction between chemical and physical is not here one without a -difference; and whether between the purely ionized dilute solution of a -salt and the coarsely granular clay suspension there is any point where a -definite line of demarcation can be drawn. The writer inclines to the view -that there is not; and that ionic and colloidal combinations are extreme -cases of the same laws, both physical, and both chemical." - -There are several methods which are used in tanning furs, each having -its peculiar characteristics and qualities, and possessing individual -advantages and disadvantages. In order to be able to judge the merits of -the various processes, it is necessary to have a criterion which can serve -as a basis of reference. Fahrion, a recognized authority and investigator -in this field, gives a definition of leather which is usually accepted -as a standard for comparison. He says: "Leather is animal skin, which on -soaking in water and subsequent drying does not become hard and tinny, but -remains soft and flexible; which does not decay in the presence of cold -water; and which does not yield any gelatine on boiling with water." While -the requirements set forth in this statement are essential for leather, -and a compliance with them would also be desirable for tanned furs, a -somewhat less rigorous standard of conditions to fulfil is satisfactory -for the general needs and purposes of furs. The chief qualities which -tanned furs must possess, with particular reference to the leather side of -the pelt, are retention of softness and flexibility after being moistened -by the furrier for manufacturing purposes, and subsequent drying; and -freedom from a tendency to decay during this operation and thereafter. If -the furs are to be dyed, the effect of the dyeing must also be considered, -and the tanning must be such as to enable the dyed furs to possess the -above qualities. - -The most important tanning processes employed for furs are the following: - - 1. Salt-acid tan, or pickle. - 2. Mineral tans. - 3. Chamois tan. - 4. Formaldehyde and similar tans. - 5. Combination tans. - 6. Vegetable tan. - - -1. SALT-ACID TAN, OR PICKLE - -This is one of the most extensively used methods for tanning furs, and is -also very cheap and easily applied. A typical formula for this tan is the -following: A solution of salt is prepared containing about 10% of common -salt, sodium chloride, and to this is added 1/2 - 3/4 ounce of sulphuric -acid for each gallon of tanning liquor. The proportions may be varied -within certain limits, but the figures here given are those which have -proven successful in practise. The solution should be made in a wooden -or earthenware container, free from any metal, as it would be attacked -by the acid. The liquor is then applied to the flesh-side of the fleshed -skins by means of a brush, making sure to touch all parts of the pelt. -They are then placed in a pile and allowed to remain thus until tanned, an -operation which occupies a time ranging from a few hours to two or three -days depending on the thickness of the skins. When the corium has lost its -translucence and has become of a milky-white color throughout the entire -thickness of the skin, as can be seen by viewing a cross-section, the skin -may be considered tanned. In some instances, where the hair of the fur can -stand immersion without injury, the skins are entered into the pickling -solution and allowed to remain for 12 to 24 hours, which is generally a -sufficient time to tan them in this manner. - -The acid of the pickle causes the skin to swell, the salt then penetrating -between the fibres of the corium, and at the same time reducing the -swelling of the skin. The acid also neutralizes the alkaline products -of decomposition which may form, while the salt acts as a deterrent to -the progress of the putrefactive processes. When the skin is dried after -tanning, and stretched and finished, a soft white leather is obtained -which is permanent as long as it is kept dry. It is the salt which causes -the fibres of the skin to be completely differentiated and thus prevents -their adhesion. - -It is interesting to note that other acids besides sulphuric can be -used for the pickle, organic as well as mineral, formic acid in 1/4% -solution being especially effective and giving excellent results, but -is more expensive than the mineral acid. A method, which in principle -is identical with the pickle, but carried out in an entirely different -manner, is the lactic acid fermentation process, or "Schrot-beize" as it -is called in German. The procedure is in general as follows: "The fleshed -skins are placed on tables, flesh-side up, and covered with a layer of -bruised barley grains, or a mixture of 3 parts of wheat bran and 2 parts -of rye flour. Then the head, tail and legs are turned inward, and the -skins rolled up in little cushions, hair-side out, and placed in a vat. -When this is filled with the skins a solution of common salt is poured -over them, and they are allowed to remain thus in a moderately cool place -for 24 hours. After this time, the skins are carefully unrolled, so as -not to remove any of the adhering solid materials, and turning the skins -hair-side inward, they are laid flat together in pairs and placed in an -empty vat. After another 24 hours they are again unpacked and replaced in -another vat, care being taken each time to keep all the solid particles -adhering to the flesh-side. This operation is continued and repeated until -the skins are properly tanned, which takes from 10 to 14 days, depending -on the weather and the temperature. The skins are then removed, rinsed -free of the tanning substances, pressed, dried and finished." A somewhat -modified form of this process is the so-called Russian tan, which is -usually done in the following manner: 5 parts of bruised barley grains -are mixed with ten parts of luke-warm water in a vat, which is then -covered up. A small quantity of brewers' yeast is also added to aid in the -fermentation. As soon as the mixture develops a slight heat, one part of -fresh whey is added, and the fleshed skins entered into the tanning liquor -in which they remain for about 12 hours. They are then tramped in the -mixture so as to effect greater penetration, and left until the tanning -process is complete. Whey is the milk fluid left after the casein and most -of the fat have been removed from the milk by coagulation, and consists -practically of a solution of all the milk-sugar or lactose, and the lactic -acid of the milk, together with a small percentage of mineral salts, and -a slight amount of fat. By fermentation, the milk-sugar is converted into -lactic acid, which helps to effect the tan by swelling the skin. - -The effectiveness of the fermentation processes depends to a considerable -degree on the action of certain bacteria and yeasts. Bacteria are -one-celled organisms belonging to the vegetable kingdom, and some are so -small as to be scarcely visible under a microscope, while some indeed -cannot be seen by any means, their existence being inferred from their -effects. As they vary in size, bacteria also vary in shape, some being -spherical, others in the form of long, thin rods, while still others are -of a spiral shape; another common form is the dumb-bell shaped bacterium. -Some types are provided with what are known as flagella, which resemble -fine hairs attached to the body of the organism, and which enable it to -move about actively in liquids. The food of bacteria is always in liquid -form, as only in this condition can it be absorbed. However, some kinds of -bacteria attack solid substances from which they obtain their nourishment, -but this is done in an indirect way, by secreting certain fluids known as -enzymes, which dissolve or digest the material and convert it into a form -that can easily be absorbed by the bacteria. The enzymes are non-living -chemical substances, which possess the peculiar property of bringing -about the chemical change of an almost indefinite amount of material -upon which they act, without themselves being in any way changed. Yeasts -also act in a manner similar to the bacteria in causing various chemical -changes, particularly inducing fementations. In the simple "Schrot-beize," -the starch contained in the bran or barley grains is first converted to -a soluble sugar by means of enzymes secreted by the bacteria which are -always present. This sugar then undergoes an acid fermentation, with -the formation of lactic and acetic acids, due in this case to organisms -known as the _bacterium furfuris A_ and _B_. The action of the Russian -tan is similar, but quicker. In this case, the sugar is already present -in soluble form, and the yeast cells cause its fermentation with the -production of lactic acid. In both cases, the acids as they form swell -and loosen up the skin fibres slowly, the salt penetrating between them, -and keeping them separated on drying. Both methods give results which -are equally good, but by the Russian tan the skins acquire a disagreeable -odor, which makes this method of dressing objectionable. - -The lactic acid fermentation processes have an advantage over the pickle, -in that the slow formation of weak organic acids with their gradual action -produce a softer leather, with a gentler 'feel,' the presence of the flour -and the grains of the tan, aside from their tanning action, contributing -to the fullness and softness of the leather. There is also less likelihood -of the leather being subsequently affected by the presence of the acid -in it, as lactic and acetic acids are much less injurious than sulphuric -acid to leather. These disadvantages of the pickle can to a large degree, -be overcome without any great difficulty. On the other hand, the matter -of the length of time of the tanning process, shows the acid pickle at -a great advantage, and so, especially for furs other than those obtained -from sheep and goats, the pickle is in most cases used as the principle -method of tanning. In Austria, Russia, and to a certain extent in Germany -also, the "Schrot-beize" is still considerably employed, chiefly for -dressing sheep and lamb skins. The dressing of the various kinds of -Persian lambs, caraculs, astrachans, etc., in the native center of the -industry in Buchara and surrounding districts, is also a "Schrot-beize," -barley, rice flour or rye flour, and salt water being used to prepare the -skins, the manipulations being essentially the same as those described -above, although carried out in cruder and more primitive fashion. - - -2. MINERAL TANS - -The basis of the tanning of furs by means of solutions of mineral -compounds is the fact that the basic salts of certain metals are capable -of producing leather. It has been found that compounds of aluminum such as -alum or aluminum sulphate, or any other soluble neutral salt of aluminum, -possess tanning powers. Other metals which are capable of forming salts -of the same type are also endowed with the quality of converting skin -to leather under suitable conditions, chromium and iron being the most -important metals in this connection. Chemically these metals all belong -to the same group, and have properties which are very similar in many -respects, the characteristic of most importance for tanning purposes -being the quality of forming soluble basic salts by the addition of -alkalies or alkaline carbonates to solutions of their neutral salts, or -in certain instances simply by the action of water upon these neutral -salts. By neutral salts are meant those in which the metallic content is -combined with the normal proportion of acid; while basic salts are those -in which the acidic portion is present in less than the normal ratio, -being partially replaced by a hydroxide group. When the acid part of -the salt has been entirely replaced in this way, the compound is called -a hydroxide or hydrate of the metal. Between the neutral salt and the -hydroxide several different basic salts are possible, some being soluble, -while others are insoluble. If into a solution containing a basic salt of -either aluminum, iron or chromium a skin be entered, a part of the basic -salt will be precipitated on it in insoluble form. Inasmuch as neutral -salts of these metals when dissolved in water split up to a small degree, -into free acid and soluble basic salt, a skin immersed in such a solution -will also absorb the basic salt in an insoluble form. Upon these facts in -general, depends the action of the mineral tans used in tanning furs. - - -A. _Alum Tan_ - -The alum tan is one of the oldest methods of producing leather, being -employed by the Romans about two thousand years ago, and it is believed, -by the Egyptians at a much earlier period. Its extensive use in Europe, -however, dates from the time of the conquest of Spain by the Moors, who -introduced the process. - -At the present time, rabbits and moles are tanned by this process, as are -also at times other furs such as muskrats, squirrels, sables, martens, -etc., when a better tan is desired than that produced by the pickle. -Ordinary alum, which is a double sulphate of aluminum and potassium, and -aluminum sulphate are the chief compounds used for this tan. In recent -years, the aluminum sulphate has to a considerable degree replaced the -alum for tanning, inasmuch as it can be cheaply obtained in a sufficiently -pure form, and contains about one and one-half times as much active -aluminum compound as does alum. - -While the aluminum salt can be used alone for tanning, it produces a -stiff, imperfect leather, so salt is always added. The ratio of the salt -to the aluminum sulphate or alum can vary within rather wide limits, the -mixtures used in practise ranging from one part of salt to four parts -of the aluminum compound, up to equal parts of both, or even in some -formulas, a greater proportion of salt than of the other constituent. -Ratios which are most common are four of alum to three of salt, or two of -alum to one of salt. - -When aluminum sulphate is dissolved in water, a small part of it splits -up into a soluble basic salt and an equivalent amount of free acid. The -reaction may be shown as follows: - - Al{2}(SO{4}){3} + 2H{2}O = Al{2}(SO{4}){2}(OH){2} + H{2}SO{4} - aluminum water basic aluminum sulphuric - sulphate sulphate acid - -When a skin is entered into such a solution, the free acid is absorbed, -causing a swelling of the pelt. While this is taking place, a further -quantity of the neutral aluminum salt splits up into more basic salt and -free acid. At the same time the basic aluminum sulphate is also taken -up by the skin, probably attaching itself to some of the acidic groups -contained in the skin substance, in a manner analogous to the combination -of the acid with the basic groups of the skin substance. A point is -reached, however, when the skin is no longer able to take up more of the -basic salt, for the presence of the acid undoubtedly acts as a deterrent. -The skin, if dried after such a treatment contains a small amount of -aluminum, which is insufficient to tan the pelt properly, and as a result -this comes out in an undesirable and quite useless condition. If to the -solution of the aluminum sulphate salt is added, a different result is -obtained. To a certain extent the salt acts here as in the pickle. The -skin on absorbing the free acid of the solution naturally swells, but the -salt reduces this swelling, and at the same time, by penetrating between -the fibres and dehydrating them, produces a leather as in the pickle. -In addition, the presence of the salt enables a greater amount of basic -aluminum sulphate to be formed, and thus a greater quantity is taken up -by the skin. On drying and stretching after such a treatment, a soft, -flexible and stretchable leather is obtained. - -The number of formulas for tanning furs by this process is legion, the -principle being the same in every instance, and mixtures of salt and alum -or aluminum sulphate form the basis of the various tans. Following are a -few typical formulas, which have been found to be of practical value: - -A solution is prepared by dissolving 7.5 lbs. of alum and 3 lbs. of -common salt in 20 gallons of water. When cool, the clean, fleshed skins -are entered, being paddled or drummed for a short time and then allowed -to remain until tanned. By this method the hair also takes up some of the -alum, and if the skins are to be dyed, unevenness may result. In order to -avoid this, the tanning may be effected by brushing a stronger solution -on the pelt. A mixture of 4 lbs. of alum and 3 lbs. of salt, dissolved -in 8 gallons of water, and made into a paste by the addition of 4 lbs. of -flour, is applied to the flesh-side of the skins. These are then placed in -pairs, flesh-side together, and allowed to remain in a pile until tanned. -Sometimes a second application is given. The flour may be omitted, but it -serves to cause the tanning mixture to adhere better to the skins. - -Still another method is the following: Into the flesh of the moist, -fleshed skins is rubbed a mixture of two parts of dry powdered alum with -one part of salt. After allowing time for it to be absorbed, another -application is given, rubbing in well, and especially treating the thick -parts. The pelts are then folded up, or rolled together, flesh-side in, -and placed in a vat or tub, which is covered up to prevent drying. They -are left so until tanned, as shown by examination and test. They are then -rinsed, hydro-extracted and dried, and after stretching and finishing, a -soft, white, pliable leather is obtained. - - -B. _Chrome Tan_ - -By using chrome alum instead of ordinary alum, together with salt, skins -can be tanned, but the leather formed is not altogether satisfactory. -The basic principle here is the same as in the alum tan, depending on the -formation of soluble basic chrome sulphates in the solution of a neutral -sulphate. The method employed at the present time, the so-called one-bath -process as distinct from the two-bath process, which cannot be applied -for tanning furs, involves the production of the basic chrome sulphate by -the addition of an alkali or an alkaline carbonate to the solution of the -neutral salt. It was Prof. Knapp who first published this process as early -as 1858; but it was not until 1893 that it was shown to be of practical -value, and was then patented in this country by Martin Dennis. Since that -time it has been in general use with but slight modifications. - -The chrome tan is used only to a limited extent in the tanning of furs, -the method requiring very careful treatment and accurate supervision -during the various stages of the process, and the leather coming out -colored a pale-blue-green tint, which for some purposes is objectionable. -In some plants ponies and rabbits are tanned with chrome; and when the -skins are to be dyed by means of certain coal tar dyes, they have to -receive a chrome tannage. The leather produced by a chrome tan is very -durable, and possesses great resistance to the action of water. - -Any salt of chromium, with either mineral or organic acids, can be used, -but chrome alum is the one most commonly employed. If a skin is entered -directly into a solution of a chrome salt made basic with an alkali, the -precipitation of the insoluble basic salt will take place very rapidly, -and the tanning will be only superficial. The procedure is therefore -first to treat the skins with a chrome solution which forms only small -quantities of the basic salt. After the skins are impregnated with the -solution, this is made basic, so that the real tan will take place within -the skin tissues among the fibres of the corium. A common formula is the -following: 5 lbs. of chrome alum are dissolved in 10 gallons of water. -The skins are entered into the solution at about 70° F. and paddled for -about 2 hours, or drummed for one hour. Then a solution of three pounds -of washing soda is added slowly to the liquor which is then stirred up -well, and the skins drummed or paddled again for an hour or two, and then -left in the liquor for 12 to 24 hours till completely tanned. The skins -are rinsed, and washed in 1/2% solution containing 2/3% of the weight -of the skins of borax. The pelts are then well washed in clean water, -hydro-extracted and dried. - - -C. _Iron Tan_ - -Tanning by means of iron salts has thus far been merely a matter of -scientific interest and has not found any practical use. The principle -involved is identical with that of the preceding mineral processes. - - -3. CHAMOIS TAN - -The chamois dressing, as previously noted, is undoubtedly the oldest -method of preparing leather from skin, the various fat-containing -substances derived from animals, fish, birds, etc., being used for the -purpose. The chief object of the fat was to coat the fibres of the skin, -thus preventing their adhesion, and at the same time rendering them -resistant to water. In the true chamois tan, the fat seems to have also -a chemical function in contradistinction to the other which is merely -physical or mechanical. For, if skins tanned by the chamois process -be treated with a weak solution of an alkali, all the fatty materials -should be removed thereby, but this happens only to a small extent, the -pelt retaining its softness and pliability, and the other characteristic -qualities of leather, indicating that the fat is combined intimately with -the skin substance in a permanent fashion. - -In tanning furs, various oils and fats are used, but not all are capable -of producing a chamois tan. Among the fatty materials are mineral oils, -and vegetable and animal oils and fats. Mineral oils are the distillation -products of petroleum, partially liquid, and partially solid. Being -inert substances, they have no tanning effect, but serve merely as -water-proofing or fattening materials. Except for their oily nature they -have nothing in common with fats, being quite unaffected by solutions of -alkalies or of acids. - -Vegetable and animal fats and oils are, when pure, neutral substances -formed by the combination of fatty acids with glycerine. They possess -the property of saponification, that is, of forming a soap when treated -with an alkali, the soap being the alkaline salt of the fatty acid. -Under certain conditions, the fat can be split up into free fatty acid -and glycerine by the action of acids, or even water alone. Some fats -on long standing, split up in this way spontaneously in the presence of -moist air. As a general rule, those fats which exhibit this property to a -marked degree are affected by contact with the air, due to the absorption -of oxygen which reacts chemically with the fats, forming what are known -as oxy-fatty acids, usually less soluble, and having a higher melting -point than the original fats. Vegetable and animal fatty materials are -classified on the basis of this phenomenon of absorbing oxygen from the -air, those possessing this quality to a great degree being called "drying -oils," others being "partially drying," or "non-drying." Olive oil, -castor oil, cocoanut oil and cottonseed oil are examples of non-drying -or partially-drying vegetable oils, linseed oil being the most important -drying-oil in this class. Tallow, lard, butter-fat, neats-foot oil are -non-drying animal fats, the drying oils being seal oil, whale oil, and -cod-liver oil. - -[Illustration: FIG. 8. TRAMPING MACHINE OR "KICKER." - -(_F. Blattner, Brooklyn, New York._)] - -For tanning purposes, this property of absorbing oxygen is important, -because only with drying oils can a true chamois tan be obtained, -non-drying oils acting like mineral oils only as water-proofing materials. -The details of the chamois process are not quite clear, there being -considerable difference of opinion on the matter. But all the studies -on the subject tend to prove that there are at least two phases to the -process: first, the mechanical covering of the fibres with the fat, this -property being common to all fats or oils which may be used; and second, -the combination of the fat with the skin in some chemical way, as a result -of the oxidation of the fat, a characteristic found only in the drying -oils. During the oxidation of the fats, the glycerine in them is converted -to acrolein or acryl-aldehyde, which also aids the tanning. It was at one -time supposed that the tanning action was due to this aldehyde alone, -but a chamois tan can be made with fatty substances from which all the -glycerine has been removed. The evidence on this question, however, is -not quite conclusive. - -In general, the procedure of the chamois tan is as follows: The -hydro-extracted, fleshed skins are rubbed on the flesh-side with a good -quality of seal-oil. They are then folded up, and put into a 'kicker,' -where they are tramped for two or three hours to work in the oil. The -kicker is a machine such as shown in Fig. 8 consisting of a receptacle for -the skins, and two wooden hammers which work up and down mechanically, -turning and pounding the skins. (As many as 1000-1500 skins of the size -of musk-rats can be worked at one time in such a machine.) The pelts are -then taken out and hung up in a warm room for several hours, considerable -oxidation taking place. Another coat of oil is then applied, which is -again tramped in, and the skins are hung up once more and exposed to the -air to cause the oil to oxidize. After the skins are sufficiently tanned -they are rinsed in a weak soda solution to remove the excess oil, washed -and dried. When skins with fine hair such as marten, sable, mink, etc., -receive a chamois tan, they are not tramped in kickers as the delicate -top-hair will be broken, and the value of the skin thereby reduced. -Instead they are placed in small drums, together with metal balls of -varying sizes and weights depending on the particular fur treated, and the -oil is worked in by rotating the drum. Such a ball-drum, as it is called, -is shown in Fig. 9. - -[Illustration: FIG. 9. BALL DRUM. - -(_F. Blattner, Brooklyn, New York._)] - -In conjunction with the chamois tan may be discussed the process of -oiling, inasmuch as the method of application and the effect are both -similar to the chamois tan up to a certain point. It is customary to -treat skins tanned by any other method but the chamois process, with -some oil in order to render them more impervious to water. The greatest -variety of oils and fats can be used, the action in most cases being -simply the mechanical isolation of the skin fibres by such a substance, -thus corresponding to the first or physical phase of the chamois tan. -The chemical phase, if it takes place at all, is usually slight, and -is merely incidental. Oiling is generally applied either before drying -after tanning, or after drying, the oiled skins being placed in a kicker -and tramped to cause the oil to penetrate. In some instances the oiling -material is put in the same mixture as the tanning chemicals, and the -tanning and oiling are effected simultaneously. - -Among fatty substances used for oiling are mineral oils, such as paraffine -oil, and vaseline; animal fats, like train oils, butter, egg-yolk, -glycerine, neats-foot oil; vegetable oils, like olive oil, castor oil, -cottonseed oil; also sulphonated castor oil and sulphonated neats-foot -oil. These may be used singly or in various mixtures, an emulsion of an -oil and a soft soap also being frequently employed. - - -4. FORMALDEHYDE TANS - -Formaldehyde has proven to be of great value in the tanning of furs, -usually in conjunction with other processes. Formaldehyde is a gas with -a strong, irritating odor, and its 40% solution, which is the customary -commercial form, also possesses this quality. When skins are treated for -several hours with a very dilute solution of the commercial product, a -leather is obtained which combines the properties of the alum tan and -the chamois tan. Moreover, in the majority of observed cases, where furs -have been tanned with formaldehyde, the skins seem to acquire a certain -immunity to the attacks of vermin and moths. Although the skins do -not in any way retain the odor of the formaldehyde, nevertheless these -destructive agents seem to be repelled. - -Numerous processes have been devised which use formaldehyde in connection -with other substances for tanning. Thus in a German patent is described -a method involving the alternate or simultaneous treatment of pelts -with solutions of formaldehyde and alpha or beta naphthol. Both the -formaldehyde and the naphthol exercise tanning actions, but the process -is not used in practise. - -In 1911, Stiasny, a well-known leather chemist produced a synthetic -substance by the condensation of formaldehyde with a sulphonated phenol, -forming an artificial tannin. This chemical, called "Neradol D," exhibits -many of the properties characteristic of true tannins, although in no way -related by structure and composition. By the use of "Neradol D" a soft, -white and flexible leather is obtained, and it is therefore a suitable -tanning material for furs. - - -5. COMBINATION TANS - -In many instances more than one method is employed in tanning the furs, -and in this way what is known as a combination tan is produced. While the -various individual processes described give more or less satisfactory -results by themselves, they generally possess some features, which -for certain purposes may be undesirable, and which can be eliminated -or considerably reduced by using other processes at the same time or -subsequently. Some of the combination methods are, pickle with chrome -tan, alum tan with chrome tan, and formaldehyde tan with pickle, mineral -tan or chamois tan. By means of such combinations various qualities of -tanned furs can be obtained, and if it is desired to produce a pelt having -certain special characteristics, this can be brought about by combining -two or more standard methods. - -Some illustrations of combined tannages are the following: Alum-chrome -tan. The skins are tanned by the regular alum process, then the -constituents of the chrome tan are dissolved directly in the same bath, -and the chrome tan is effected as usual. Chrome-formaldehyde tan. To the -regular chrome tan solution is added 1/2 lb. of formaldehyde for every 10 -gallons of chrome liquor. The rest of the process is as ordinarily. - - -6. VEGETABLE TANS - -In practise, the vegetable tanning matters are not used for furs, although -in some special instances gambier cutch may be employed occasionally -with some other tan. However, many of these tannins also have dyeing -properties, and are used in dyeing the furs. In this connection it must -be mentioned that furs dyed with these materials also receive a vegetable -tan, which improves the quality of the leather to a considerable extent. - - -Comparison of The Various Tanning Methods - -In choosing a method for tanning any particular kind of fur, several -factors must be considered. The nature of the pelt, insofar as it is weak -or strong; the time, labor and cost of materials required by the tanning -process; the effect on the leather of the different dyes and chemicals -used in dyeing, if the skin is to be dyed, are a few of the points -requiring attention and consideration. - -For furs which are only to be dressed, a simple tan like the pickle will -suffice in most cases. Special instances, such as the rabbit and mole -already mentioned, and a few other furs are tanned by the alum method. The -pickle is undoubtedly the cheapest and simplest method of tanning skins, -and yields a soft, white leather which is permanent as long as it is kept -dry. If it is put into water, about 25% of the salt contained within -the pelt dissolves out, and the acid present swells up the tissues. If -the skin is dried in this condition, it will come out hard and brittle, -tending to crack very easily. By treating the leather before drying with a -strong salt solution, a good deal of the extracted salt will be replaced, -and on drying and stretching, it will work out soft. Skins tanned by -the "Schrot-beize" are affected by water in quite the same manner as the -pickled skins. - -The alum tan gives a leather similar to that produced by the pickle, but -with the advantage that the skins possess greater stretch and flexibility. -In its resistance to water, the alum-tanned pelt is quite as susceptible -as the other. As a general rule, the skin absorbs about 6% of its weight -of alum from the tanning solution, but gives up three-quarters of this -when it is soaked in water, producing on drying, a hard, stiff leather. -The chrome tan is especially impervious to water, easily resisting -temperatures of 80° C., and even boiling water. It is employed to only -a limited extent on account of the special effort and care required -to obtain satisfactory results, also because the pelt acquires a pale -blue-green color which is not desired on dressed skins. The chamois -tan, and some of the combinations of the formaldehyde tan with the other -methods, give very soft, flexible leathers which possess a sufficiently -great resistance to the effects of water and heat. - -In tests made to determine the best working temperatures for dyeing -skins dressed by the salt-acid tan, and for skins dressed by the chamois -process, some very interesting facts were brought out. These two tans -were chosen because they represent opposite extremes, the salt-acid tan -usually giving the poorest results, and the chamois tan giving the best -results in practise in dyeing. Other methods, except the chrome, range -between these two. The procedure in these experiments was to treat the -skins at ordinary temperatures in water, or dilute solutions of the -various chemicals and dyes usually employed in dyeing, and then heat these -solutions until the leather just began to shrink and shrivel up. This -point, called the shrinking point (S.P.), gave the temperature to which -the skins could be subjected in the given solution without danger to the -pelt. (The experiments and observations were made by Erich Schlottauer, -while director of a large German fur dressing and dyeing plant). - -The first observation made was that different furs tanned by the same -process were affected differently in the same solutions. Thus in plain -water, three furs, all tanned by the acid-salt tan, had shrinking points -varying by several degrees; similarly with two different furs tanned by -the chamois process, there was a variation in the shrinking point of two -degrees. The explanation of this discrepancy among the different skins may -be that there was a slight difference in the conditions under which they -were tanned, experiments showing that a maximum difference of 4° C. may -exist among skins tanned by the same process, but not under the same or -identical circumstances. Another reason for the variation may be the fact, -that some skins are more greasy than others, and are thus more resistant -to the effects of water or of some chemicals. The furs with the higher -shrinking points in water were those which naturally are more greasy than -the others. - -Weak solutions of acids tend slightly to lower the shrinking point, while -weak solutions of alkalies appreciably raise it, in both chamois-tanned -and salt-acid-tanned skins. Solutions of dyes and mordants as a general -rule increase the resistance of the skin to heat, varying quantities of -these substances having no, or little different effects on the shrinking -points. Previous treatment of the leather with some oil considerably -raises the shrinking point of the pelt. Formaldehyde effects a great -increase of the resistance of the skins to heat, especially with -chamois-tanned furs. The experiments in this case were made by first -treating the skins in the weak formaldehyde solution, and then determining -the shrinking point in plain water. - -Two skins, both dressed by the "Schrot-beize," a Persian lamb and an -astrachan, after dyeing had shrinking points almost 10 degrees higher than -when undyed. The extra tannage which the skins received from the tannins -used in the dye mixtures for these furs, accounts for this increased -resistance to heat. - -The following tables give the observed figures in the different -experiments: - - TABLE I - +-------------------+------+------+------+ - | | A | B | C | - | | S.P. | S.P. | S.P. | - +-------------------+------+------+------+ - |_Salt-acid Tan_ | C. | C. | C. | - |Australian Opossum | 46° | 58° | 45° | - |Marmot | 45° | 50° | 42° | - |Skunk | 47° | 56° | 43° | - | | | | | - |_Chamois Tan_ | | | | - |Mink | 52° | 61° | 45° | - |Muskrat | 50° | 58° | 42° | - +-------------------+------+------+------+ - A--Water - B--Water plus 1% Ammonia (s.g. 0.910) - C--Water plus 1% Sulphuric acid (66° - Beaumé) - - TABLE II - +-------------------+------+------+------+ - | | A | B | C | - | | S.P. | S.P. | S.P. | - +-------------------+------+------+------+ - |_Salt-acid Tan_ | C. | C. | C. | - |Australian Opossum | 53° | 52° | 54° | - | | | | | - |_Chamois Tan_ | | | | - |Mink | 59° | 59° | 59° | - +-------------------+------+------+------+ - A--1000 c.c. water plus 40 c.c. - Peroxide plus 5 c.c. ammonia - B--500 c.c. water plus 2 grams Ursol D - (Para-phenylene-diamine) - C--500 c.c. water plus 5 grams Ursol D - - TABLE III - +-------------------+------+------+------+------+ - | | A | B | C | D | - | | S.P. | S.P. | S.P. | S.P. | - +-------------------+------+------+------+------+ - |_Salt-acid Tan_ | C. | C. | C. | C. | - |Australian Opossum | 51° | 51° | 53° | 56° | - | | | | | | - |_Chamois_ | | | | | - |Mink | 59° | 59° | 61° | 62° | - +-------------------+------+------+------+------+ - A--500 c.c. water plus 5 grams ground - nut-galls - B--300 c.c. water plus 2 grams pyrogallic - acid - C--500 c.c. water plus 2 grams potassium - bichromate - D--Water, after treating leather with - rapeseed oil - - TABLE IV - +-------------------+------+------+------+------+ - | | A | B | C | D | - | | S.P. | S.P. | S.P. | S.P. | - +-------------------+------+------+------+------+ - |_Salt-acid Tan_ | C. | C. | C. | C. | - |Australian Opossum | 49° | 49° | 55° | 50° | - | | | | | | - |_Chamois Tan_ | | | | | - |Mink | 59° | 67° | 69° | 70° | - +-------------------+------+------+------+------+ - A--500 c.c. water plus 5 c.c. formaldehyde - for 1 hour - B--500 c.c. water plus 5 c.c. formaldehyde - for 12 hours - C--500 c.c. water plus 10 c.c. formaldehyde - for 3 hours - D--As in C, but treated with 500 c.c. water - plus 5 c.c. ammonia, instead of water - alone. - - TABLE V - +-------------+------+------+ - | | A | B | - | | S.P. | S.P. | - +-------------+------+------+ - | | C. | C. | - |Persian Lamb | 44° | 54° | - |Astrachan | 47° | 55° | - +-------------+------+------+ - A--Before dyeing - B--After dyeing - -As a result of these experiments it may be concluded that the maximum -temperature for drying salt-acid tanned skins should be 40° C., while -for chamois tanned skins the temperature may be permitted to reach 45° C. -without any danger of the leather being affected. Moreover, in the case -of pickled skins, the matter of extraction of the tanning agent, as well -as that of the leather becoming "burned" may be effectively counteracted -by brushing some oil or fat on to the leather side before dyeing the pelt. - -The shrinking points of skins dressed by the various tanning methods are -constant within certain limits, depending on the nature of the skin and on -the conditions of tanning, and it is possible by observing the shrinking -point, in conjunction with other characteristics of a given pelt, to -determine what method of tanning was used. - - - - -CHAPTER VI - -FUR DRESSING - -DRYING AND FINISHING - - -One of the most important operations of all the fur dressing processes is -the drying of the skins. For even when all the previous steps have been -successfully completed, there is still a great possibility of the skin -being injured if the drying is not properly and carefully carried out. - -The essential requirements for good drying are proper temperature, -uniformity and rapidity. The leather part of the fur cannot, in the -moist state, resist temperatures exceeding about 45° centigrade, for when -dried, the skin turns out hard and stiff, and cracks easily. The furs must -therefore be dried at an initial temperature of 25° to 30° centigrade, and -as the moisture is gradually removed, the temperature may be raised, for -the less water that remains in the pelt, the less is the leather affected -by the heat, and the more difficult is the removal of its aqueous content. - -If the drying process is not a uniform one, that is, if all the skins -in a lot are not subjected to the same drying conditions, then after the -drying has proceeded for a certain time, some skins may be quite dry while -others are not, or there may be as many different degrees of dryness as -there are skins drying. There is also the possibility of great variation -in the amount of moisture removed from different parts of the same skin. -Such a state of affairs requires an extra expenditure of time, labor -and heat power in order to get the whole lot of furs into a more or less -uniform condition. Moreover in some kinds of furs, especially those with -thick skins, when the drying is not even, there is danger of the epidermal -layer drying away from the corium, and subsequently peeling and cracking. -Uniformity of drying requires the maintenance of a reasonably constant -temperature equally distributed throughout all parts of the space where -the drying is done, so that all the furs may be dried under the same -conditions. - -Rapidity of drying is desirable not only because it is beneficial to -the condition of the pelt, but also from the point of view of practical -business economy. The space occupied by the drying should be as small -as possible compatible with the volume of work, and with the efficiency -of operation. Slow drying involves the use of much space to take care of -all the skins to be dried, or an accumulation of pelts ready to be dried, -neither of which conditions is efficient or desirable. - -It was formerly the general custom, still practised in some -establishments, to dry the skins by hanging them up, leather-side out on -lines in a large room or loft, the heat being usually supplied by steam -pipes. Such a procedure occupied often as long as two or three days to -get complete drying, involved a great deal of labor, and the results were -far from uniform. In fact, in order to get the skins more nearly equable, -it was necessary to subject them to an additional operation. This usually -consisted of rotating the skins in a closed drum for several hours, the -constant intermingling of the pelts in contact with each other causing -any moisture left in them to be evenly distributed throughout the whole -lot. The skins, by this process also are rendered somewhat softer and more -flexible, but by drying under proper conditions the entire extra operation -can be dispensed with, the furs coming out quite as soft and flexible -without the drumming. - -A great improvement was the adoption of large fans to circulate the heated -air in the loft, thereby approaching more nearly an even temperature. -More modern devices have, however, been developed, whereby drying can be -effected in the most uniform manner, with perfect control of temperature, -and requiring the least possible consumption of space, time, labor and -power. A typical arrangement consists of a large closed chamber, generally -constructed of steel, and divided into several compartments each of which -may be operated independently of the others. Air, heated over suitably -located steam pipes to the required temperature, is forced through the -various compartments by means of fans operated by power. The conditions -may be varied in each compartment, as to temperature or humidity, both -of which can easily be regulated, or all the compartments may be used -together as one unit. The skins are hung up on rods or lines in the -compartments, or on special frames for the purpose, which are then entered -into the compartments and the doors shut. The dry, heated air is forced -to pass over the skins, and takes up their moisture. At the further end -of the drying chamber is another fan which removes the moisture-laden air -after it has done its work. The drying is effected in from 6 to 24 hours, -and all skins are obtained in the same condition, for the process is quite -uniform and regular. - -Within recent years there has been evolved a highly efficient and -economical drying equipment, based on a somewhat different principle -than underlies any of the foregoing methods. The conveyor type of dryer, -as it is called, is admirably suited to the needs of the fur dressing -and dyeing industry, and is undoubtedly superior to any of the previous -systems of drying furs, in that it affords an enormous saving of space, -time, labor and power, and gives greater uniformity and presents better -working conditions. - -[Illustration: FIG. 10. DIAGRAMMATIC VIEWS OF CONVEYOR DRYER. _a._ SIDE -VIEW; _b._ END VIEW. - -(_Proctor & Schwartz, Inc., Philadelphia._)] - -The conveyor dryer consists essentially of a steel enclosure, through -which the skins pass on horizontal conveyors. Where special insulation -is necessary, asbestos panels are used to line the enclosure, making the -dryer absolutely fireproof, and enabling the maximum utilization of heat. -In the middle of the dryer are located the steam coils which furnish -the heat, and in many instances exhaust steam can be used as the source -of heat. Figure 10 shows diagrammatically the arrangement and operation -of the conveyor type of dryer. The enclosure is divided into several -compartments, in each of which a different condition of temperature and -humidity is maintained, the temperature being closely and accurately -regulated by an automatic control, and once the dryer has been set for -any condition, all skins will be dried exactly the same, regardless of -weather or season. - -[Illustration: FIG. 11. CONVEYOR DRYER. - -(_Proctor & Schwartz, Inc., Philadelphia._)] - -The skins to be dried are placed on poles which in turn are set on -the horizontal conveyors as in Fig. 11. As the skins pass through the -compartments, large volumes of air, heated to the required temperature -over the steam coils, are circulated among the skins by means of the fans. -Exhaust fans, properly placed, remove a certain quantity of moisture-laden -air when it has accomplished its full measure of work. When the skins on -the conveyors have passed the full length of the dryer, they are entirely -dry, and are then removed from the poles. (Fig. 12). The time required -for drying varies according to the nature of the fur from 1-2 hours to 6-8 -hours. In tests made to determine the relative efficiency of the conveyor -type of dryer as against the old "loft" method, it was found that there -was a saving of over 50% in power, and of 85% in floor space, as well as -a great saving of labor, when the conveyor system was used, the number -of skins dried in a given period of time being the same in both cases. -The advantages of the new method are easily apparent, and the saving -is sufficiently great with large lots of furs, to make an appreciable -difference in the final cost of dressing. - -If the skins have been dried by a modern drying system they all come out -in a uniform condition, and are ready to go on immediately to the next -operation. If, however, a form of the "loft" method of drying has been -used, it is customary to subject the skins to an additional process. The -dried pelts are put in drums with damp sawdust, and drummed for a short -time in order to get them into the proper condition. The drumming is -essential for the purpose of equalizing the condition of the pelts, some -being drier than others, and as a consequence of the contact with the -moist sawdust, they are all brought to the same degree of dryness. As a -result of this operation also, the skins become considerably softened. - -[Illustration: FIG. 12. DELIVERY END OF CONVEYOR DRYER. - -(_Proctor & Schwartz, Inc., Philadelphia._)] - -Then if the pelts have not been previously oiled during the tanning -process, or prior to the drying, they receive this treatment now. The oil -or fat is applied to the leather side of the furs, which are then placed -in the tramping machine for a short time in order to cause the oil to be -forced into the skin. The fibres of the corium thus become coated with a -thin layer of fatty material, which contributes greatly to the softness -and flexibility of the pelt, and increases its resistance to the action of -water, and also, in certain instances a partial chamois tan is produced, -thereby improving the quality of the leather. - -[Illustration: FIG. 13. STRETCHING MACHINE FOR CASED SKINS. - -(_Reliable Machine Works, Evergreen, L. I._)] - -The skins are now returned to the work bench, and subjected to the -stretching or "staking" process. This consists in drawing the skin in all -directions over the edge of a dull blade, which is usually fixed upright -in a post with the edge up. Or, the stretching may be done on the fleshing -bench, substituting a dull blade for the fleshing knife. Recently staking -machines are being used in the larger establishments, the work being -done much more quickly and efficiently. As a result of this operation, -the leather becomes very soft and flexible, every bit of hardness and -stiffness being eliminated, and the skins receive their maximum stretch, -thereby giving the greatest possible surface to the pelage. This not only -helps to bring out the beauty of the hair, but is also a decided advantage -from the economic point of view, as a considerable saving of material -is effected in this way, sometimes even to the extent of twenty-five per -cent. Cased skins are stretched in a somewhat different manner, by means -of stretching irons. These consist of two long iron rods joined by a pivot -at one end. The skins are slipped on to the irons, which are then spread -apart, and in this way the skins are stretched and softened. A machine -which does this work very efficiently is shown in Fig. 13. The skin is -drawn onto the stretching arms, in this case made of bronze, which are -then forced apart by pressing on a pedal. When properly stretched to the -maximum width in all directions possible, and thus thoroughly softened, -the skin can easily be reversed, that is, turned hair-side out. As many as -6000 skins can be stretched, or 4000 to 5000 skins stretched and reversed -by one man in one day on such a machine. - -[Illustration: FIG. 14. FUR BEATING MACHINE. - -(_S. M. Jacoby Co., New York._)] - -The pelts are then combed and beaten. In smaller plants these operations -are done by hand, but suitable machines are being employed. In order to -straighten out the hair, it is combed or brushed. Then in order to loosen -up the hair, and to cause it to display its fullness, the furs are beaten. -This process is also done by hand in some establishments, but up-to-date -places use mechanical devices for this purpose. A type of machine which -has proven very successful, and is enjoying considerable popularity -is shown in Fig. 14. These machines are also made with special suction -attachments which remove all dust as it comes out of the beaten skin, -thereby making this formerly unhealthful operation thoroughly sanitary -and hygienic. - -The final process is drum-cleaning. This operation is intended -specifically for the benefit of the hair part of the fur, and is very -important inasmuch as the attractive appearance of the fur depends largely -upon it. The drum, such as is shown in Fig. 15 is generally made of wood, -or sometimes of wood covered with galvanized iron. The skins together with -fine hardwood sawdust are tumbled for 2 to 4 hours, or sometimes longer. -Occasionally a little asbestos or soapstone is added to the sawdust; for -white, or very light-colored skins, gypsum or white sand is used, either -alone, or in admixture with the sawdust; and for darker skins, graphite or -fine charcoal is sometimes added in small quantities. The drum-cleaning -process polishes the hair, giving it its full gloss and lustre, and at -the same time absorbing any oil or other undesirable matter which may be -adhering to the hair as a result of the washing and tanning processes. -Any soap, or traces of mordant are wiped off and so removed, and by using -heated sawdust, or heating the drum while rotating, the fur acquires a -fullness and play of the hair which are great desiderata in furs. The -sawdust must then be shaken out of the furs. This is done by cageing. In -some instances, the drum itself can be converted into a cage, by replacing -the solid door with one made of a wire screen. (Fig. 16.) Usually, -however, the skins are removed from the drum and put in a separate cage, -which is built like the drum, but has a wire net all around it, through -which the sawdust falls, while the skins are held back. The cages are -generally enclosed in compartments in order to prevent the sawdust from -flying about and forming a dust which would be injurious to the health of -the workers. In large establishments, the drum-cleaning machinery occupies -a large section of the plant, many drums and cages being used, and special -arrangements being made to take care of the sawdust which can be used over -again several times, until it becomes quite dirty. - -[Illustration: FIG. 15. DRUM. (COMBINATION DRUM AND CAGE AS A DRUM.) - -(_F. Blattner, Brooklyn, New York._)] - -[Illustration: FIG. 16. CAGE. (COMBINATION DRUM AND CAGE AS A CAGE.) - -(_F. Blattner, Brooklyn, New York._)] - -With this operation ends the ordinary procedure of fur dressing. But -there are several additional processes required in the treatment of -certain furs, which are generally undertaken by the dresser, and chief -among these are shearing and unhairing. Sometimes this work is done in -separate establishments organized solely for this business. Certain kinds -of furs, among them being seal, beaver and nutria, possess top-hair which -may detract from the beauty of the fur, the true attractiveness being in -the fur-hair. The top-hairs are therefore removed, and for this purpose -machines are now being used. Formerly this work was all done by hand, and -on the more expensive furs like seal and beaver, unhairing is now done on -a machine operated by hand. The principle of the process is as follows: -The skins are placed on a platform and the hair blown apart by means of -a bellows. The stiff top-hairs remain standing up, and sharp knives are -brought down mechanically to the desired depth, and the hair is cut off -at that point. The skin is then moved forward a short distance, and the -process repeated until all the top-hairs have thus been cut out. With -muskrats, or other pelts which do not require such very careful attention, -the whole process is done automatically on a machine. The fur-hair is -brushed apart by means of brushes and a comb, and at regular intervals, -sharp knives cut off the top-hairs. Several hundred skins can be unhaired -in a day on such a machine requiring the attention of only one man. A -machine for unhairing skins is shown in Fig. 17. - -[Illustration: FIG. 17. UNHAIRING MACHINE. - -(_Seneca Machine & Tool Co., Inc., Brooklyn, N. Y._)] - -With other furs, such as rabbits, hares, etc., where the trouble of -unhairing would be too great commensurate with its advantages, the hair -is sheared instead. The top hair is cut down to the same length as the -under-hair by means of shearing machines which can be regulated to cut to -any desired length of hair. A typical device for shearing furs is shown -in Fig. 18. - -[Illustration: FIG. 18. FUR-SHEARING MACHINE. - -(_Seneca Machine & Tool Co., Inc., Brooklyn, N. Y._)] - - - - -CHAPTER VII - -WATER IN FUR DRESSING AND DYEING - - -The assertion has often been made, although its absurdity is now quite -generally realized, that the success of the European fur dressers and -dyers, particularly in Leipzig, is due to the peculiar nature of the -water used, which is supposed to be especially suited for their needs. -The achievements in this country in the fur dressing and dyeing industry -during the past few years are ample and sufficient answers to the claim of -foreign superiority in this field no matter what reason may be given, and -particularly when the quality of the water used is advanced as a leading -argument. For the water employed by the establishments in and about New -York, as well as in other sections of the country is surely not the same -as the water of Leipzig, yet the work done here is in every respect the -equal of, if not better than the foreign products. - -It is interesting to note that similar rumors were current here in the -early period of the development of the American coal-tar industry since -1914. Our efforts to establish an independent dyestuff industry were -doomed to failure, according to those who circulated the stories, because -we did not have the water, which they claimed was responsible for the -German success. The present status of the American dye business, in its -capacity satisfactorily to supply most of the needs of this country and -of others as well, speaks for itself. - -However, as is often the case with such erroneous assertions, there -is just enough of an element of truth in the statement regarding the -peculiar qualities of certain kinds of water, to make the matter worthy -of consideration. Water is certainly a factor of great importance in fur -dressing and dyeing, and it is not every sort of water that is suitable -for use. This fact was recognized by the early masters of the art, for -they invariably used rain-water as the medium for their tanning and dyeing -materials, and their choice must be regarded as an exceedingly wise one. -While the necessity for giving consideration to the quality of the water -for fur dressing purposes is great, it is in fur dyeing that the effects -of using the wrong water are largely evident, and so extra care must be -exercised in the selection of water for this purpose. - -The essential requirements for a water suitable for the needs of the -fur dressing and dyeing industry, are: first, a sufficient, constant -and uniform supply; and second, the absence of certain deleterious -ingredients. Chemically pure water is simply the product of the -combination of two parts by volume of hydrogen with one part by volume -of oxygen. Such water can only be made in the laboratory, and is of no -importance in industry. For practical purposes, distilled water may be -regarded as the standard of pure water. Here, too, the cost and trouble -involved in the production of distilled water on a large scale is -warranted only in a certain few industrial operations. A natural source -of water which in its character most nearly approaches distilled water -is rain. In fact, rain-water is a distilled water, for the sun's heat -vaporizes the water from the surface of the earth forming clouds, which -on cooling, are condensed and come down as rain. Rain-water is usually -regarded as the purest form of natural water. Exclusive of the first -rain after a dry period, rain-water is quite free of impurities, except -possibly for a small percentage of dissolved atmospheric gases, which -are practically harmless, and which can usually be readily eliminated -by heating the water. Moreover, rain-water is quite uniform in its -composition throughout the year in the same locality, and it possesses -all the desirable qualities of a water suited for fur dressing and dyeing -purposes. Formerly when the quantity of water used in the industry -was comparatively small, the supply from rain was sufficient to meet -all the requirements. But now, when tremendous quantities of water are -used constantly, rain-water is no longer a feasible source, and other -supplies must be utilized, although in a sense, all water may be traced -to rain-water as its origin. - -When rain-water falls on the earth it either sinks into the ground until -it reaches an impervious layer, where it collects as a subterranean -pool, forming a well, or continues to flow underground until it finally -emerges at the surface as a spring; or on the other hand the rain-water -may sink but a short distance below the surface, draining off as ponds, -lakes or rivers. In the first case the water is called ground water, in -the latter it is known as surface water. Ground water usually contains -metallic salts in solution, and relatively little suspended matter. If -the water has percolated through igneous rocks, like granite, it may be -quite free even of dissolved salts, and such water is considered "soft." -If, however, the rocky formations over which, or through which, the water -has passed contain limestone or sandstone, or the like, salts of calcium -and magnesium will be dissolved by the water. The presence of the lime -and magnesia salts, as well as salts of aluminum and iron, in the water, -causes it to be what is termed "hard." Surface water is more likely to -contain suspended matter, with very little of dissolved substances. -Suspended matter, like mud, contains much objectionable matter such -as putrefactive organisms and iron, but most of these materials can be -removed by filtration or sedimentation, and seldom cause any difficulties. - -Hardness in water is generally the chief source of trouble when the water -is at fault. Hardness may be of two kinds, either permanent, or temporary, -or sometimes both are found together. Water which is permanently hard -usually contains the lime and magnesia combined as sulphates. Temporary -hardness, on the other hand, is due to the presence of lime and magnesia -in the form of bicarbonates, the carbon dioxide contained in the water -having dissolved the practically insoluble carbonates: - - CaCO{3} + CO{2} + H{2}O = Ca(HCO{3}){2} - calcium carbon water calcium - carbonate dioxide bicarbonate - -Temporary hardness can be eliminated by heating the water, the carbon -dioxide being expelled and the carbonates of lime and magnesia being -precipitated and then filtered off. Both permanently and temporarily hard -waters can be softened by the addition of the proper chemical, such as -an alkaline carbonate like sodium carbonate. This precipitates insoluble -carbonates of the lime, magnesia, iron and aluminum, leaving a harmless -salt of sodium in solution in the water. The sludge is allowed to settle -in tanks before the water is used. - -In fur dressing and dyeing, water is employed for soaking and washing the -skins, dissolving chemicals, extracts and dye materials, and also for -steam boilers. A small amount of hardness in the water is not harmful, -and up to 10 parts of solid matter per 100,000, may be disregarded. -Permanent hardness is particularly objectionable in water for boiler -purposes, as it forms scale. The effect of the impurities of the water -depends on the nature of the chemicals and dyes used. Where acids are -used in solution compounds of magnesium, lime and aluminum will generally -not interfere. Hard water must not be used for soap solutions, as sticky -insoluble precipitates are formed with the soap by the metals, this -compound adhering to the hair, and being difficult to remove, will cause -considerable trouble in subsequent dyeing. An appreciable loss of soap -also results, as one part of lime, calculated as carbonate will render -useless twelve parts of soap. In tanning or mordanting, where salts of -tin, aluminum or iron are employed, hard water should not be used, as lime -and magnesia will form precipitates with them. Bichromates will be reduced -to neutral salts, and cream of tartar will also be neutralized. With dyes -also, hard water has a deleterious effect. Basic dyes are precipitated by -this kind of water, rendering part of the dye useless, and also causing -uneven and streaky dyeings. Sometimes the shades of the dyeings are -modified or unfavorably affected. Considerable quantities of lime and -magnesia in the water will cause duller shades with logwood and fustic -dyeings. The presence of iron, even in very slight quantities generally -alters the shade, darkening and dulling the color. - -These facts were apparently all recognized and understood by the fur -dressers and dyers of an earlier period, for instead of utilizing the -water of lakes and streams near at hand, which afforded a more constant -supply, but which contained harmful impurities, they collected the -rain-water, which was always soft. Whether they realized the nature -and character of the substances that make water hard is uncertain, -but they were always careful to avoid such water. At the present time -establishments located in and about large cities like New York, where -the majority of American fur dressing and dyeing plants are situated, -have no trouble about the water. The cities supply water which is soft, -suitable alike for drinking and industrial purposes. Other plants, not -so fortunately situated, often have to employ chemical means to treat the -water so as to make it suitable for use. - - - - -CHAPTER VIII - -FUR DYEING - -INTRODUCTORY AND HISTORICAL - - -In discussing fur dyeing, the question naturally arises, "Why dye furs at -all? Are not furs most attractive in their natural colors, and therefore -more desirable than those which acquire their color through the artifices -of man?" The answer cannot be given simply. Natural furs of the more -valuable kinds are indeed above comparison with the majority of dyed furs. -Yet there are several reasons which fully justify and explain the need -for fur dyeing, for at the present time, this branch of the fur industry -is almost as important and indispensable as the dressing of furs. - -The first application of dyeing to furs, had for its purpose the -improvement of skins which were poor or faulty in color; or rather, the -object was to hide such defects. As nearly as can be ascertained, this -practise was instituted at some time during or before the fourteenth -century, for fur dyeing seems to have been common during that period, as -is apparent from the verses of a well-known German satirist, Sebastian -Brant, who lived in the latter part of the fourteenth century: - - "Man kann jetzt alles Pelzwerk färben, - Und tut es auf das schlechste gerben." - -However, at a later period, there was a general condemnation of the dyeing -of furs, and among the list of members of the furrier's guilds, none can -be found who are described as dyers. There is a record of a decree issued -by a prince in a German city in the sixteenth century, prohibiting the -practise of fur dyeing. Inasmuch as furs were worn only by the nobility -and certain other privileged classes, and also were very costly, there -was great profit to be had by dyeing inferior skins so as to disguise the -poor color, and then selling such furs at the price of superior quality -skins. This was undoubtedly the reason for the prohibitory decree, but -there were some who continued to practise the forbidden art in secret, -using secluded and out-of-the-way places for their workshops, and mixing -their carefully-guarded recipes with as much mystery as the witches did -their magic potions. These circumstances probably account for the great -amount of mystery which has been, and still is to a considerable degree, -attached to fur dyeing, and also explains the opprobrium and distrust with -which fur dyers were formerly regarded. - -Even at the present time, dyeing is often employed to improve furs which -are faulty in color. It frequently happens, that in a lot of skins there -are some which are considerably off shade, or in which the color is such -as to appreciably reduce their value below the average, the hair being -usually too light a shade, or of uneven coloring. By carefully dyeing -these skins of inferior color, they can be made to match very closely -the best colored skins of the particular lot of furs, and consequently -increase their value. With most of the cheaper kinds of furs, the trouble -and cost of improvement by dyeing would not be worth while today; but with -some of the more valuable furs, and especially such as are very highly -prized, like the Russian sable, or marten, or chinchilla, the darkening -of light skins by the skillful application of fast dyes to the extreme -tips of the hair, will increase their value sufficiently to warrant the -expense. This dyeing or "blending" as it is called in such cases, is done -in such a clever and artistic manner that only experts can distinguish -them from the natural. Dyeing used for such purposes is not objectionable, -provided the skins are sold as dyed or "blended." - -There are certain kinds of furs, such as the various lambs, Persian, -Astrachan, Caracul, etc., which are never used in their natural color, -because it is usually of a rusty brownish-black. These are furs possessing -valuable qualities otherwise, so they are dyed a pretty shade of black, -which brings out the beauty of the fur to the fullest extent. Sealskins -are also dyed always. Formerly they were dyed a deep, rich dark brown, -resembling the finest shades of the natural color, but now the seals are -dyed black with a brownish undertone, a color quite different from the -natural. While these two instances cannot be said to be cases of dyeing -to disguise faulty color, they are examples of improvement of color by -dyeing. - -Closely associated with the use of dyes to increase the value of a fur -by improving its color, is the dyeing of skins of a certain lot of furs -to produce a uniform shade, thereby facilitating or to a considerable -degree eliminating the task of matching the skins by the furrier. This is -usually done only on skins which are quite small, of which a great many -are needed in the manufacture of fur garments, because the matching of -several hundred skins would entail too much time and labor commensurate -with the value of the fur. The most notable instance of the use of dyes to -produce a uniform shade on furs is the case of the moleskin. Occasionally, -furs are dyed after being made into garments, by careful application of -dyes, in order to obtain certain harmonious effects, such as uniformity -of stripe, or to produce a desired gradation of shade among the different -skins comprising the garment. - -Not infrequently, the great variety of shades and color schemes which -Nature provides in the different furs, becomes insufficient to satisfy the -desire of the fur-wearing public for something new. The whims of fashion -always require some novel effect, even though it be for only one season. -To meet this demand for novelty, fantasy or mode shades are produced on -suitable furs,--colors which do not imitate those of any animal at all, -but which, nevertheless, strike the popular fancy. It often happens that -such a color becomes quite popular, and enjoys a considerable vogue, to -the great profit of those who introduced the particular color effect. The -best ones, however, meet with only a comparatively short-lived demand, -being soon superseded by different color novelties. - -The basis, though, of the greatest proportion of fur dyeing at the present -time, is the imitation of the more valuable furs on cheaper or inferior -skins. With the gradual popularization of furs as wearing apparel since -the beginning of the last century, the demand for furs of all kinds -has increased enormously. The supply of furs, on the other hand, and -especially of the rarer kinds, has had difficulty in keeping pace with -the requirements, and as a result there is a shortage. A very effective -means of relieving this shortage, to a great degree, at any rate, is -the dyeing of imitations of the scarcer furs on cheaper skins. There -are many animals among the more common, and more easily obtainable ones, -whose skins are admirably suited as the basis of imitations of the more -costly furs. Some of the furs which are adapted for purposes of dyeing -imitations are marmot, red fox, rabbit, hare, muskrat, squirrel, opossum, -raccoon, and many others, and the imitations made are those of mink, -sable, marten, skunk, seal, chinchilla, etc., and indeed, there are very -few valuable furs, which have not been dyed in imitation on cheaper pelts. -On account of the general mystery which formerly surrounded fur dyeing -establishments, and which has persisted to this day, although to a lesser -degree, many peculiar notions were held, even by those in the fur trade, -concerning the production of imitations. The idea that in order to "make" -a certain fur out of a cheaper skin, it was necessary to use the blood -of the animal imitated, is typical of the conceptions of fur dyeing held -not so long ago. To-day, while the knowledge generally possessed about -this branch of the fur industry is meagre and vague, the air of mystery -and secrecy has become somewhat clarified, and such ideas as are current -about fur dyeing are more rational than formerly. - -The dyeing of imitations is quite an artistic kind of work, and indeed -fur dyeing ought to be classed among the finest of industrial arts. Some -of the reproductions achieved by dyers on a commercial scale are truly -admirable. The possibility of imitating the finer furs on cheaper skins -naturally led to abuse, the dyed furs being passed off frequently on the -unsuspecting and uninformed buyer as the genuine original. In fact, this -practise became so flagrant that in England laws were enacted to remedy -the evil. At the present time, dyed furs are all sold as such, although -there always may be some unscrupulous merchants who seek to profit by -deception. Some of the imitations and the names of the furs for which they -were sold, are as follows: - - Muskrat, dyed and plucked sold as seal - Nutria, plucked and dyed sold as seal - Nutria, plucked and natural sold as beaver - Rabbit, sheared and dyed sold as seal or electric seal - Otter, plucked and dyed sold as seal - Marmot, dyed sold as mink or sable - Fitch, dyed sold as sable - Rabbit, dyed sold as sable - Rabbit, dyed and sheared sold as beaver - Muskrat, dyed sold as mink or sable - Hare, dyed sold as sable, fox, or lynx - Wallaby, dyed sold as skunk - White rabbit, natural sold as ermine - White rabbit, dyed sold as chinchilla - White hare, dyed or natural sold as foxes, etc. - Goat, dyed sold as bear, leopard, etc. - -This list serves to indicate but a few of the great number of -possibilities which are available for the fur dyer to produce imitations -of the better classes of furs. Needless to say, these imitations cannot, -as a general rule, equal the originals, because while the color is one -of the most important features in judging the fur, the nature of the -hair, gloss, waviness, thickness, and also the durability are essential -considerations, and it is only in certain instances that skins used -for imitations approach the originals in these respects. However, for -the purposes and desires of the majority of people who wear furs, the -imitations are deemed quite satisfactory, and they also have the advantage -of being cheaper than the natural originals. - -For whichever reason furs are dyed, there is no doubt that the art of fur -dyeing is one of the most difficult kinds of application of dye materials. -In the dyeing of the various textiles, either as skein or woven fabric, -the material is of a uniform nature, and therefore the dye is absorbed -evenly by the fibres. Moreover, textiles are dyed at, or near the boil, -the dyestuff being more uniformly and permanently taken up from solution -by the fibre at elevated temperatures. - -How different is the case with furs! Far from being homogeneous, furs -present the greatest possible diversity of fibres to be dyed. As already -noted elsewhere, fur consists of two principal parts, the hair and the -leather, differing widely in their actions toward dyes. As a general -rule, the leather absorbs dyestuffs much more readily than the pelage, -and inasmuch as fur dyeing is intended mainly and primarily to apply to -the hair, there is usually an appreciable loss of dye material due to its -being absorbed by the leather, and thereby rendered unavailable for dyeing -the hair. This fact must be taken into account in the dyeing of furs, and -the methods must be adapted accordingly. - -With reference to the hair itself, not only has each class of furs -hair of a different kind, but even in the same group there is always a -considerable divergence in the properties of the hair. The fur-hair, being -more or less of a woolly nature, takes up the dye with comparative ease, -while the top-hair is quite resistant to the action of all dye materials. -As pointed out in the discussion of the nature of fur, on different parts -of the same pelt the hair varies in its capacity for absorbing coloring -matters. The color of the hair, also frequently presents a great variety -throughout the skin, both in fur-hair and top-hair. Yet with all this lack -of uniformity and homogeneity, the dyed fur must be of an even color, -closely approaching the natural, gently graded and without any harsh or -unduly contrasted effects. The natural gloss of the hair, one of the most -valuable qualities of the fur, must be preserved. This is by no means -a simple matter, for the luster is affected by dyes and chemicals with -comparative ease, and especially careful treatment is necessary to prevent -any diminution of the gloss. - -When the leather part of the fur is exposed to solutions of a temperature -exceeding 40°-50° centigrade, it soon shrivels up or shrinks, and on -drying the pelt, becomes hard and brittle, and therefore quite useless. -Methods of fur dyeing have to take into consideration this fact, and the -temperature of the dyebath must not be greater than 35°-40° centigrade. To -be sure, certain dressings make furs capable of withstanding much higher -temperatures, but their applicability is not universal, being suited only -for a very limited special class of dyestuffs. (V. Fur Dressing). The -necessity for employing comparatively low temperatures, coupled with the -great resistance of the hair to the absorption of dye, even at much higher -temperatures, makes fur-dyeing a very difficult operation indeed. Another -obstacle which must be surmounted, is the possibility of extraction by -the dye solution, of those materials, chemical or otherwise, which are -contained in the leather, and which are the basis of its permanence, -softness and flexibility. For in the majority of dressing processes, the -action of the ingredients is a preservative one, and when these are wholly -or partially removed from the leather during the dyeing, it becomes, on -drying, hard and horny, like the original undressed pelt. In cases where -furs are to be dyed, special dye-resisting dressings must be used, or the -dyed skins must receive an additional dressing before drying. - -Dyeings on furs, to have any value, must possess great fastness to light, -rubbing and wear, and must not change color in time, either when the furs -are stored, or when made up into garments. The necessity for fur dyeings -to have these properties, together with the difficulties outlined above, -has greatly limited the field of available dyeing materials, as well as -the methods of application. These will now be taken up in detail. - - - - -CHAPTER IX - -FUR DYEING - -GENERAL METHODS - - -Before the furs can be dyed, they have to undergo certain preparatory -processes: first, killing, which renders the hair more susceptible to the -absorption of the dye; and second, mordanting, which consists in treating -the killed fur with chemicals which help the dye to be fixed on the hair. -Then the skins are ready to be dyed. - -There are two principal methods by which dyes are applied to furs in -practise: the brush process, whereby only the tips or the upper part -of the hair are colored; and the dip process, whereby the entire fur, -including the leather is dyed. All other procedures in fur dyeing -are modifications or combinations of these two. Killing solutions and -mordanting solutions are also applied by one of these methods, usually -the dip process, although very frequently combinations of the brush and -dip methods are used. - -Chronologically the brush method of dyeing came first. The early masters -of the art were extremely fearful about employing any means by which -there was a possibility of the leather being in any way affected. They -naturally had to devise such methods as would give the desired effect -in a satisfactory manner, and as would be confined solely to the hair -part of the fur, leaving the leather untouched. By applying the dye -or other material to be used, in the form of a paste with a brush, the -upper portion of the hair only was treated. For different kinds of furs -different sorts of brushes were used, and the depth to which the hair was -colored could be controlled by skillful manipulation of the brushes. It -was frequently necessary to give a ground color to the hair, the lower -part being dyed a different shade from the tips. This was accomplished -by spreading the dye paste over the hair with a broad brush, and then -beating the color in with a specially adapted beating brush. With larger -furs, two skins were placed hair to hair after the dye had been brushed -on, and the color forced to the bottom of the hair by a workman tramping -on the skins. The dyeing of seal was a typical illustration of these -procedures. First the tips of the hair were dyed. The color was brushed -on, allowed to dry, then the excess beaten out with rods. These operations -were repeated until the proper depth of shade was obtained, often as many -as a dozen or more applications of the dye being necessary. Then the base -color was spread over the hair, and beaten or tramped in until the lower -parts of the hair were penetrated. This process also required drying and -beating out of the excess dye, as well as numerous applications of the -dye to impart the desired color to the hair. Prior to the dyeing, the furs -were killed, by brushing on a paste containing the essential ingredients, -drying and beating and brushing the fur, just the same as in dyeing. It -will be readily seen that such methods were exceedingly laborious, and in -some cases the dyeing took many weeks, and even months. - -It was quite a step forward when a certain fur dyer, possessing a little -more courage, or perhaps, experimenting spirit than the others, attempted -to dye furs by dipping them entirely into a bath containing a solution -of the dye instead of applying a paste as formerly. The advantages to be -gained by such a method of dyeing were many. A large number of skins could -be treated thus at one time, and this was a very important consideration -in view of the great increase in the demand for dyed furs. By allowing the -furs to remain in the dye solution until the proper shade was obtained, -the time and labor of applying many coats of dye by brush was considerably -reduced, and in addition, there was a greater probability of the products -coming out all alike, uniformly dyed. The results as far as the hair -was concerned, were indeed highly gratifying, but the condition of the -leather after dyeing was not so encouraging. This difficulty has to a -considerable degree been overcome, although there are frequent instances -of the leather being affected by the dyeing process even with modern -methods. However, the remedy in such cases, or rather the preventative -is the proper dressing of the skins prior to the dyeing. The dip method -of dyeing has acquired great importance, and is being employed in dyeing -operations involving the handling of millions of skins annually. In -certain instances, nevertheless, the brush method is of prime significance -as in the dyeing of seal, and seal imitations on muskrat and coney, -enormous quantities of furs being dyed in this fashion. In the majority -of imitations dyed, both the brush and the dip methods must be used. - -Figure 19 illustrates the various types of brushes which are used at the -present time for the application of the dye by the brush method. Each -brush has a specific purpose and use. The procedure in brush dyeing is -somewhat as follows. The skins, after being properly treated, that is, -killed, and mordanted, are placed on a table, or work-bench, hair-side up. -Then by means of a brush which is adapted to the nature and requirements -of the particular fur, the solution is brushed on in the direction of -the fall of the hair, occasionally beating gently with the brush so as to -cause the dye to penetrate to the desired depth. Considerable skill and -care must be exercised in this operation as it is rather easy to force -the dye down further than is wanted, and in some cases the leather or the -roots of the hair may be affected. The skin having received its coat of -dye, is then dried and finished, if no other dyeing processes are to be -applied. Frequently, with certain types of dyes, several applications of -color are necessary, and these are brushed on as the first one, drying -each time. Then, on the other hand, the skin may receive a dyeing in the -bath by dipping, and for this also, the fur is first dried after the brush -dyeing. - -[Illustration: FIG. 19. BRUSHES USED IN FUR DYEING BY THE BRUSH METHOD.] - -Quite recently, owing to the great quantities of furs which are being -dyed as seal imitations, chiefly by the brush method, although the dip -method is used in conjunction with it, machines have been invented to -replace the hand brush, and the dye is now applied mechanically. Machines -for this purpose are by no means new, there being records of inventions -almost a score of years past, but they did not achieve much success. -Brush-dyeing machines, to be efficient, must be designed to suit the -needs of the particular type of fur to be dyed, otherwise there will be -a great lack of uniformity in the dyed skins, a condition which cannot -occur when the dye is brushed on by hand brushes. Figure 20A and B shows -diagrammatically, machines invented within the past few years, which are -used to dye mechanically furs by the brush process. - -[Illustration: FIG. 20. TYPES OF MACHINES FOR DYEING FURS BY THE BRUSH -METHOD. - -_A._ (U. S. Patent 1,225,447.) _B._ (U. S. Patent 1,343,355.)] - -[Illustration: FIG. 21. DRUM FOR WORKING WITH LIQUIDS. - -(_Turner Tanning Machinery Co., Peabody, Mass._)] - -For the dipping process, the dye solution is prepared in vats, or -liquid-tight drums, or in some instances in paddle arrangements. The -skins are placed in the dye-bath, and the dyeing operation proceeds -without any difficulty. After the proper shade is obtained, the furs -are removed, washed free of excess dye, dried and finished. The dipping -method is employed where a single shade is to be dyed on the fur, as the -production of blacks on lambs. But in most cases, the dyeing in the bath -is supplemented by the application of a coat of dye by the brush to the -upper part of the hair, the color being usually a darker shade than the -ground dyeing. Thus, for example, in the dyeing of imitation sable on -kolinsky or a similar fur, the skins are first dyed the relatively light -color of the under-hair by the dip process, then the dark stripe effect -is brushed on. - -The blending of sables, martens, chinchillas or other rare furs, is not -done in the same manner as with other furs, because each skin requires -individual attention and a long and careful treatment. The dye solution -is applied by means of very fine brushes or sometimes feathers, to the -extreme tips of the hair, until the proper degree of color intensity is -obtained. The time, labor, and skill necessary for this sort of work are -warranted only in the case of the highest-priced furs, and the blendings -are so excellent as to defy detection, except by experts. - -[Illustration: FIG. 22. DEVICE FOR CONVEYING SKINS. - -(_Turner Tanning Machinery Co., Peabody, Mass._)] - -After the furs have gone through all the operations required by the -processes of killing, mordanting, dyeing and washing, they are ready to -be dried and finished. The procedure is quite similar to that employed in -fur dressing. Sometimes the leather side of the skins is brushed with a -strong salt solution before drying, in order to replace some of the salt -which was extracted during the dyeing processes. In other instances, a -light coat of some oily substance is brushed on, to render the leather -soft and flexible after drying, where there is a possibility of the skins -turning out otherwise. Great care must be exercised in the handling of -the dyed skins to avoid the formation of stains or spots on the hair, -which might ruin the dyeing. As little handling of the furs as is feasible -will reduce any trouble from this source. In conveying the wet skins -from one part of the plant to another it is desirable to use a device -such as is shown in Fig. 22. For drying, the same machines as described -under Fur Dressing can be used, and similar care must be taken to avoid -overheating or irregularity of drying. Drum-cleaning constitutes a very -important operation in the finishing of the skins, the hair receiving -a polish, and the full lustre and brilliancy of the dye being thereby -brought out. Then after caging to remove the sawdust or sand, the skins -are passed over the staking knife, or are treated in a machine suited -for the purpose, to stretch them and to render them thoroughly soft and -flexible. And therewith is concluded the work of the fur dyer proper, and -the skins are ready to return to the furrier, in whose hands they undergo -the metamorphosis into the fur garments to be worn chiefly by the feminine -portion of humanity. - - - - -CHAPTER X - -FUR DYEING - -"KILLING" THE FURS - - -If dressed furs are treated with a paste or solution of a dye properly -prepared, and at the right temperature, the hair will show very little -tendency to absorb the coloring matter. Even after prolonged treatment -with the dye, only a small amount will be taken up by the hair, and in a -very irregular fashion. Soft, woolly hair, like that of lambs and goats -will be colored more easily than that of furs with harder hair, and the -under-hair of a fur will generally have a greater affinity for the dye -than the harder and stiffer top-hair. Moreover, in some parts of the same -fur, the hair will absorb more color than in other parts. In other words, -the hair of furs resists the action of dye materials to a greater or less -degree, depending upon the character of the fur, and also upon the part -of the pelt. In order to overcome this resistance of the hair, and to -render it uniformly receptive to the coloring substances, the furs are -treated with certain chemical agents, the process being known technically -as "killing." - -The origin of the term is obscure, but it is interesting to note that -in the fur dyeing countries other than the United States and England, -the corresponding expression is used: in Germany, "töten," and in France -"tuer." The explanation of the process is as follows: The surface of the -hair is covered with a fine coat of fatty material which renders the hair -more or less impervious to dye solutions and solutions of other substances -which may be used for dyeing purposes. This fatty coating of the hair -cannot be removed by mechanical means, otherwise the hair would have -been freed of it during the dressing operations. Chemical solvents must -therefore be resorted to, and naturally alkaline materials are used, these -being usually cheapest and also most effective in their dissolving action -on fatty substances. Alcohol, ether, benzine, and other similar liquids -also serve as killing agents on furs, since they too, are fat solvents. -In all these cases, the fatty substance on the hair is dissolved away, -and the protective coat which previously rendered the hair impervious -to the dye, is now removed. There are certain chemicals however, which -normally do not dissolve substances of a fatty nature, but are strongly -oxidizing, such as peroxide of hydrogen, hypochlorites, permanganates, -perborates, nitric acid, etc., and exert a killing action when they are -applied to the hair, in that the hair is made capable of taking up the -dye from its solutions. In this case the killing can hardly be said to -be due to a degreasing process. The fact that killing can be brought -about with other substances than alkalies or fat solvents, has led to -the belief on the part of some investigators in this field that killing -is more than a degreasing operation, although the removal of the fatty -material of the hair undoubtedly takes place. Some authorities consider -that the killing process changes the pigment of the hair, which thereby -becomes more receptive to the dye. It is quite possible that some such -change in the structure of the hair fibre does take place, the surface -of the hair becoming slightly roughened, and therefore more capable of -fixing the coloring matter. The question is still an open one, and since -no conclusive researches have been made as yet, it will be assumed that -killing is simply a degreasing process, inasmuch as the modern practise -is based on this supposition, and very satisfactory results are obtained. - -An account of the historical development of the killing process brings -out many interesting and enlightening facts, so it will be given here -briefly. One of the first substances used for killing, or degreasing the -hair of furs, was decomposing urine. Urine contains about 2% of urea which -gradually changes to salts of ammonia, and in the presence of the air, -largely to ammonium carbonate. This substance has a weak alkaline action, -but sufficiently effective to be used for killing the hair of certain -types of furs. Woolly furs, such as those derived from the various kinds -of sheep and goats, were degreased with stale urine, the skins being -washed in this, and then rinsed in water. The fat was emulsified by the -ammonium carbonate present, and could thus be easily removed. For other -furs, a stronger mixture was necessary. An example of a killing formula -used on wolf, skunk and raccoon, which were to be dyed black, is the -following: - - 350 grams beechwood ashes - 200 grams unslaked lime - 150 grams copper vitriol - 100 grams litharge - 60 grams salammoniac - 40 grams crystallized verdigris - 3.5 liters rain water - -Beechwood ashes were a very important constituent of the old killing -formulas. The reason for that lies in the fact that beechwood contains -a comparatively high percentage of potassium, which occurs in the ashes -of the burned wood as potassium carbonate, or potash. The ashes alone -were frequently used, being applied in the form of a paste, which in -some instances had an advantage over a solution, in that the killing -could be limited to certain parts of the skin where it was more desired -than in other parts. By extracting the wood ashes with hot water, and -evaporating the clear solution to dryness, potash could be obtained, which -was considerably stronger than the original ashes. Next in importance -for the killing was unslaked lime. This substance was also often used by -itself, being first slaked with water, and using the milk of lime thus -formed, after cooling. Salammoniac, although a salt, and consequently -without any killing action, in contact with the beechwood ashes or the -lime in solution or paste, liberated ammonia slowly, and so also acted -as a degreasing agent. The other chemicals in the formula took no part -in the actual killing of the hair, but acted either as mordant materials -or as mineral dyes. The copper salts, in this mixture present in two -forms, as sulphate in copper vitriol, and as acetate in the verdigris, -were important constituents of the dye formula, being essential to the -production of the proper shade. These substances properly had no place -in the killing formula. The litharge, also was not a killing agent, but -in the presence of the alkaline materials of the killing mixture, it -gradually combined with the sulphur contained in the hair, forming lead -sulphide, and thereby darkening the color of the hair. In this case, -the metallic compound acted, not as a mordant, but as a mineral dye. The -mixture was applied to the hair by means of a brush, the skins let lie for -some time, then dried, brushed and beaten. Many applications were usually -necessary to sufficiently degrease the hair. Inasmuch as the killing paste -was prepared by mixing the constituents together, and then was brushed -on at the comparatively low temperatures which the proper protection of -the hair required, it is questionable whether some of the metal compounds -were even enabled to act as described above as mordant or dye. In spite of -the trouble and considerable time required in working with such a killing -formula to obtain the hair in the desired condition for dyeing, the use -of such a mixture nevertheless possessed the advantage that the hair was -only very slowly and gradually acted upon, and so the gloss was preserved. -The action of strong alkaline substances acting quickly is more or less -detrimental to keeping the gloss of the hair, while the slow action of -the weak alkaline paste of the old formulas, and the gradual formation -of a protective metal film on the surface of the hair, rendered the hair -suitably receptive to the dye which was subsequently applied, without in -any measure affecting the lustre of the hair. - -It would be needless to describe or discuss any more of the old killing -formulas, for the principle involved was the same in all cases, there -being usually a slight variation in the content of metallic salts, -beechwood ashes and unslaked lime being constituents of the great majority -of the mixtures used. Modern killing processes employ substances quite -similar to those of the old formulas, the operations, however, being much -less laborious and less time-consuming, and the cheap, pure products -which chemical science has been able to develop being used in place of -the crude products crudely obtained from natural sources. The chemicals -used at the present time for killing furs, are chiefly ammonia, soda ash, -caustic soda, and caustic lime. The choice of the killing agent depends -upon the nature of the fur, the hair of some furs being sufficiently -killed by treatment with weak alkalies, while in other furs the hair may -require stronger treatment. The ability of the hair of a particular fur to -withstand the action of the different alkaline substances must be taken -into consideration, there being a great divergence in this regard among -the different classes of furs. Raccoon, for example, is not appreciably -affected by a solution of caustic soda of 5 degrees Beaumé, while some -wolf hair cannot withstand the action of a solution of soda ash of less -than 1 degree Beaumé. Frequently much stronger alkalies are necessary to -kill the top-hair than the under-hair, so this accomplished by treating -the skins in a solution which is suited to kill the under-hair, and -subsequently the top-hair is treated with a stronger solution, this being -applied by the brush method. - -Uniformity of action of the killing material on all parts of the skin, -and on all the skins of a given lot, is absolutely essential to obtaining -satisfactory results in dyeing. And it is by no means a simple matter -to get such uniformity, considering the numerous factors that must be -taken into account. Any operation involving the immersion of the skins -in solutions or even in water alone, has an effect on the leather side of -the skin, inasmuch as some of the tanning materials may be extracted. The -application of some substance of a fatty nature to a great degree prevents -this, and the skin can be killed, mordanted and dyed, and then come out -soft and flexible. But the great majority of substances of a fatty nature -are affected by alkalies, and so when the skins are being killed, the -action of the alkaline materials would be upon the fat contained in the -leather as well as that upon the hair. As a result the hair may not be -sufficiently killed, and so give uneven dyeings subsequently. Either a -certain excess of the killing chemical must be used, and it would be very -difficult to ascertain what quantity would suffice, or the killing action -must be prolonged; but best of all, in oiling the skins, an inert mineral -oil should be used, since it is wholly unaffected by alkalies. - -Skins may be killed by the brush process or the dip process, or by both. -For brush killing, the stronger alkalies like lime and caustic soda are -used, the solution being applied to the top-hair with a suitable brush, -and the skins allowed to remain hair to hair for the necessary length -of time, after which they are treated further as skins killed by the dip -process. By this latter process, the furs are immersed in a solution of -the desired killing agent in a vat, or drum, or other appropriate device -which will permit of uniform action of the alkali on the hair of all the -skins. After remaining in the solution the required length of time, the -skins are drained, and rinsed in fresh water, and then entered into a weak -solution of an acid in order to neutralize any remaining alkali, it being -easier to wash out acid than alkali. The furs are then washed thoroughly -in clear water, preferably running water, to remove the last traces of -acid. The skins are then drained and hydro-extracted, or pressed, and are -then ready for the subsequent operations of mordanting and dyeing. - - -KILLING WITH SODA - -Soda is sodium carbonate, which is produced commercially in a very pure -state in several different forms, the chief being sal soda, which is -crystallized sodium carbonate, containing about 37% of actual soda; and -soda ash, or calcined soda, which is anhydrous sodium carbonate. The -latter is the variety most commonly used. - - 10 grams soda ash are dissolved in - 1 liter of water at 25°-30° C. - -The skins are immersed for 2-3 hours, after which they are rinsed and -treated with - - 10 grams acetic acid dissolved in - 1 liter of water. - -The skins are again thoroughly washed, and then hydro-extracted. - - -KILLING WITH LIME - -Lime, calcium oxide, forms a white, amorphous, porous substance, which -readily takes up water, giving calcium hydroxide, or slaked lime. Only the -best grades of lime should be used, as it is very frequently contaminated -with calcium carbonate and other inert materials. - - 10 grams of lime are dissolved in - 1 liter of water. - -The skins are entered, and allowed to remain for a period of time which -varies according to the nature of the fur. During the killing, the -solution must be agitated, in order to evenly distribute the milk of lime, -which has a tendency to settle out. After rinsing, the skins are "soured," -by treating with weak acetic acid solution, then thoroughly washed, and -drained. - - -KILLING WITH CAUSTIC SODA - -Caustic soda is used only on furs the hair of which is very hard and -resistant to killing. Usually it is applied by the brush process, but in -some instances, the dip method must be used. In order to reduce as far -as possible, the action of the caustic soda on the leather, the weakest -permissible solutions are used, increasing the time of treatment, if -necessary. Caustic soda is a white, crystalline substance, occurring -in commerce in lumps, but more conveniently in a solution of 40 degrees -Beaumé, containing 35% of caustic soda. Various quantities, ranging from -4 to 25 grams of this solution per liter of water are taken, according to -the character of the fur, and the skins treated for 2-3 hours, although -weaker solutions may be used, and increasing the duration of the killing. -By keeping the solution in motion, by means of a stirrer or any other -method of agitation, the best results are obtained. After the skins are -sufficiently killed, they are soured, and washed as by the other killing -methods. - -Where the nature of the hair of the fur is such that the top-hair and -the under-hair require different killing treatments, the skins are first -killed by the dip process, with an alkali suited to kill the under-hair, -then a brush killing with a stronger alkali is applied to the top-hair. -The subsequent treatments are the same as for usual dip-killing methods. - - - - -CHAPTER XI - -FUR DYEING - -MORDANTS - - -The hair of furs has the peculiar quality of fixing the oxides or -hydroxides of certain metals from dilute solutions of their salts. -Advantage is taken of this property to mordant the furs, that is, to cause -a certain amount of the metallic oxide or hydroxide to be permanently -absorbed by the fibres. The term mordant comes from the French word -"mordre," meaning to bite, it being formerly considered that the purpose -of a mordant was to attack the surface of the hair in such a way as to -permit the dye to be more easily absorbed. In fact, killing mixtures, -which were intended for this same object, used to contain the various -chemicals which have a mordanting action, in addition to the alkaline -constituents. The mordants were not applied as such, but always as -killing materials. It was later realized, however, that the mordant was -instrumental in the production of the color itself. - -Mordanting may be considered as having a two-fold object: first, to help -fix the dye on the fibre in a more permanent fashion, thus rendering the -dyeings faster; and secondly, to help obtain certain shades of color, as -the various mordants produce different shades with any given dye. Some -classes of dyes can be applied to furs without the use of mordants, but -other types are taken up only in a very loose manner, being easily washed -out from the hair with water, and it is only when such dyes are brought on -to the hair in the form of a metallic compound, producing what is known as -a "lake," that really fast dyeings are obtained with them. The substances -which are used for mordanting the hair are certain metallic compounds, -but not all metallic salts which are used in dyeing are mordants. -Sometimes such a compound is employed to develop the color of the dyeing -by after-treatment, as in the case of after-chroming, the action of the -metallic salt being directed only to the dye, and is not fixed by the -fibre as a mordant must be. In order for a metallic compound to act as a -true mordant, it must be fixed by the hair, and it must combine with the -dye, thus forming a sort of connecting link between the dye and the hair. -It is not absolutely essential that the mordant be applied first, although -this is the customary and commonest practise. There are three ways by -which the mordants can be fixed on the fur hair: First, by the absorption -of the metallic oxide or hydroxide from a solution of the mordant prior to -the dyeing; second, the mordant may be fixed on the fibre at the same time -as the dye; and third, the mordant may be applied after the fur has been -treated with the dye. The last two methods will be discussed in connection -with the dyes, as they are special cases. - -The salts of metals which are comparatively easily dissociated in water, -with the formation of insoluble oxides or hydroxides, are most applicable -as mordants for furs, and among them are compounds of aluminum, iron, -chromium, copper and tin. The constituents of the hair seem to bring -about the dissociation of the metallic salt, and the oxide or hydroxide -as the case may be, is absorbed and firmly fixed by the hair. Just what -the manner and nature of this fixation are, is still uncertain. It is -supposed that chemical combination takes place between the hair and the -metal. The course of this process may, as far as is known, be described -as follows, taking, for example, the case of chromium sulphate: In dilute -solution, this compound gradually dissociates first into its basic salts, -and finally into the hydroxide, the breaking up of the neutral salt being -induced by the presence of the fur-hair. - - Cr{2}(SO{4}){3} + 2H{2}O = Cr{2}(SO{4}){2}(OH){2} + H{2}SO{4} - chromium water first basic sulphuric - sulphate chrome salt acid - - Cr{2}(SO{4}){2}(OH){2} + 2H{2}O = Cr{2}(SO{4})(OH){4} + H{2}SO{4} - second basic - chrome salt - - Cr{2}(SO{4})(OH){4} + 2H{2}O = Cr{2}(OH){6} + H{2}SO{4} - chromium - hydroxide - -These reactions take place within the fibre, after the hair has been -impregnated with the solution of the neutral salt, and when the compound -has been rendered completely basic, in other words has reached the form of -the hydroxide, it is supposed to combine with the acid groups contained -in the hair substance, forming thus some complex, insoluble organic -compound of the metal within the hair. According to some authorities the -mordant is supposed to be present in the hair simply as the hydroxide, -being tenaciously held by some physical means. The facts seem to indicate, -however, that the metal is actually combined in some chemical way with the -hair. For, if the mordant were present as hydroxide, then on white hair it -would show the color of the hydroxide, which it does not. The same facts -obtain with regard to other metals. - -In order for the hair to be properly mordanted, it is necessary that -the metallic compound which is taken up by the hair be held in such a -manner that the mordant cannot be removed by water or even dilute acids -or alkalies. Salts which dissociate too readily produce mordants which -are only superficially precipitated on the hair and subsequently come -off. Usually some substance is added to the solution of the salt to -cause slower and more even dissociation of the salt, so that the hair -substance can be quite saturated with the metallic compound before any -insoluble precipitate is formed. Dilute sulphuric acid, organic acids like -acetic and lactic, and cream of tartar are used to facilitate the uniform -absorption of the mordant salt by the hair. - -When the skins are mordanted before dyeing, they are immersed for 6 to -24 hours in a solution containing 1 to 20 grams of the metallic salts per -liter of water, together with the corresponding quantity of the assistant -chemical. The skins should be so entered into the mordant solution that -the hair is uniformly in contact with the solution, and all the skins -so that they are acted upon alike. Machinery such as is used for killing -is suitable for mordanting also. The duration of the mordanting, and the -concentration of the solutions are varied according to the depth of shade -required, and also according to the nature of the dye to be employed. By -suitably combining several mordants a considerable range of colors can be -obtained with a single dye. - -The various chemicals used as mordants are essentially the same no matter -for which class of dyes they are used, there being only slight differences -in the concentrations of the solutions, the manner of application of -the mordants being practically the same. It is interesting to note that -with the exception of chromium compounds, which are of comparatively -recent adoption as mordants, all the chemicals now used for mordants -were employed by the earliest masters of the art of fur dyeing. While -some of the formulas used by those dyers display a lack of appreciation -of the true action and function of the mordanting chemicals, yet it is -quite remarkable that they chose, in spite of their limited knowledge of -chemical processes and phenomena, just those materials which do act as -mordants if properly applied. The most important metallic compounds for -mordanting furs at the present time are salts of aluminum, iron (ferrous), -copper, tin and chromium (as well as chromates and bichromates). The -compounds of the metals with organic acids such as acetic acid are -preferable, being more easily dissociated, and also leaving in solution -an acid which is less injurious to the fur than a mineral acid. However, -sulphates and other salts of the metals are also used extensively, -inasmuch as they are cheaper than the organic salts. - - -ALUMINUM MORDANTS - -Chief among the aluminum mordants are the various kinds of alum, which is -a double sulphate of aluminum and an alkali such as sodium, potassium or -ammonium. All these salts except that of sodium, form large, colorless, -octahedral crystals, and are soluble in about 10 parts of cold water, -and 1/4 part of hot water. Sodium alum is even more easily soluble, but -on account of the difficulty of obtaining it in crystalline form, it -is little used. The common commercial alum is the potassium aluminum -sulphate. - -Recently, aluminum sulphate has to a large extent replaced alum for -mordanting purposes, because it can be obtained very cheaply in pure form, -and it contains a greater amount of active aluminum compound than does -alum. Only the iron-free salt, however, may be used for the needs of fur -dyeing. - -Aluminum acetate also finds extensive application as a mordant in fur -dyeing, and while somewhat more expensive than the alum or aluminum -sulphate, it has the advantage over these compounds of being combined -with an organic acid, which is preferable when the action on the hair and -leather is considered. Aluminum acetate can be obtained in the market in -the form of a solution of 10 degrees Beaumé, but can also be prepared very -easily as follows: - - 665 grams pure aluminum sulphate, or - 948 grams potassium alum, are dissolved in - 1 liter of hot water. - 1137 grams of lead acetate (sugar of lead) are also dissolved in - 1 liter of hot water. - -The two solutions are mixed, and thoroughly stirred. A heavy white -precipitate forms, which is filtered off, and discarded after the solution -has cooled. The aluminum acetate is contained in the filtrate, and the -solution is brought to a density of 10 degrees Beaumé by the addition of -water, if necessary, and is preserved for use in this form. - - -IRON MORDANTS - -Ferrous sulphate, iron vitriol, or copperas, as it is commonly known, -forms pale green crystals, which on exposure to air lose water, and -crumble down to a white powder. It is very soluble in both cold and -hot water, but the solutions oxidize very rapidly, turning yellowish, -and should therefore be used immediately. Care must be taken that a -good quality of iron vitriol be used for the mordant, otherwise very -unsatisfactory results will be obtained. - -Ferrous acetate is prepared in a manner similar to the aluminum acetate, -and is occasionally employed instead of the ferrous sulphate. Inasmuch, -however, as the solution of ferrous acetate is very easily oxidizable -when exposed to the air, a more stable form is used, and this comes on -the market as iron pyrolignite or iron liquor. This can be prepared by -dissolving iron in crude acetic or pyroligneous acid, or by treating a -solution of iron sulphate with calcium pyrolignite. Iron liquor is really -a solution of ferrous acetate that contains certain organic impurities -which prevent, or rather, considerably retard the oxidation of the iron -salt, but which in no way interfere with its mordanting properties. The -commercial product can be had in various concentrations, but 10 degrees -Beaumé is the most usual and most convenient. - - -COPPER MORDANTS - -The most important copper salts used in fur dyeing processes are copper -sulphate, or blue vitriol, occurring in large blue crystals, very soluble -in cold and in hot water; and copper acetate, which is formed by treating -a solution of copper sulphate with a solution of the requisite quantity -of lead acetate. Copper acetate can also be obtained in the form of -blue-green crystals, very soluble in water, the solution becoming turbid -on prolonged heating, due to the formation of a greenish basic copper -acetate. This insoluble compound is known commonly as verdigris, although -it is not usually produced in the manner mentioned. Numerous fur dyeing -formulas contain verdigris, but inasmuch as the basic copper acetate is -insoluble and thus incapable of reacting with any of the substances used -in dyeing, it is assumed that the soluble normal copper acetate was meant, -for this compound is also sometimes called verdigris. - -In addition, there must be mentioned here a compound which formerly found -extensive use in fur dyeing. This is a double salt of copper and iron, -analogous to alum, ferrous copper sulphate, known as blue salt. It is very -seldom used at the present time, being more effectively replaced by other -substances. - - -CHROMIUM MORDANTS - -The typical chromium mordant is chrome alum, which is a potassium or -ammonium chromium sulphate, constituted just like the aluminum alums, and -forming crystals like these. More frequently used, nevertheless, than the -chrome alum, is chromium acetate, which is prepared from it, either by -treating a solution of the chrome alum with a solution of lead acetate, -or in the following manner: - - 50 grams of chrome alum are dissolved in - 500 cubic centimeters of boiling water. To this is added - 15 grams of 20% ammonia, diluted with 15 grams of water. - -The precipitate which forms is filtered off, and preserved, the filtrate -being discarded. After thoroughly washing the residue on the filter it is -dissolved in dilute acetic acid, heating if necessary, to effect solution. - -Other chromium compounds of an entirely different type are also used in -fur dyeing, these being chromates and bichromates, the latter finding -greater application than the former. Sodium bichromate is the salt most -usually employed. This forms orange-red crystals which are very soluble -in water, and in addition to its use as a mordant it also serves as an -oxidizing agent for developing or fixing certain dyes on furs. - - -TIN MORDANTS - -Compounds of tin find only limited application in fur-dyeing, the only one -of importance being tin salts, stannous chloride, which occurs in the form -of white, hygroscopic crystals, which must be preserved in closed vessels. -It is very soluble, but in dilute solutions it readily forms a basic salt, -so stannous chloride is usually used in very concentrated solutions. - - -ALKALINE MORDANTS - -After the furs have been treated with the solution of some alkali for the -purpose of killing the hair, they are always passed through a slightly -acidulated bath to remove any alkali which may still be adhering. This -operation must always be gone through before the skins can be mordanted -or dyed, for if it were neglected, very uneven and uncertain results -would be obtained. This process, however, entails the expenditure of -no small amount of time, labor and chemicals when large lots of skins -are being handled. In order to eliminate this extra step of "souring" -between killing and mordanting or dyeing, it has been proposed to use -alkaline mordants which combine the killing and mordanting functions, -and accomplish these two processes at the same time. The advantages of -employing such mordants are easily apparent. Cumbersome manipulation and -handling of the skins, with the attendant consumption of much time and -labor are reduced to a minimum, and besides there is no needless waste of -chemicals as is the case in the ordinary methods of killing the furs. - -The principle of alkaline mordants is not a strictly new one. If it -be remembered that the old killing formulas used by the fur dyers of -an earlier age, contained metallic salts with mordanting properties in -addition to the alkaline substances, which alone were effective as killing -agents, it would seem that the suggested alkaline mordants were merely a -revival in modified form of the old processes. This is undoubtedly true -in a large measure, for the killing mixtures which the old masters used -certainly embodied the fundamental principle of simultaneous killing and -mordanting, although it was not recognized at that time. - -Modern alkaline mordants have therefore been devised which can be employed -for killing and mordanting furs at the same time. They are prepared as -follows: - - -ALKALINE ALUMINUM MORDANT - - 250 grams of potassium alum are dissolved in - 1 liter of boiling water. To this solution is added - 300 grams of soda ash, previously dissolved in - 750 c.c. of water, and the resulting precipitate is filtered off, - washed and pressed, and then dissolved in a solution of 65 grams - of caustic soda in 1 liter of water. - - -ALKALINE CHROMIUM MORDANT - - 250 c.c. of chrome acetate mordant of 20 degrees Beaumé - 320 c.c. of caustic soda solution of 38 degrees Beaumé (32.5%) - 10 c.c. of glycerine 30 degrees Beaumé (95%) - -The solution of these substances is brought up to a volume of 1 liter by -the addition of 420 c.c. of water. - - -ALKALINE IRON MORDANT - - 138 grams ferrous sulphate are dissolved in - 362 c.c. of warm water. Cool and add - 25 c.c. of glycerine. Then slowly and carefully add - 25.5 c.c. of concentrated ammonia, taking care that no precipitate - forms. - -While these alkaline mordants seem to have much in their favor, there -are certain possible objectionable features which must be considered. -The solutions of the mordants are generally very alkaline, and not every -fur can withstand more than a limited quantity of alkaline substance -for longer than a comparatively short time. Suitable mordanting usually -requires a longer time than killing does, so with the use of the alkaline -mordant, if the skins remain in the solution until sufficiently killed, -they may be insufficiently mordanted, while if the furs are treated long -enough to be properly mordanted, the hair may have been over-killed. -However, the idea of the alkaline mordant is a good one, and it is -only a matter of time and patient, scientific experimentation when the -difficulties of the method will be eliminated, and a much-desired process -will become a practical realization. - -The general methods for applying the various mordants of all sorts follow -closely the procedure adopted for the killing formulas, and similar -precautions must be observed, in order to obtain consistently uniform -results. With the exercise of care, there is little reason for the -mordanting operations to go wrong. - -After proper treatment of the skins in the mordants, they are removed and -drained off, then rinsed lightly in running water to remove the excess -of mordant liquor, after which they can be directly entered into the -dye bath. If it is not feasible to dye the mordanted skins at once, as -is often the case, the skins are kept moist, and under no circumstances -allowed to dry. - - - - -CHAPTER XII - -FUR DYEING - -MINERAL COLORS USED ON FURS - - -Before the introduction of the fur dyes now used, certain inorganic -chemical substances were employed in addition to the vegetable dyes, -for the production of colors on furs. Even to this day such materials -are used to obtain certain effects in special instances. The idea of -employing mineral chemicals undoubtedly originated in the textile-dyeing -industry, which at one time was dependent to an appreciable extent on -mineral substances for the production of certain fast shades. Compounds -of iron, lead, manganese, also of copper, cobalt and nickel were all used -for dyeing, either singly or in various combinations. In the application -on furs, the brush method was the only one practicable, as the skins would -have been ruined by dipping them into solutions of these chemicals in the -concentrations necessary for dyeing. - -The dyeing of furs with mineral colors involves the precipitation on -the fibre in a more or less permanent form of the sulphide, oxide or -other insoluble compound of a metal, and can be brought about in several -ways. By what is known as double decomposition, that is, by the use -of two solutions successively applied, the ingredient of one causing a -precipitate to form when in contact with the constituent of the second, -the color is produced on the hair. Another method is to use solutions of -chemicals which decompose on contact with the hair, forming an insoluble -compound. In the first method the hair is alternately treated with the -two solutions of the requisite chemicals, drying between each brushing, -the process being repeated until the desired shade is obtained. The second -method merely requires the solution of the chemical to be applied to the -hair, which is then dried, the color forming by itself. - -One of the most important of the mineral dyes, and which is occasionally -used to this day, is lead sulphide, formed by the double decomposition -method by precipitating a soluble lead salt with ammonium sulphide, or any -other alkaline sulphide. By simply brushing an aqueous solution of lead -acetate, also known as sugar of lead, on a white fur such as white hare or -rabbit, a light, brownish coloration is obtained due to the combination of -the lead with the sulphur of the hair. If the lead solution is carefully -applied several times on this type of fur, until a sufficiently dark -color is produced, it is possible to get a fairly good imitation of the -stone marten. The brown color is very fast, being actually formed within -the hair. In most cases, however, for dyeing lead sulphide shades it is -necessary to use the two solutions. Thus the pale greyish or slightly -brownish-grey shades of the lynx can be reproduced on white rabbit or -hare by this process. A solution containing 60 grams of lead acetate per -liter of water is brushed on to the hair of the fur which has previously -been killed in the usual manner, and the hair is then dried. A solution -of 50 grams of ammonium sulphide per liter of water is next brushed on, -and the fur again dried. Care must be exercised in handling the ammonium -sulphide as it is a very malodorous liquid, the fumes of which are -poisonous when inhaled. The alternate brushings are repeated until the -desired depth of shade is obtained. A very dark brown, approaching a black -can be obtained in this way. This color can be used for the production of -certain attractive effects. By brushing over the tips of the hair, which -has previously been dyed a dark brown by means of the lead sulphide color, -with a dilute solution of hydrochloric acid, or with peroxide of hydrogen, -the hair will become white in the parts so treated, due to the formation -of lead chloride or lead sulphate, respectively. Thus white tipped furs -can be obtained, but the process is applicable only when the furs have -been dyed by the lead sulphide method. - -Potassium permanganate is occasionally used to produce dyeings of a -brown shade on furs. Considerable care has to be taken in applying this -substance, as it is possible to affect the hair. The strength of the -solution must be varied according as the hair to be dyed is weak or -strong. A cold solution of 10 to 20 grams of potassium permanganate per -liter of water is brushed on to the hair, which is then dried. A brown -precipitate of manganese is formed on the hair after a short time, and -the process is repeated until the required shade is obtained. For furs -with harder hair, stronger solutions can be used. The dyeing is very -fast, but it is seldom used, cheaper and better shades being obtained in -other ways. Spotted white effects can be produced on the brown dyeing with -permanganate of potash by applying a solution of sodium bisulphite, the -brown color being dissolved by this chemical. - -The compounds of other metals, such as iron, copper, cobalt and nickel -are not used in practise as the dyeings are not fast, and can be better -produced in other ways. - - - - -CHAPTER XIII - -FUR DYEING - -VEGETABLE DYES - - -With the exception of the few shades which could be produced solely by -means of coloring matters of a chemical character, all dyeings on furs up -to about thirty years ago were made with dye substances obtained from the -vegetable kingdom, either alone, or in conjunction with the aforementioned -mineral colors. The colors of vegetable origin used in comparatively -recent times were mainly extracts of the wood of certain trees; so the -name "wood dyes" has come to be applied generally to the dyes of this -class. The use of the vegetable or natural dyes on furs dates back to -quite ancient times, as frequent allusions and descriptions in Biblical -and other contemporaneous literature testify. There are numerous pictures -on monuments and tablets illustrating the dyeing of furs among the ancient -Egyptians, the evidence indicating that the juice of certain berries, and -extracts of certain leaves were used for the purpose. At a later period, -in the Roman era, henna, which was used over two thousand years ago as -to-day for the beautification of the hair of women, was also used to -color fur skins. The instances cited here are merely of scientific and -historical interest, and are not of practical importance as far as fur -dyeing methods are concerned. - -It was not until many centuries later that the dyeing of furs took on -the aspects of a commercial art, and the substances then employed were -chiefly tannin-containing materials such as gall-nuts and sumach, which -in conjunction with certain metallic salts, particularly those of iron, -were capable of producing dark shades. The use of iron compounds to form -dark grey or black colors on leather tanned by means of the tannins, had -been common for a long time, and it was natural that fur dyers should -try to produce such shades on furs in a similar fashion. The use of the -iron-tannin compound as a dye proved to be very effective, and to this day -the production of blacks by means of the vegetable coloring matters has as -a basis an iron-tannate. A formula in common use in the latter seventeenth -and the eighteenth centuries for producing black shades on furs, is the -following: - - Lime water 1117 parts - Gall-nuts 1500 " - Litharge 500 " - Salammoniac 65 " - Alum 128 " - Verdigris 64 " - Antimony 64 " - Minium 32 " - Iron filings 128 " - Green copperas 384 " - -All these substances except the gall-nuts, the copperas and half the lime -water were boiled up in a cauldron; then the gall-nuts and the copperas -were placed in a bucket and the contents of the cauldron poured in, and -the rest of the lime water added. The mixture was stirred up, allowed to -settle for an hour, and when cool, was ready to be applied by the brush -method. For dyeing by the dip process, a similar mixture was used, only -considerably diluted with water. A study of the formula discloses the -fact that in it are combined killing and mordanting substances as well -as dyeing materials. The lime water, in conjunction with the salammoniac -serves as a killing agent, the verdigris, copperas and alum are mordants, -while the litharge and the minium, both compounds of lead, could possibly -act as mineral dyes, and the iron filings and the antimony took virtually -no part at all in the dyeing, except, perhaps to act in a mechanical way. - -The formulas for other shades were made up along similar lines, the chief -constituent of vegetable nature being either gall-nuts, sumach, or both. -A mixture for a chestnut brown, for example, contained gall-nuts, sumach, -and the various other mineral constituents as in the black dye, litharge, -alum, copperas, verdigris, salammoniac, antimony, and in addition, red -lead and white lead. It is evident in both these instances that the shade -obtained was as much the result of mineral dyeing as of vegetable dyeing. - -The discovery of America introduced into Europe many new dye substances, -chiefly wood extracts such as logwood and Brazilwood, but it was not until -the nineteenth century that these materials found their way into the -dye formulas of the fur dyer. Most of the processes used in the dyeing -of furs were adaptations of methods employed in silk dyeing, the silk -fibre being considered as most nearly approaching fur-hair in nature and -characteristics. By devious and circuitous paths the formulas of the silk -dyers reached the fur people, and so, in the middle of the nineteenth -century, dye mixtures containing the various dyewoods as well as the -tannin-containing substances were in general use for the dyeing of furs. -The following is a typical recipe of that time for the production of black -on furs like wolf, skunk, raccoon, etc.: - - Roasted gall-nuts 1000 parts - Sumach 200 " - Iron mordant 200 " - Copper vitriol 100 " - Litharge 80 " - Alum 60 " - Salammoniac 50 " - Crystallized verdigris 40 " - French logwood extract 30 " - Rain water 7000 " - -The mixture was boiled up, and after cooling was ready for application by -the brush method, the skins being first killed by a killing mixture also -applied by the brush. The dye substances in this case are the gall-nuts, -sumach and the logwood extract, with the iron mordant, copper vitriol, and -alum as mordants. For brown shades a similar formula was used containing -Pernambuco wood extract, logwood extract, quercitron bark, gall-nuts and -dragonblood, together with iron, copper and alum mordants. - -Formulas such as the above were mainly empirical, that is, they -were compounded as a result of trial of various combinations of the -constituents, without considering the nature and quantitative character -of the reactions, as long as the desired shades could be obtained. Such -dye mixtures were frequently found to yield results varying from those -expected or originally obtained, because the effectiveness of the formulas -depended upon the exact duplication in every detail, of conditions which -had given satisfactory results previously, and it was not always possible -to attain such an accurate reproduction of circumstances, especially -when the fur dyers were quite ignorant of the scientific relationships -of the materials used. So when more light had been shed on the nature -and chemical characteristics of the vegetable dye substances, formulas -like those described were no longer employed, although the essential -ingredients were the same in the new processes. Unnecessary constituents -were eliminated, and proper ones substituted where it was required, and -the quantities of the materials used were made to conform to the chemical -laws governing the reactions. Since these new formulas were based on a -rational understanding of the constituents and their reactions, it is -desirable to study the latter briefly, before further discussing the -formulas themselves. - -The substances of vegetable origin used in modern fur dyeing may be -grouped into two classes, one, the tannin-containing materials, and -the other, the dyewoods proper. The most important of the tannins are -gall-nuts, sumach and chestnut extract. Cutch, which also comes under -this class, is more frequently used for the production of brown shades, -so it is grouped with the dyewoods. Among the latter are logwood, fustic, -Brazilwood, quercitron, turmeric, and several others of less significance. - - -1. _Tannin Materials_ - -First and foremost under this heading are the nutgalls. These are -ball-shaped excrescences produced on certain plants by the punctures -of insects in depositing their eggs. There are two chief varieties, the -European, and the Chinese. The European galls are formed by the female -gall-wasp which drops an egg in the rind of young branches of certain -oaks. A swelling (the nutgall) is produced, in which the young insect -develops, and from which it finally escapes by piercing a hole through -the shell. Those galls which are not pierced have a fresh bluish or green -color, are heavy and contain most tannic acid. After the insect has gone -out, the galls are of a lighter, yellowish color, and also of inferior -quality. The best oak-galls are the Aleppo, and the Turkish or Levant -galls, containing 55-60% of tannic acid, and about 4% of gallic acid. The -Chinese galls are produced by the puncture of a plant-louse on the leaves -and leaf-stalks of a species of sumach, and not on oaks. The galls are -very light, and very rich in tannic acid, containing often as much as 80%. -For dyeing purposes, nutgalls are usually ground to a powder, and in some -instances they are even roasted first and then ground. - -Sumach consists of the leaves and sometimes of the small twigs and stems -of a species of sumach plant known as the Rhus coriaria. The Sicilian -variety is the finest commercial quality, with the Virginian ranking next. -It is sold as a powder, but also in the form of the whole or crushed -leaves. The best sumach contains 15-25% of tannin. Extracts are also -manufactured, a liquid extract of 52 degrees Twaddell, which forms a dark -brown, thick paste; and a solid extract, formed by evaporating the liquid -extract to dryness. - -Chestnut extract is prepared from the wood of the chestnut oak, which -contains 8-10% of tannin. The solid extract has a bright, black color, -while the liquid extract is a dark brown paste with a smell like that of -burnt sugar. - -The tannins all give greyish to black shades with iron salts, and it is -this fact which renders them important for fur dyeing. - - -2. _Wood dyes_ - -One of the most important of all the natural dye substances, especially -for the production of blacks, is logwood. The color is really a red, but -with the common mordants it forms blue, violet or black shades. Logwood, -or campeachy wood, as it is sometimes called, is the product of a large -tree growing in the West Indies, and Central and South America. When -freshly cut, the wood is practically without color, but when exposed to -the air it soon becomes a dark reddish-brown on the surface. The coloring -principle of logwood is called hematoxylin, which is a colorless substance -when pure, and is of itself incapable of dyeing; but when it is exposed -to the air, especially when moist and in the presence of some alkaline -substance, it is converted into hematein, which is the real coloring -matter of logwood. To prepare the wood for use, the logs are chipped or -rasped, the chips being heaped up and moistened with water. Fermentation -occurs, and the heaps are frequently turned to allow free access of air to -the wood, and to prevent overheating. As a result of this process, a great -part of the hematoxylin is converted to the hematein. The logwood may -be used for dyeing in this state as chips, but logwood extracts can now -be obtained of a high degree of purity and are easier to work with. The -commercial forms of the extract, are the liquid of 51 degrees Twaddell, -and the solid extract. Hematein crystals can also be obtained. All these -extracts contain mainly hematein, together with a small percentage of -hematoxylin which is converted to the former during the dyeing process. -Logwood is never used as a direct dye, but is used to form color lakes -with the various mordants, the following colors being produced: - - Iron mordants give grey to black shades - Copper mordants give green-blue to black shades - Chrome mordants give blue to black shades - Aluminum mordants give violet shades - Tin mordants give purple shades - -By combining several of the mordants, any desired shade of black can be -obtained, and if other dyewoods are used in conjunction with the logwood, -the range can be further increased. - -Fustic, yellow-wood, or Cuba wood, as it is variously called, is obtained -from a tree also growing in the West Indies, Central and South America. -It is used either as wood chips, or as a paste extract of 51 degrees -Twaddell, and occasionally as solid extract. Fustic contains two coloring -matters, morintannic acid, possessing the characteristics of a tannin, and -which is quite soluble in water, and morin, which is rather insoluble, and -which settles out from the liquid extract. Fustic is the most important of -the yellow dyes of natural origin, and is used considerably in fur dyeing -with logwood for shading the blacks, or for producing compound shades. -With the usual mordants fustic gives the following colors: - - With iron salts dark olive - With copper salts olive - With chrome salts olive-yellow to brownish-yellow - With aluminum salts yellow - With tin salts bright yellow to orange-yellow - -Brazilwood, or redwood, is the product of a tree found in Brazil, and -exists in several varieties, such as peach wood, Sapan wood, Lima wood, -and Pernambuco wood. They all yield similar shades with the various -mordants, and all seem to contain the same coloring principle, brasilin, -which, like the hematoxylin, has no dyeing power, but by fermentation and -oxidation it is converted to brasilein, corresponding to the formation -of hematein. Brazilwood and the related woods are used either as chips or -extract, but seldom alone, usually in conjunction with other dyewoods. By -combining logwood, fustic and Brazilwood in various proportions, and by -employing suitable mordants, all the shades required by the fur dyer can -easily be produced. - -Quercitron is the inner bark of a species of oak (Quercus tinctoria) found -in the United States. It contains two coloring principles, quercetrin and -quercetin. The fresh decoction of quercitron bark is a transparent dull -orange-red which soon becomes turbid and deposits a yellow crystalline -mass. It is generally used in conjunction with other dyes. - -Cutch is the dried extract obtained from a species of acacia, the -principal varieties being Bombay, Bengal, and Gambier cutch. It contains -two coloring principles, catechin and catechu-tannic acid. Cutch acts as -a tannin, and like other tannins discussed above, can be used for the -production of grey or black shades with iron mordants. It is employed -chiefly, however, for dyeing browns. Aluminum salts give with cutch -a yellowish-brown, tin salts give a lighter yellow, copperas gives a -brownish-grey, and chrome and copper salts give brown shades. - -Turmeric is the underground stem of the Curcuma tinctoria, the coloring -principle being called curcumin. It may be used as a direct dye, but -usually a mordant is used. Turmeric is sometimes used in place of fustic. - -While the tannins can be used alone with an iron mordant for producing -greyish to black shades, the dyewoods alone yield colors which would be -too bright to be suitable for dyeing furs. In order to tone down this -brightness, and to give to the dyeings that greyish undertone which is -characteristic of the natural furs, and which can only be imitated by -means of the iron-tannin compound, it is customary to combine the tannins -with the wood dyes. The iron-tannate constitutes the foundation of the -color which gets its intensity, and necessary brilliancy and bloom from -the wood dyes. Moreover, the presence of the iron-tannin compound helps -considerably to increase the fastness of the dyeing. Furs dyed with the -combination of the tannins and the wood dyes obtain an additional tanning -treatment which materially improves the quality of the leather, for not -only do the tannin substances exert this tanning action, but the dyewoods -as well, for they are themselves either of the nature of tannins, or -contain a coloring principle which is a tannin. It is to the combined -effects of the tannin substances and the dyewoods that furs dyed with -vegetable dyes owe their beauty of color, lustre, naturalness of shade, -permanence of the dyeing, and durability of the leather. Wood dyeings -on furs have for this reason acquired a just renown, but owing to the -introduction of the new kinds of fur dyes, the use of the vegetable dye -substances has been greatly reduced. - -The dyes of vegetable origin can be applied to furs by either the brush -method or the dip method, or both, and since mordants are required -with the dyes of this class, they are applied in one of the three ways -mentioned in a previous chapter: first, by mordanting before dyeing; -second, by applying mordant and dye simultaneously; and third, by -mordanting after the skins have been treated with the dye. - - -I. DYEING WITH VEGETABLE DYES BY THE BRUSH METHOD - -The use of the brush method in applying the natural dyes to furs is -limited to a comparatively few kinds of dyeing, namely to produce -special effects on furs, or to give to the upper-hair of furs a coat -of dye different from the base color. In a quite recent German patent -is described a process for blending a red fox as a silver fox and -the procedure affords a good example of brush dyeing with preliminary -mordanting. The specification is as follows: "D. R. P. 310, 425 (1918). -A process for dyeing red fox as silver fox. The tanned and dressed skin -is first superficially decolorized by applying a dilute mixture of milk -of lime, iron vitriol and alum, with a soft brush so as only to penetrate -the top-hair. Allow to remain for 4-6 hours, dry, and beat out the dust. -A dilute solution of iron vitriol is brushed on so as only to wet the -top-hair, and the skin is thus allowed to remain moist for 12-24 hours. -Then without drying, a solution of iron vitriol, salammoniac, litharge, -red argol and wood ashes is brushed on cold with a hard brush so as -to penetrate all the hair down to very near the skin. The skin has now -completely lost its red color, and has become a pale yellow. It is now -ready to be dyed. An infusion of roasted nutgalls, which have been boiled -for 3-4 hours with water, is applied cold with a soft brush to the upper -hair. Allow to remain so for 2-3 hours, and without drying, apply a weaker -solution of the roasted nutgalls with a hard brush so as to saturate the -hair thoroughly. Dry and beat out. According to the concentration of the -solution applied, the hair will be colored blue-grey to black, and the -shade can be varied by varying the strength of the solutions used. The -different parts of the skin, or those parts of different shades can be -dyed accordingly." - -In this patent all the operations, including killing, mordanting and -dyeing are done by the brush method, and the process, from this point -of view is quite similar to one which might have been employed a century -previous. It is evident that the time and effort required to carry out the -details as described in the patent would only be warranted in exceptional -cases, where the value of the dyed fur would be considerably greater than -that of the natural skin. - -An example of the application at the same time of dye and mordant by the -brush method is the original French Seal dye, which is still employed to -a limited extent to produce a brilliant, deep, lustrous black topping on -furs which have already been dyed by the dip process. A typical formula -for the old French Seal dye is the following: - - Green copperas 10 parts - Alum 10 " - Verdigris 10 " - Gall-nuts 80 " - Logwood extract - (15 degrees Twaddell) 150 " - Water 1000 " - -This mixture is applied to the top of the hair of the furs, after previous -killing, and the skins allowed to remain moist for several hours, and -also exposed to the air. The skins are then dried, and beaten out, and if -necessary a second coat of dye is brushed on. In dyeing seal-imitation -on muskrat, or skunk-imitation on opossum, for example, the black color -required on the top-hair, or the upper part of the hair when the furs are -sheared, can be produced by applying a mixture similar to the above, to -the furs after they have received their base color by the dip process with -natural dyes or with the Oxidation Colors. Occasionally, the dyeing is -given an after-treatment with a dilute solution of sodium bichromate to -help develop the color, the action in this case being that of an oxidizing -agent, and not of a mordant. - -As far as the third method of mordanting is concerned, that of first -applying the dye, and then the mordant, it is rarely practised with -the brush method. The procedure, however, consists in first brushing -on a solution of the desired dye, then drying and brushing on a mordant -solution. These operations are repeated perhaps two or three times until -the proper shade is obtained, exposing the furs to the air for the color -to be developed. - - -II. DYEING WITH VEGETABLE DYES BY THE DIP METHOD - -It was in the application to furs by the dip process that the use of the -vegetable dyes attained great importance, and although at the present -time, natural organic dyes have largely been superseded by the Oxidation -Colors and Aniline Black dyes, yet for certain purposes, and especially -for the production of blacks, the wood dyes still are able to hold their -own. - -The dyeing of black formerly constituted probably the most important -branch of the fur dyeing industry, and was undoubtedly the most difficult -one. For it is possible to obtain as many different kinds of black -as there are dyers of this color, but only a few certain shades are -desirable. The division of the classes of furs into those derived from -the various kinds of sheep, and those obtained from other animals is -particularly marked in the dyeing of black, and both the composition of -the dye formulas and the methods of dyeing are somewhat different for -the two groups. For the dyeing of black on Persian lambs, broadtails, -caraculs, etc., a combination of logwood and nutgalls with the requisite -mordants is used, while on hares, Chinese sheep, foxes, raccoons, opossum, -etc., a mixture of logwood and turmeric or fustic, with the proper -mordants is used. - -The general procedure is as follows: The dye substances to be used are -ground up to a powder in a mill constructed for the purpose, after which -they are boiled with water in a copper-lined kettle or cauldron, heated -from the outside by steam. The customary arrangement is to have a jacketed -kettle, supported on a stand, and having taps and valves to enable the -liquor to be drawn off, or pivoted, so that the kettle can be tilted, -and the contents poured out. The use of the copper-lined vessel is to be -preferred, as it is unaffected by any of the dye substances, and so cannot -cause any rust stains. After the dyes have gone into solution and have -cooled, the mordant chemicals, previously dissolved in water, are added, -and the mixture stirred up. The dyeing in this instance is effected by the -simultaneous application of dye and mordant. The dye mixture is now run -off, or poured out in the proper quantity into a number of small vats of -25-30 gallon capacity, or into a paddle vat, which can be closed, while -the paddle is rotating. The latter device is to be preferred because it -permits the dye to retain its temperature better and for a longer period -of time, but when lambs are being dyed only the open vats are used. The -temperature of the dye mixture is between 40° and 45° C., for only at -this temperature can the hair absorb the dye properly without injuring the -leather. The killed skins are immersed in the dyebath for a time, usually -overnight, after which they are removed, drained and hung up, with the -hair-side exposed to the air, so as to permit the dye to develop, which -takes place with the aid of the atmospheric oxygen. The dyebath is again -brought to the proper temperature, and the skins are again entered, to go -through the same process as often as is necessary to obtain the desired -depth of shade. The dyed skins are thoroughly washed to remove excess dye, -then dried and finished. The following are a few dye formulas used in the -production of blacks: - - Logwood extract 100 grams - Chestnut extract 14 c.c. - Turmeric 38 grams - Iron acetate 6° Bé. 50 c.c. - Water 1200 c.c. - -or, - - Cutch 15 grams - Soda 14 grams - Logwood extract 120 grams - Verdigris 19 grams - Iron acetate 5° Bé. 16 c.c. - Water 1200 c.c. - -A recently published formula for dyeing China goat skins black, is the -following: - -Dissolve 50 lbs. of dark turmeric and 45 lbs. of logwood extract and -make up to 300 gallons of solution, at 95° F. Enter the killed skins and -leave them in the liquor until they rise to the surface. Then take them -out and add 25 lbs. of logwood extract, 10 lbs. of sumach, 10 lbs. of -blue vitriol, 5 lbs. of fustic extract, and about 60 lbs. of iron acetate -liquor. Stir up well, and immerse the skins for 18 hours. Draw them up, -and expose to the air for 12 hours. Heat the liquor again to 95° F. and -put the skins back for 12 hours. Draw out, hang up in the air for a time, -then wash thoroughly, hydro-extract, dry and finish. - -In a German patent, D. R. P. 107,717 (1898), is described a method for -dyeing lambs black, consisting in treating the skins for 24 hours in a -logwood bath, then rinsing in cold water, and mordanting for 15 hours in -a solution of bichromate of potash. The skins are then washed and treated -with a solution of iron salt, then dried. This process, while of not much -practical importance, is an illustration of mordanting subsequent to the -dyeing treatment. - -As far as the production of other shades is concerned, the procedure is -quite similar to the regular black method. For a dark brown, for example, -the skins are dyed in a mixture containing - - Gall-nuts 40 parts - Verdigris 10 " - Alum 10 " - Copperas 5 " - Brazilwood extract - (15° Twaddell) 150 " - Water 1000 " - -employing operations just as in the case of the black. - -Greyish-blue shades on white hares, lambs, kids, etc., can be obtained by -treating the skins successively in the following baths: - - 1. Logwood extract 100 grams - Water 1 liter - 2. Indigotine 10 grams - Alum 10 grams - Water 1 liter - -Bluish-grey tones on the same furs can be produced by treating with - - 1. Logwood extract 200 grams - Indigotine 15 grams - Water 1 liter - 2. Alum 150 grams - Salammoniac 12 grams - Water 1 liter - -Similar grey shades can be produced by mordanting the skins with an iron -salt, and then dyeing in a weak bath containing gall-nuts, sumach and iron -vitriol. This method is very effective for making Alaska or silver fox -imitations. - - - - -CHAPTER XIV - -FUR DYEING - -ANILINE BLACK - - -Fur seal for a long time has been a fur of distinction and importance in -the fur industry, and consequently the dyeing of seal has constituted an -important, though not very extensive branch of the art of fur dyeing. -In quite recent times the popularity of seal has become so great that -imitations have had to be produced to help supply the demand, and as a -result, French seal, or seal-dyed rabbit, and the so-called Hudson seal, -which is seal-dyed muskrat, have acquired a great vogue. Occasionally -opossum, nutria and other furs are also used for the purpose of producing -seal imitations. While the supply of real seals is relatively small, and -the demand large, the production of seal imitations has assumed large -proportions, and as a result, the dyeing of seal and its imitations or -substitutes has come to be a great branch of the fur dyeing industry. - -During the past thirty years, the long and tedious processes of dyeing -seal and seal imitations, involving the use of dyes of vegetable origin, -have largely been superseded by what is known as the Aniline Black dye. -It was the French who first worked out successfully the application of -Aniline Black to furs, and the method has attained much importance and -extensive use in the fur dyeing industry. - -Aniline Black is the name given to an insoluble black dyestuff produced -by the oxidation of aniline in an acid medium. As a finished product it -cannot be used in fur dyeing, but if the hair of the furs be impregnated -with a suitable preparation of aniline and then treated with certain -oxidizing agents, the color will be formed on the hair, being firmly -fixed and giving a fast black, resistant to light, washing and rubbing. -The basis of the dye, aniline, is an oily liquid, possessing a peculiar -fishy odor, colorless when pure, but rapidly turning brown when exposed to -the air. It is obtained from benzol, which is distilled from coal-tar, by -treating with nitric acid, forming nitrobenzol, which when subjected to -the action of reducing chemicals is converted into aniline. The process -may be shown schematically as follows: - -Coal--coal-tar--benzol--nitrobenzol--aniline oil--Aniline Black. Aniline -Black was by no means a new dye when the French succeeded in producing it -on furs. It had been used for a long time previous on textiles, chiefly -cotton. The history of the development of the Aniline Black process -throws considerable light on its nature and constitution, and so presents -many features of interest. As early as 1834, the chemist Runge observed -the formation of a dark green color when heated aniline nitrate in the -presence of cupric chloride. Fritsche, in 1840, noticed that when chromic -acid was added to solutions of aniline salt, a dark green, and sometimes a -blue-black precipitate was produced, and later the same chemist obtained -a deep blue by the action of potassium chlorate on aniline salt. It is -interesting to note that Perkin, in 1856, conducting similar experiments -on the oxidation of aniline with chromic acid, obtained a blue-black -product from which he extracted the first synthetic coal-tar dye, mauve. -Thus far, all the experiments on the oxidation of aniline proved to be -merely of scientific interest, but in 1862, Lightfoot patented a process -for the practical application of colors formed by the oxidation of aniline -on the fibre, a greenish shade being obtained by that method, to which the -name emeraldine was given, and by subsequent treatment with bichromate -of potash, the green was changed to a deep blue color. Since that time, -the methods for producing and applying Aniline Black have been developed -and improved, although all the processes were based on the principles -incorporated in Lightfoot's original patent. However, it was not until the -last decade of the nineteenth century that the dyeing of furs by means of -the Aniline Black method was successfully attempted. - -A knowledge of the nature and the manner of the chemical changes which -take place in the production of Aniline Black is a valuable aid in -obtaining satisfactory results in practise; and although Aniline Black -was extensively used before the true character of the reaction was -understood, since the successful determination of the constitution of -Aniline Black and the discovery of the real nature of the process by -Green and his collaborators in 1913, the methods have been considerably -improved and simplified, with correspondingly better results in dyeing. -As a consequence, the methods of dyeing furs with Aniline Black have also -become simpler and more efficient. - -A discussion of the chemical changes which occur in the Aniline Black -process, is out of place here on account of the highly involved and -complicated character of the reactions, to understand which requires a -considerable knowledge of specialized organic chemistry. But the essential -features of practical importance in the production of Aniline Black are -the following: As already noted, one of the characteristic properties of -aniline is its tendency to turn from a colorless to a dark-brown liquid in -the presence of the air. This change is due, together with certain other -causes, to an oxidation brought about by atmospheric oxygen. By employing -oxidizing agents, this oxidation can be accelerated and carried further, -and eventually the Aniline Black is obtained. Among the substances which -may be used to bring about the conversion of aniline to the insoluble -black dye are manganese dioxide, lead peroxide, hydrogen peroxide, chromic -acid, ferric salts, potassium permanganate, chloric acid and chlorates -in the presence of certain metallic salts, particularly those of vanadium -and copper. Chlorates, especially sodium chlorate and potassium chlorate, -are the most commonly employed oxidizing agents, bichromate of soda or -of potash being used, in addition, to complete the oxidation. When using -chlorates it is necessary to have present in the dye mixture a small -quantity of a metallic salt, which, while not entering into the reaction -itself, is nevertheless indispensable as an oxygen carrier. Vanadium -compounds have proved to be the most effective for this purpose, and -according to an authority, one part of vanadium salt is sufficient to -cause the conversion of 270,000 parts of aniline to Aniline Black, the -necessary amount of a chlorate being present of course. Salts of copper, -cerium, and iron are also extensively used, but they are not quite so -efficient as vanadium. - -The formation of the Aniline Black in practise takes place in three -well-defined steps, which it is important to be able to recognize and -distinguish in order to obtain the best results. The first stage of the -oxidizing process produces what is called emeraldine, which in the acid -medium of the aniline bath is of a dark green, while in the free state it -is of a blue color. As the oxidation proceeds, the second stage develops, -the emeraldine being converted to a compound called nigraniline. This in -acid solution is blue, and the free base is a dark-blue, almost black. -It was formerly considered that the nigraniline was the Aniline Black -proper, and so when this stage of the oxidation was reached, the process -was often interrupted and not carried to the limit. This can account for -the fact that Aniline Black dyeings usually turned green after a short -time. The reason for this is that nigraniline, when treated with weak -reducing agents, as, for example, sulphurous acid, is at once changed -to emeraldine, with its dark green color. Since there is usually a small -amount of sulphurous acid in the air, especially in places where coal or -gas is burned, an Aniline Black dyeing which has not been carried beyond -the nigraniline stage will be reduced in time to the emeraldine, and cause -the dyeing to become green. The last step in the oxidation changes the -nigraniline into what is properly called the ungreenable Aniline Black. -Weak reducing substances like sulphurous acid do not change this compound -to emeraldine, and stronger reducing agents only convert it to a brownish -compound, which changes back to the black when exposed to the air. It is -quite evident that in order to obtain a black which will not change to -green in time, the oxidation of the aniline must be carried to the last -stage. By making tests during the dyeing of the furs, it can easily be -determined whether the oxidation has proceeded far enough. - -In the dyeing of textiles with Aniline Black, it is customary to carry -out the operation at comparatively high temperatures, approaching 100° -centigrade. With furs such temperatures are out of the question, so it is -necessary to repeat the dyeing several times in order to obtain the proper -depth of shade working in the cold. Only the brush method can be used in -applying the Aniline Black dye to furs, on account of the strong acidity -of the dye mixture, which would ruin the leather, if the dyeing were done -in a bath. Indeed, great care must be exercised even by the brush method -to avoid too great penetration of the dye liquid, otherwise the roots -of the hair will be attacked, and the leather may be "burned" from the -hair side. Furs dyed with Aniline Black are frequently after-dyed by the -dip-process with logwood or some other similar dye, in order to add to -the brilliancy of the dyeing. Combined with intensity of color, Aniline -Black on furs is the only dye which will also give fast, lustrous shades, -and leave the hair soft and smooth. - -There are several methods of applying Aniline Black on furs, the most -important being - - 1. One-bath Aniline Black - 2. Oxidation Aniline Black - 3. Diphenyl Black - 4. Aniline Black by Green's Process - - -1. _One-bath Aniline Black_ - -A typical formula for this method is the following given by Beltzer: - - Aniline salt 10 kg. - Sodium chlorate 1.5 kg. - Copper sulphate 0.7 kg. - Vanadate of ammonia 10 gr. - -All these substances are dissolved hot in 50 liters of water, and allowed -to cool, forming solution A. Aniline salt is aniline oil which has been -neutralized with the exact quantity of hydrochloric acid to form the -hydrochloride. It forms white or greyish crystalline lumps very easily -soluble in water. The sodium chlorate is the oxidizing agent, and the -copper sulphate and the vanadate of ammonia are the oxygen carriers. - -15 kg. of sodium bichromate are also dissolved in 50 liters of water, -forming solution B. The bichromate is also an oxidizing agent and serves -to complete the oxidation of the aniline to the black. - -Immediately before using, solutions A and B are mixed together, both being -cool. In general practise it is customary to mix only small quantities -at a time, as a considerable precipitate forms when the whole batch -is mixed at once, the precipitate being so much waste dye substance. -Usually a liter of A and a liter of B are mixed at a time, and the furs -brushed with the mixture. The brushing must be varied according as the -hair is hard and stiff, or soft and tender. The hair must be thoroughly -impregnated in all directions, and the penetration must not be too deep -to affect the leather. With experience and dexterity satisfactory results -can easily be achieved. After the skins have been properly treated, they -are dried at a temperature of about 35 degrees centigrade. When dry, they -are returned to the dye bench, where they receive another application -of the dye mixture, and are again dried. This operation may be repeated -as often as six or seven times before a sufficiently intense black is -obtained. Another way of producing the desired depth of shade with fewer -applications is by using more concentrated dye mixtures. Each method -has its disadvantages, the greater number of brushings requiring the -expenditure of more time and labor, and the greater concentration of -the bath resulting in a considerable loss of dye substance due to the -formation of a large precipitate when the two solutions are mixed, and -moreover, not all furs can be treated with concentrated mixtures. The best -results with this method usually require the application of six coats of -a mixture of moderate concentration. - - -2. _Oxidation Aniline Black_ - -In order to overcome the difficulty of employing very concentrated dye -mixtures, or of making many applications of the dye, a method was devised -whereby the two solutions of the previous process, instead of being mixed -together, are applied successively to the hair of the furs, the following -formula, also by Beltzer, being an example: - - Aniline oil 10 liters - Nitric acid 36° Beaumé, or - Hydrochloric acid 22° Beaumé 20 liters - Cold water 20 liters - -This is solution A, and is merely a solution of aniline hydrochloride, -or nitrate, depending on which acid has been used. Nitric acid, although -more costly than the hydrochloric acid, is to be preferred, because it -is an oxidizing acid, and so assists in the oxidation of the aniline, and -besides, has a more beneficial effect on the hair than the hydrochloric, -in the matter of softness and luster. - - Sodium chlorate 4 kg. - Copper sulphate 1 kg. - Vanadate of ammonia 10 gr. - Water 50 liters - -This is solution B, containing the oxidizing agent, and the oxygen -carriers. Just before using, equal quantities of A and B are mixed, and -the skins brushed with the mixture. The skins are then dried at 35-45° -centigrade, at which temperature the color begins to develop. When almost, -but not entirely dried, the skins are subjected to the action of warm -vapor, which is allowed to enter the drying chamber, so as to keep the -temperature about 40° centigrade, the color developing better in this -way. This operation may be repeated, or the skins are directly treated -with a solution of 25 kg. of sodium bichromate in 100 liters of water, -to complete the oxidation. The moist skins are exposed to the air for a -time, and then dried at 35° C. - -This method of dyeing has several advantages over the One-bath Aniline -Black. It requires fewer brushings, and enables the complete utilization -of the dye solutions without loss. With three applications of the dye -mixture by the Oxidation process, as deep and intense a black can be -obtained as with six brushings by the One-bath method. The dyeings, too, -are nearly, but not fully as brilliant and even as in the latter case. -The greater the number of coats of dye that are applied the more regular -will the dyeing be. - - -3. _Diphenyl Black_ - -In 1902, the Farbwerke Hoechst, a large German producer of coal tar -intermediates and dyes, invented an Aniline Black process to which they -gave the name Diphenyl Black. The chief departure from the previous -Aniline Black methods was the replacing of part of the aniline oil of the -dye mixture by Diphenyl Black Base I, which is para-aminodiphenylamine. -This base has the property of being oxidized to Aniline Black, just like -aniline oil, and the advantage claimed for the Diphenyl Black is that it -produces an absolutely ungreenable black. The method of application is -practically the same as for the other Aniline Black processes, chlorates -being used as the oxidizing agents, in the presence of oxygen carriers -such as salts of copper and vanadium. The use of bichromates is dispensed -with. On account of the comparatively high cost of the Diphenyl Black -Base I, this method has not found very extensive application, especially -as highly satisfactory ungreenable blacks can now be produced by other -methods. - - -4. _Aniline Black by Green's Process_ - -In 1907, Green, who has done much work in the direction of elucidating the -character of the Aniline Black process, obtained a patent for a method -of applying Aniline Black in a manner which was different from all the -previously known formulas. The invention created great interest, and -although in its original form it did not find a wide application, many of -the methods used at the present time are in one way or another derived -from the idea of Green. A resumé of the patent will therefore be given -here: "The invention relates to the production of an Aniline Black, the -new process differing from all other known processes by the fact that -the oxidation of aniline is effected solely or mainly by the oxygen of -air. The possibility of dispensing with an oxidizing agent depends on the -discovery that the addition of a small quantity of a para-diamine, or of -a para-amido-phenol to a mixture containing aniline and a suitable oxygen -carrier, such as a salt of copper, greatly accelerates the oxidation of -the aniline by the atmospheric oxygen. Further, whereas in the ordinary -processes of Aniline Black, the quantity of mineral acid employed cannot -be materially reduced below the proportion of one equivalent to one -equivalent of the base, under the new conditions the mineral acid may -be wholly or partially replaced by an organic acid such as formic acid, -without the quality of the black being materially affected. As suitable -oxygen carriers the chlorides of copper have been found to give the best -results, it being preferrable to use the copper in the form of a cuprous -salt. This is effected by adding to the dye mixture cupric chloride, -together with a sulphite or bisulphite in sufficient quantity to reduce -the cupric salt to the cuprous state, and a sufficient quantity of a -soluble chloride to keep the cuprous chloride in solution. Among the -compounds suitable for the production of this black in conjunction with -aniline are, para-phenylene-diamine, dimethyl-para-phenylene-diamine, -para-amido-diphenylamine, para-amido-phenol, etc." - -This method may be used alone as the other Aniline Blacks, or the dyed -skins may be after-dyed in a bath containing a logwood dye, or it may be -used in conjunction with mineral dyes, or with the Oxidation Colors (see -next chapter). A typical formula for the black by Green's process is the -following: - - Para-amido-phenol 0.5 kg. - Aniline oil 10 liters - Hydrochloric acid 22° Bé. 10 liters - Acetic acid 40% 5 liters - Cold water 25 liters - -This is solution A. Solution B is prepared by dissolving - - Copper sulphate 2 kg. - Salammoniac 10 kg. - Cold water 50 liters - -A and B are mixed, and the mixture applied to the hair of the furs several -times, drying each time at 35°-40° C. After three coats of dye have -been applied, a pretty and fairly intense black shade is obtained, which -is developed further by treating with a solution of 25 grams of sodium -bichromate per liter of water. The skins are then allowed to dry in air, -and then if desired, an after-dyeing is made with some other dye. - -On account of its extreme fastness, Aniline Black, produced by any of -the methods outlined above, has attained a justifiable popularity for -the dyeing of furs, in spite of the necessity of using the more or less -cumbersome brush method of applying the dye. Very recently there was -issued to a German company a patent in which is described a method whereby -furs can be dyed with Aniline Black by the dip process. An abstract of -the patent (D. R. P. 33402) is as follows: "As is known, aniline salt, -and similar salts, together with oxidizing agents like bichromates, -chlorates, etc., cannot be used for dyeing furs by the dip process, -because the strongly dissociated mineral acid is injurious to the leather. -The dissociation of the acid can be reduced by adding neutral salts, like -common salt, or Glauber's salt, so that good results can be obtained by -dyeing in a bath of the dye mixture, the leather retaining its softness." - -Thus far there have been no reports of the successful practical -application of this patent, so its value cannot be discussed. It is -extremely doubtful, however, that furs will ever be dyed in the dyebath -with the present type of Aniline Black formulas, no matter what substances -are added to prevent the leather from being affected. - - - - -CHAPTER XV - -FUR DYEING - -OXIDATION COLORS - - -The year 1888 may be considered the beginning of a new era in the -history of fur dyeing; the commencement of a period which was to see -the time-honored, traditional methods of the masters of the art give way -to newer methods of an entirely different character; and moreover, the -initiation of an age when science with its basis of fact and logic, was -to undertake the rationalization of an industry which had hitherto worked -upon a more or less irrational, empirical and uncertain comprehension -of the fundamental principles involved. It was not the work of a single -day, or even of a year which brought about the virtual revolution in the -dyeing of furs, but the result of long, patient, systematic effort. About -this time, the German coal tar industry was attaining its real stride -along the path of progress and achievement, and had already succeeded in -reaching, to an appreciable degree at any rate, most users of coloring -matters, with the consequence that the natural dyes, with their time and -labor-consuming processes of application were gradually being superseded -by the new synthetic dyestuffs which could be simply and quickly applied. -It was now the turn of the fur dyeing industry to receive the attention of -the scientists and technologists responsible for the growth of the coal -tar dye industry, and so there appeared in the above-mentioned year, the -following patents, taken out by a German chemist named Erdmann: - - -D. R. P. 47349 - -A Process for Dyeing Hair and Feathers - -If white hair or feathers are soaked in an aqueous or alcoholic solution -of para-phenylene-diamine, and then exposed to the slow oxidation of -the air, or are treated in a second solution with some oxidizing agent, -then the hair or feathers will be dyed. According to the oxidizing agent -chosen, and the concentration of the solution used, the color obtained -will be light or dark, varying from the palest blond to the deepest -blue-black. Particularly suitable as oxidizing substances are ferric -chloride, permanganates, chlorates, hypochlorites, bichromates, and -hydrogen peroxide. The dyeings are fast, that is, they do not come off, -and the color cannot be removed by washing. Following examples may serve -to make the process clear: - -20 grams pure para-phenylene-diamine and 14 grams caustic soda are -dissolved in a liter of water. The hair, previously degreased, is soaked -thoroughly in this solution, and while moist is entered into a three per -cent solution of peroxide of hydrogen. The action is not instantaneous, -but after a day, the hair is dyed a dark shade; by repetition of these -operations a blue-black is obtained. - -The para-phenylene-diamine can be replaced in this process by other -similar bases, such as dimethyl-para-phenylene-diamine, as well as the -naphthylene-diamines. Since the substances which can be applied by this -process are uninjurious, the method described can be used to dye human -hair on the head or beard, and so seems suited to replace for the dyeing -of hair, the metallic salts and various pyrogallic solutions which are on -the market, and which are harmful to the health. - - -D. R. P. 51073 Supplement to 47349; Process for Dyeing Hair - -This patent was an extension of the original patent to include certain oxy -and amido-oxy compounds, the method being essentially the same otherwise -as in the original patent. An illustration of the process is as follows: - -73 grams para-amido phenol hydrochloride are dissolved with 40 grams -caustic soda in a liter of water. The solution dyes hair a golden-yellow, -which on subsequent treatment with a solution of ferric chloride turns to -a red-brown. - -In these two patents is to be found the basis of the modern fur dyes -and fur dyeing methods. It is interesting to note that furs were not -mentioned at all in connection with the process, which was intended -mainly for dyeing hair, especially on the human head. It was only several -years later that the value of the method for dyeing furs was realized. -So about 1894, the Aktien Gesellschaft für Anilinfabrikation put upon -the market three fur dyes under the trade name Ursol, Ursol D, giving -dark-brown to black shades; Ursol P, giving red-brown colors; and Ursol -C, giving a yellowish-brown shade. Pyrogallic acid had been previously -used as a hair dye, and also to a slight extent as a fur dye, so it was -used in conjunction with the Ursol dyes for shading purposes. The new fur -dyes were not dyes in the ordinarily accepted sense of the term. They -were really coal-tar intermediates, substances similar in character to -aniline, and their dyeing property depended on the fact that they could -be oxidized either by atmospheric oxygen, or by means of oxidizing agents, -forming colored insoluble products. When the oxidation of the intermediate -was caused to take place on the hair the colored product formed on and -in the hair fibre, and remained fast. The reactions bringing about the -conversion of the intermediate to the colored insoluble compound are quite -analogous to those of the Aniline Black process, though possibly not so -complicated, with the important difference, however, that, while in the -production of Aniline Black acid is essential, in the present instance the -oxidation can be carried on in neutral or even alkaline medium. On account -of the character of the method used in applying the new fur dyes, the -name Oxidation Colors has been given to them. Strictly speaking, Aniline -Black is also an Oxidation dye, but it is usually considered in a class -by itself. The methods used at first in the application of the Ursol dyes -to furs followed closely the process as described in the patents. The furs -were first killed, usually by brushing on a lime mixture, drying, and then -beating out the dust. This operation was repeated, if necessary. Then a -solution of the desired dye, mixed with an equal volume of 3% peroxide of -hydrogen was brushed on and the fur allowed to lie exposed to the air. The -dyeing could also be done by the dip process, less concentrated solutions -being used. By varying the concentration of the solution, and prolonging -or shortening the time of action, the shades could be varied from very -light to very dark, and by combining two or more of the Oxidation Colors, -many different color effects could be produced. Soon other fur dyes were -developed and put on the market; for example, Ursol DB, giving blue to -blue-black shades, and Ursol 2G, yielding yellowish tones suitable for -mixing with the other colors. Ursol C was discarded shortly after its -introduction. The dyeings obtained with the Oxidation Colors seemed to be -very fast, resisting successfully the action of cold or hot water, or even -hot soap solution. Moreover, a dyed hair examined under the microscope -appeared to be colored through the epidermis to the medulla, and no -individual particles of dye could be discerned. - -The new fur dyes had many evident advantages over the coloring matters -in general use at the time. The simplicity of the dyeing operations, -the short duration of the process, the great tinctorial power of the -new products, were facts which strongly recommended themselves to the -progressive fur dyer. The cost of the dyes was higher than that of the -vegetable dyes, but this consideration was largely overbalanced by the -saving in time and labor in using them. And yet, the Ursol dyes found -only a comparatively small market. The majority of fur dyers, always -conservative and reluctant to turn from the traditional ways of the -industry were skeptical of, and even hostile towards the new dyes and -the new methods of dyeing. In a sense, this opposition was justifiable. -It was not an easy task to relinquish all at once methods which had -been successfully applied for generations back, and with which they -were thoroughly experienced, in favor of processes which were radically -different, and with which they had no experience at all. But some -enterprising spirits among the fur dyers undertook to try out the new -products and it was not long before the skeptics had good cause for -condemning the work and achievements of the chemists as far as fur dyeing -was concerned. The new type of dyes did possess some of the advantages -claimed for them, but they also possessed many highly objectionable -features, which had never been manifest with the vegetable dyes. First -of all, the dyeings were not so fast as had at first appeared, for the -color came off the hair when the furs were rubbed, brushed or beaten. -Then it was observed that after a short time some of the dyeings changed -color, and at the same time the hair lost its gloss and became brittle. -The condition of the leather after dyeing was anything but satisfactory. -Most serious of all, however, was the appearance among the workers in -the dyeing establishments, and also among the furriers who worked with -the dyed skins, of certain pathological conditions which had hitherto -been unknown. Various skin diseases, eczemas, inflammation of the -eyes, asthmatic affections and intestinal irritations were some of the -afflictions which were directly attributable to the use of fur dyes of -the Ursol type. Medical science was at a loss to know how to treat these -ailments, because their nature was not understood. - -Here indeed, were obstacles threatening to destroy all the hopes which -the discovery of the new class of dyes had aroused, and to check at the -outset the possibility of rational progress in the fur dyeing industry. -But the men of science were not content to let the matter drop thus. -Difficult problems had been solved before, and surely there must be -some way of overcoming the objections and deleterious features of a -system of fur dyeing which had so much potential merit. Where hindrances -sprang up in the path of progress, it was the duty of the chemist to -remove them, and when difficulties arose, it was up to him to resolve -them, as far as was humanly possible. So the chemists who had been -responsible for the introduction of the Oxidation Colors set themselves -to the task of eliminating the undesirable or injurious qualities. It -was many years before the results of painstaking effort and persistent -study cleared up the causes of all the objectionable aspects of the fur -dyes, and suggested means of overcoming them satisfactorily. The work -had been directed to the improvement of the dyes and of the methods of -dyeing with them. Purer intermediates were produced, and more easily -soluble ones, so that there would be no possibility of ultra-microscopic -particles of the dye being deposited on the surface of the hair from the -dye solution, instead of being taken up within the hair fibre. It was -this superficial deposition of minute crystals of the dye or of the only -partially oxidized intermediate, on the hair, crystals so fine as to be -invisible in the ordinary high-power microscope, which caused the color -to come off when the furs were brushed or beaten, giving rise to a dust -which was frequently very injurious to the health. Then, mordants were -adopted to help fix the dyes, compounds of copper, iron, and chromium -being used as formerly with the vegetable dyes, and the range of shades -was also increased thereby. Certain of the Oxidation Colors had a tendency -to sublime off the hair, so the dyed hair was chemically after-treated -in such cases to prevent this. The causes of the pathological aspects of -dyeing with the Oxidation fur dyes were not so readily disposed of. But -the adoption of devices to prevent the formation and circulation of dust -during the handling of the dye, the employment of adequate protection -against contact with the dye or its solutions, the use of the most dilute -solutions possible in dyeing, the thorough washing of the dyed skins to -remove any excess of the coloring matter, the prevention of dust formation -in the drying of the skins, and the rigid observance of, and adherence to -hygienic laws, were all factors in the elimination of the health-impairing -phases of dyeing with the Oxidation Colors. - -It was only after all these improvements had been accomplished that the -fur dye intermediates began to acquire a degree of popularity among fur -dyers, and strange as it may seem, there was a more ready market for -these dyes in America, than in Germany where they were manufactured. Other -manufacturers of coal-tar intermediates also began to produce fur dyes, -and so, in addition to the Ursols, there were the Nako brand, the Furrol -brand, the Furrein brand, and one or two others. New dyes were invented, -until the whole range of colors suitable for fur dyeing had been produced. -The black dye, however, presented some difficulty. A black dye which would -rival logwood blacks could not be attained. Ursol DB in conjunction with -Ursol D was being used to produce bluish-blacks, but the dyeings were not -fast, turning reddish after a time. In 1909, a patent was taken out for -a dye mixture, which was made up like the DB brand, but instead of using -toluylene diamine with para-phenylene-diamine, the new dye was made up of -a methoxy, or ethoxy-diamine with para-phenylene-diamine, and it yielded -brilliant bluish-blacks, which were fast, and which very nearly approached -the logwood black in luster, intensity, and bloom. For some purposes, -however, the production of a black color is still dependent on the use of -the logwood dye. - -When the Great War cut off to a large degree the importation of skins -dyed in Europe, the American fur dyeing industry developed tremendously, -and in a comparatively short time was able satisfactorily to accomplish -in the way of dyeing furs, what had taken foreign dyers a much longer -period to attain. It had been previously considered that furs could be -dyed properly only by European fur dyers, but the achievements in this -direction by Americans fully dispelled this belief. But the success of -the fur dyers in America might not have been so marked or rapid, had it -not been for the work of the American chemists. The war had also shut off -the supply of German dyes, upon which the dyeing industries of America -had formerly been dependent, so enterprising chemists in this country -undertook to fill the need, and in a surprisingly short time, American fur -dyes, in every respect the equal of the foreign product were offered to -the American fur dyers, and at the present time, the requirements of the -fur dyeing industry in this country are being adequately met by domestic -producers. Among the brands on the market are the Rodol, Furamine, -Furol, and several others. The Oxidation Colors are now being offered -in a high state of purity, and easily soluble, free from any poisonous -constituents, and there is absolutely no reason for the appearance of -any pathological conditions among workers on dyed furs, or users of such -furs, provided the necessary precautions have been taken in the dyeing -process. The occurrence of any affection which can be traced to dyed fur, -cannot possibly be due to the dye itself, but to gross carelessness and -negligence in dyeing, and in any such event, the dyer responsible should -be brought to account. - -In order to get a better understanding of the nature and action of the -Oxidation Colors, a typical one will be studied in some detail. The most -important one in this class is para-phenylene-diamine, usually designated -by the letter D in all commercial brands of this fur dye, while its -chemical formula is represented as C{6}H{4}(NH{2}){2}. When pure it occurs -in colorless, crystalline lumps, which rapidly turn brown when exposed -to the air; the technical product of commerce is of a dark-brown color. -It dissolves readily in hot water when pure, and also in acids. At one -time the hydrochloride was used instead of the free base, on account -of its greater solubility, but now a base is made which is sufficiently -pure to be very soluble in water. There are several methods of preparing -para-phenylene-diamine: first, by the reduction of amido-azobenzol, -the product obtained in this way always containing a slight amount of -aniline, which reduces the solubility, and also gives rise to poisonous -oxidation products during the dyeing process; second, by the reduction -of paranitraniline, the quality and solubility of the product in this -case depending on the purity of the starting material; and third, by the -treatment of para-dichloro-benzol with ammonia under pressure, the best -product being obtained by this method. The crude para-phenylene-diamine, -made by any of the above processes, is generally distilled in vacuo, the -refined base being obtained as lumps with a crystalline fracture. - -The first step in the oxidation of the para-phenylene-diamine is the -formation of quinone di-imine, NH:C{6}H{4}:NH. This is a very unstable -compound in the free state, and even in aqueous solution it decomposes -within a comparatively short time, or combines with itself to form a more -stable substance. Quinone di-imine has a very sharp, penetrating odor, and -produces violent local irritations wherever it comes in contact with the -mucous membrane. If a small quantity of para-phenylene-diamine is absorbed -into the human body, by breathing the dust, or otherwise, the formation -of quinone di-imine takes place internally with consequent irritation of -the mucous lining throughout the body. The various pathological conditions -mentioned before may be ascribed to irritation caused by quinone -di-imine. In any dyeing process where there is a possibility of the -formation of quinone di-imine, as is the case with most dyes containing -para-phenylene-diamine, special precautions must be taken by the workers -in handling the dye or coming in contact with its solutions, and no one -who is particularly sensitive to irritation should be permitted to work -in a place where such dyes are used. - -The next step in the oxidation of the para-phenylene-diamine is the -formation of what is called Bandrowski's base. Three parts of the quinone -di-imine combine with themselves, forming a substance of a brown-black -color, which was formerly regarded as the final oxidation product. The -formula of Bandrowski's base is represented by the following chemical -hieroglyphics: - - (NH{2}){2}.C{6}H{3}.N:C{6}H{4}:N.C{6}H{3}(NH{2}){2}. - -Further investigation has shown that the oxidation proceeds beyond this -stage with the formation of a compound of what is known as the azine type, -which is depicted by the chemist as - - NH NH - (NH{2}).C{6}H{3}< >C{6}H{2}< >C{6}H{3}.NH{2}. - NH NH - -It is by no means certain that this substance is the true coloring matter -obtained by the oxidation of para-phenylene-diamine, for the reactions -may continue still farther, producing even more complicated oxidation -products. Scientific research and study has not as yet gone beyond this -stage. - -The reactions of the other dyes of the Oxidation type are quite similar to -those of para-phenylene-diamine, some being simpler, and others being even -more complex. The presence of certain chemical groups in the intermediate, -or the relative position of such groups are factors responsible for the -variations in shade. - -With the various mordants, the Oxidation Colors give different shades, and -a great range of colors can be produced either by combining mordants, or -combining dyes, or both. The following tables illustrate the shades formed -with the customary mordants. - - ========================================================================= - | CHROME | COPPER | IRON | DIRECT - ---------+---------------+----------------+--------------+--------------- - Ursol D | brown black | coal black | coal black | dark brown to - | | | | brown black - Ursol P | dull red brown| dull dark brown| grey brown | light brown - Ursol 2G | yellow brown | dull yellow | yellow brown | dull yellow - | | brown | | - Ursol A | ... | ... | blue black | blue to blue- - | | | | black - Ursol 4G | light brown | medium brown | yellow | pure yellow - Ursol 4R | orange brown | light yellow | red brown | orange red - | | brown | | - Ursol | | | | - Grey B | greenish grey | greenish grey | mouse grey | ... - Ursol | | | | - Grey R | brownish grey | brownish grey | reddish grey | ... - ---------+---------------+----------------+--------------+--------------- - -Fur dyes of American make being equal in every way to the German product, -show the same color reactions with the various mordants. The following -table shows the shades produced with the same mordants as above: - - ========================================================================= - | CHROME | COPPER | IRON | DIRECT - ---------+---------------+---------------+---------------+--------------- - Rodol D | brown black | coal black | coal black | brownish black - Rodol P | red brown | dark brown | grey brown | light brown - Rodol 2G | yellow brown | yellow brown | yellow brown | dull yellow - Rodol 4G | light brown | light brown | reddish brown | pure yellow - Rodol A | ... | blue black | ... | blue black - Rodol | | | | - Grey B | greenish grey | greenish grey | mouse grey | ... - Rodol | | | | - Grey R | greenish grey | brownish grey | mouse grey | ... - ---------+---------------+---------------+---------------+--------------- - -All these shades are produced by dyeing in a bath containing a _neutral_ -solution of the dye. Sometimes the dye comes in the form of a salt of -a mineral acid, like hydrochloric or sulphuric acid, in which case a -sufficient amount of an alkali, usually ammonia, is added to liberate -the free base. According to the Cassella Co., German manufacturers of the -Furrol brand of fur dyes, the dyeing can also be carried on in slightly -alkaline or in slightly acid solution, a different series of shades being -obtained in each instance. Ammonia is used to render the bath alkaline, -and formic acid to make it acid. The most customary practise, however, is -to use neutral solutions of the dyes. - -For preparing the mordant solutions much smaller quantities of the -metallic compounds are used than in the case of the vegetable dyes. With -chrome mordants cream of tartar is always employed as an assistant, and -occasionally also with copper and with iron mordants. With copper, and -also with iron mordants no addition is made at all, or sometimes a small -quantity of acetic acid is added. The temperature of the mordant solution -is kept about 30° C., and the duration of the mordanting varies from 2-24 -hours according to the depth of shade desired. The concentration of the -solution may also be varied, it sometimes being just as well to use a -strong mordant solution and less duration of mordanting. Chrome may be -combined with copper, and iron may be combined with copper, but chrome -and iron do not go together as mordants. Some typical average mordanting -formulas are as follows: - - Chrome mordant. - Bichromate of soda 2.5 gms. - Cream of tartar 1.5 gms. - Water 1 liter - - Copper mordant. - Copper sulphate 2 gms. - (Acetic acid 50% 2 gms.) - Water 1 liter - - Iron mordant. - Ferrous sulphate 2 gms. - (Acetic acid 50% 2 gms.) - Water 1 liter - -or, - - Iron pyrolignite 30% 10 gms. - Water 1 liter - - Chrome-copper mordant. - Bichromate of soda 2 gms. - Copper sulphate 0.25 gms. - Cream of tartar 1.0 gms. - Water 1 liter - - Copper-iron mordant. - Copper sulphate 2 gms. - Ferrous sulphate 2 gms. - (Acetic acid 50% 2 gms.) - Water 1 liter - -The killed skins are immersed in the mordanting solution, and allowed -to remain the required length of time. They are then thoroughly rinsed -to remove any excess of the mordant, and are hydro-extracted. Under no -circumstances should mordanted skins be permitted to dry, for they would -be unfit for use again. - -The dyebath is next prepared by dissolving the necessary quantity of the -dye, varying from 0.1 gm. to 10 gms. per liter. Then if the solution must -be neutralized, the ammonia is added and the temperature of the bath is -brought to 30-35° C. by the addition of cold water. This temperature is -maintained throughout the dyeing operation. To the solution is added the -oxidizing agent. Ordinary commercial peroxide of hydrogen containing 3% -by weight is the usual oxidizer, although perborates have been suggested. -15-20 parts of peroxide of hydrogen for every part of dye are added, and -the dye solution brought to the proper dilution. As soon as the dyebath is -ready, the skins are entered, and worked for a short time to effect even -penetration. They are then left in the dyebath for 2-12 hours or longer -according to the depth of shade. After being satisfactorily dyed, the furs -are rinsed thoroughly, hydro-extracted and dried and finished. Where the -dye is to be applied by the brush to the tips of the hair, stronger dye -solutions are used, the brushed skins being placed hair together and let -lie for about 6 hours in order to permit the color to develop, after which -the furs are dried and drum-cleaned. - -Some shades, particularly black, have a tendency to rub off slightly. In -order to overcome this, the dyed furs, after rinsing, are treated with a -cold solution of 1/2 part of copper sulphate per 1000 parts of water, for -3-4 hours, then without rinsing, hydro-extracted and dried. Furs which -have been tipped are brushed with a 1-2% solution of copper sulphate and -dried. Care must be taken in this after-treatment, for the use of too -strong a solution of copper sulphate, or too prolonged action of such a -solution will materially alter the shade of the dyed fur. - -A few typical formulas will serve to illustrate the general methods of -employing the Oxidation Colors: - - -_Brown Sable Imitation on Unsheared Rabbit_ - -The skins are killed with soda, soured, and washed, then mordanted with - - Bichromate of soda 2 grams - Copper sulphate .25 grams - Cream of tartar 1 gram - Water 1 liter - -for 24 hours. Then washed, and dyed for 24 hours with - - Fur Brown 2G[3] 3 grams - Hydrogen peroxide 45 grams - Water 1 liter - -Wash and dry the skins, then brush the tips with - - Fur Brown D[3] 20 grams - Hydrogen peroxide 400 grams - Water 1 liter - - [3] Inasmuch as most manufacturers use the same letters to designate - the various dyes, any equivalent brand of fur dye may be used in - place of those here mentioned. - - -_Black on Sheared Muskrat_ - -The skins are killed with soda, soured, and washed, then chrome mordanted -for 6 hours. Then they are dyed for 6 hours with - - Rodol P 1.5 grams - Pyrogallic acid .7 grams - Ammonia 2.0 grams - Hydrogen peroxide 45 grams - Water 1 liter - -The dyed skins are washed and dried, then tipped with - - Rodol D 20 grams - Rodol DB 2 grams - Hydrogen peroxide 450 grams - Water 1 liter - - -_Brown on Thibet Sheep Skin_ - -The killed skins are mordanted for 6 hours with a chrome mordant, then -dyed for 6 hours with - - Ursol P 1 gram - Pyrogallic acid 1 gram - Ammonia 2 grams - Hydrogen peroxide 40 grams - Water 1 liter - -It is also possible to combine dyeings with the Oxidation Colors with -Vegetable dyeings, or with Aniline Black. For example, if it be desired -to produce an imitation skunk on a raccoon, and an exceptionally fast and -intense and lustrous black on the tips of the hair, the skins are dyed -in the bath with the Oxidation dyes, and the tips of the hair are brushed -with a mixture such as described under Vegetable Colors for the production -of French seal, as follows: - - -_Imitation Skunk on Raccoon_ - -The skins are killed with caustic soda, soured and washed, then mordanted -with an iron-copper mordant as described, and then dyed with - - Fur Grey R 3 grams - Ammonia 2 grams - Peroxide of hydrogen 45 grams - Water 1 liter - -After washing and drying, the dyed skins are brushed over with a mixture -such as used for dyeing French seal with Vegetable Colors. - -In a similar manner, the Oxidation Colors may be used to give a base color -to furs dyed by the Aniline Black process. - -It is apparent from these few illustrations that a great variety of shades -can be produced, and the dyeing of imitations of the better class of furs -on cheaper skins is a comparatively simple matter, after an understanding -of the nature of the dyes has been obtained, and a certain amount of skill -acquired in working with these dyes. - - - - -CHAPTER XVI - -FUR DYEING - -COAL TAR DYES - - -In addition to the Aniline Blacks and the Oxidation Colors already -discussed there are certain of the synthetic coal tar dyes such as are -generally used in the dyeing of textiles, which can also be applied on -furs. There are several classes of these dyes, varying somewhat in their -nature, and consequently in their manner of application; in the main they -produce bright shades, such as are but seldom used on furs, yet which may -occasionally serve for the production of novel effects. Basic, acid and -chrome colors are the types which can be employed. - -Basic colors possess great fullness and tinctorial strength, but have a -tendency to rub off, and the tips of the hair take a darker shade with -these dyes than the rest of the hair. The addition of acetic acid and -Glauber's salt to the dyebath will result in a more uniform dyeing. On -account of the comparatively poor fastness to rubbing and washing, basic -dyes are used only for dyeing furs which are intended for cheap carpet -rugs, such as sheep and goat. They may also find use in the production -of light fancy shades on other white furs. The procedure is usually as -follows: The furs are killed in the customary manner with soap and soda -or ammonia, or if this is insufficient, with milk of lime. A soap-bath is -then prepared containing 2.5-6 grams of olive-oil soap per liter of water. -The temperature of the bath is brought to 40° C. To this is added the -solution of the dyestuffs, prepared by mixing the required color or colors -with a little acetic acid to a paste, and then pouring boiling water on -the mixture until dissolved. Undissolved particles or foreign matter are -removed by passing this solution through a cotton cloth or sieve, and -the clear solution then mixed with the soap-bath. The well-washed skins -are then entered into the dyebath and immersed for about half an hour, -or until the desired depth of shade is obtained. They are then removed, -pressed or hydro-extracted and dried. For the production of light shades, -the following dyes may be used: - -For cream, light sulphur-yellow, maize, salmon, etc. - Combinations of - Thioflavine - Rhodamine B - Irisamine G - -For greenish-yellows - Combinations of - Thioflavine - Victoria Blue B - -For light pink - Rhodamine B - Irisamine - Rose Bengal Extra N - -For purple - Methyl Violet 3B-6B - Crystal Violet - -For sky-blue - Victoria Blue B - -For white - Victoria Blue B (Milk-white) - Methyl Violet 3B-6B - Crystal Violet (Ivory-white) - -To produce very delicate shades, the moist dyed skins are subjected to a -sulphur bleach overnight, to lighten the color, then rinsed, and dried. -Full, brilliant shades may be obtained by dyeing in a bath of 40° C., -acidulated with 2-3 grams of acetic acid per liter of solution, the -following dyestuffs being suitable: - -For yellow to orange - Thioflavine - Paraphosphine - Rhodamine - Safranine - New Magenta O - -For pink - Rhodamine B - Rose Bengal Extra N - -For light red - Safranines - -For bordeaux and red - Magenta - New Magenta - Russian Red - Cerise - -For violet - Methyl Violet 6B-4R - Crystal Violet 5B - -For blue - Victoria Blue B - Methylene Blue BB - New Methylene Blue N - -For green - Malachite Green Crystals - Brilliant Green Crystals, or combinations of - Thioflavine - Diamond Phosphine - Victoria Blue B - -For brown - Chrysoidines - Bismarck Browns - -In dyeing skins with harder hair than that of sheep or goat, mere killing -is insufficient to render the hair capable of taking up the dye. The -skins are therefore immersed before dyeing, in a cold, weak solution -of chloride of lime, the affinity of the hair for the dye being thereby -greatly increased. - -Acid dyes are employed when a greater fastness is required than can be -obtained with the basic colors. Sulphuric acid in a quantity equal to -half the weight of the dyestuffs used, together with four times that -quantity of Glauber's salt is added to the dyebath. Formic acid may be -used in place of the sulphuric acid, very good results being obtained. -The skins are immersed in the dyebath, and worked until thoroughly soaked -with the dye liquor, and then allowed to remain until the proper depth -of shade is attained, or overnight. The temperature of the solution is -about 40° C., and only very light shades can be produced in this manner. -In 1900 and again in 1914, the Cassella Co., a large German manufacturer -of dyestuffs, obtained patents for processes enabling the dyeing of -furs in hot solution with the acid dyes. The method required that the -skins be chrome-tanned in order to render them resistant to the action -of hot solutions, the addition of a small amount of formaldehyde to the -chrome solution increasing this effect. The skins are then treated with a -solution of chloride of lime in order to increase the affinity of the hair -for the dyestuffs. The method as it is now practised is as follows: The -skins which have been cleaned and washed are chrome tanned by the method -as described in the chapter on Tanning Methods, 60 grams of formaldehyde -being added to every 10 liters of the chrome solution. After proper -tanning the skins are rinsed, and while still moist they are subjected to -a treatment with chloride of lime. They are first immersed for 15 minutes -in a cold bath containing 120 grams of hydrochloric acid 32-36° Twaddell -per 10 liters of water, then without rinsing, they are entered into a bath -made up by adding gradually in four portions the clear solution of 2-4 -grams of the chloride of lime per 10 liters of water. After working for -an hour, the skins are removed and entered again into the acid solution, -in which they are worked for another 15 minutes. In order to neutralize -and remove the last traces of the chloride of lime from the furs, they are -rinsed in a luke-warm bath containing 1-2 grams of sodium thiosulphate, -or hyposulphite of soda, in 10 liters of water. The skins are then rinsed -again, and hydro-extracted, or pressed, and are ready for dyeing. The -dyebath is prepared with the required quantity of dye, to which is added -10-20% Glauber's salt and 2-5% acetic acid (both calculated on the weight -of the skins). The skins are entered at 20° C., then after three-quarters -of an hour to 40° C., and then after another hour slowly to 50-55° C. For -blacks, the temperature is raised as high as 65° C. After dyeing the skins -are treated with a solution containing per 10 liters - - 90-120 grams of olive-oil soap - 12-25 grams olive oil - 12 grams ammonia - -for 15 minutes, then hydro-extracted and dried, without further rinsing. - -For this method of dyeing, the following dyes may be used: - -For yellow and orange - Fast Yellow S - Acid Yellows - Naphthol Yellow S - Tropaeoline - Orange GG, R, II, IV - -For reds - Acid Reds - Lanafuchsine - Azo Orseille - -For violet - Azo Wool Violet - Acid Violets - -For blue - Cyanole FF - Azo Wool Blue - Naphthol Blue R - Formyl Blue B - -For green - Naphthol Green B - Fast Acid Green - Cyanole Green - -For brown, combinations of - Fast Yellow S - Acid Yellows - Tropaeoline DD - Orange GG - Lanafuchsine - Indigo Blue N - Cyanole B - Fast Acid Green BN - -For black - Naphthylamine Blacks - Naphthol Blacks - Naphthol Blue-black - -For grey - Silver Grey N - Dyed with the addition of 1/2-1% of alum - -The chrome colors are dyed on furs when very fast shades are desired, all -the fancy colors being produced in this manner, but for black, only the -acid dyes are suitable. The preparation of the skin is exactly the same as -for the acid colors, except that the treatment with chloride of lime may -be omitted, although for very full shades it is desirable. The dyeing is -carried out as follows: The dyebath is prepared with the requisite amount -of the desired dyestuff, which is previously dissolved, and to this is -added a solution of sodium bichromate, the amount of this substance being -half the weight of the dye. The solution is heated and the skins entered -and dyed for 1-2 hours at 70-80° C. Then the dyebath is exhausted by the -addition of 1/3% acetic acid, the skins being worked for another half -hour, then rinsed, hydro-extracted and dried. Any of the one-bath chrome, -or after-chrome colors may be used for this method. - -Recently methods have been patented for the dyeing of furs by means of -the vat colors. Vat dyes are among the fastest coloring matters ever -produced, and their application on furs would be a great advantage, if -suitable shades could be obtained. The general process for dyeing with vat -colors, consists in reducing the dye, which is usually very insoluble, -into a soluble "leuco" compound, by means of hydrosulphites in the -presence of alkalies. The leuco compound is not a dye itself, but when -the fibre absorbs it, and is then exposed to the air, the leuco compound -is reoxidized to its original insoluble form, which remains fast and -permanent. The use of strong alkalies in vat dyeing has hitherto been a -great obstacle in the use of these dyestuffs, but in 1917, the Farbwerke -Hoechst, a large German dye works, patented a process as follows: "A -process for dyeing furs with vat colors. The dyeing is done in solutions -of the vat dyes (after the addition of gelatine or some other protective -colloid), which are rendered neutral or only slightly alkaline with -ammonia, by neutralizing the caustic soda of the solution of the leuco -compound of the vat dyes by the addition of ammonium salts, or suitable -acids. The dyeings thus obtained are uniform and fast, the leather is dyed -to only a slight degree, and shows no deleterious effects of the dyebath -on the tannage." As a practical application of this process, another -patent was taken out by the same company, also in 1917, as follows: -"A process for producing fast blacks on furs, consisting of dyeing a -ground color with appropriate vat dyes in a hydrosulphite vat, and after -oxidation in air, topping with an Aniline or Diphenyl black. The dyeings -obtained by the combination of vat dyes which are fast to oxidizing -agents, with an oxidation black, have an appearance matching that of -logwood black in beauty; and with a dark-blue to blue-black under-color, -and a full, deep black top color, cannot be distinguished from logwood. -These dyeings also have the advantage of being faster to light than -logwood or other blacks." - -While these processes undoubtedly have many meritorious qualities which -make them interesting, they do not seem as yet, to have attained any -great practical application. However, it is a field of fur dyeing which is -worth while developing, and with certain necessary improvements in these -processes, the vat dyes may yet supersede partially some of the other -methods of dyeing furs. - - - - -CHAPTER XVII - -BLEACHING OF FURS - - -Bleaching is for the purpose of lightening the color of furs, and is -most generally applied to white-haired skins such as white fox, ermine, -and occasionally white lambs of all kinds, and white bears. Among such -furs, pelts of a naturally pure white tone are relatively scarce, while -in the majority of cases the color ranges from a pale creamy white to a -decidedly yellowish shade. Colors which vary from the pure white detract -considerably from the attractiveness and consequent value of the fur, and -indeed, some pelts are so far off shade that they can only be used when -dyed a darker color. Most white skins which are but slightly inferior in -color can be brought to a pure white by bleaching, and they can then be -used natural. Some pelts, on the other hand, are particularly resistant -to the action of bleaching agents and cannot be sufficiently decolorized -to render them suitable for use natural, so these are also dyed. For the -production of certain delicate or fancy dyed shades on white furs, it is -often necessary to bleach the skins in order to be able to obtain pure -tones. Such instances are not very common, however. Occasionally dark -furs, such as beaver, are bleached on the tips of the hair, a golden shade -being obtained thereby, which at one time was quite popular, but recently -such effects have not been in vogue. - -In the bleaching of furs, two steps may be distinguished, first -degreasing, and second, bleaching proper. In the preliminary operations -of fur dressing, the furs are treated with soap or weak alkalies to -cleanse them and to remove excess oil from the hair. During the various -processes and manipulations, the hair, especially on white skins, may -become soiled or somewhat greasy again, so it is advisable to repeat -the cleaning process. This should in every case be as light as possible, -using a weak solution of soap for the softer and cleaner pelts, or dilute -solutions of ammonium carbonate or soda ash for the more greasy-haired -skins. The skins are then thoroughly rinsed to remove all traces of -the degreasing material. This step is very essential in order to obtain -uniform bleaching. - -Broadly speaking, there are two general methods which can be used in -bleaching furs, one involving the use of what are known as reducing -agents, and the other employing oxidizing substances. - -Among reducing agents which can be used for bleaching furs are sulphurous -acid, and its salts such as sodium bisulphite and sodium sulphite; -hydrosulphites, and derivatives. - -1. ~Sulphurous acid.~--When sulphur is burned, sulphur dioxide gas -is formed. In the presence of moisture, or when dissolved in water, -this gas forms sulphurous acid, which is one of the most commonly used -bleaching chemicals for all sorts of materials, and is very effective -for decolorizing furs. The procedure usually followed is to hang up the -moistened skins on wooden rods in a more or less cubical chamber made of -stone or brick, and lined with wood or lead. No other metals may be used, -because they are quickly corroded by the sulphurous acid. The requisite -quantity of sulphur is placed in a pot in the bleaching chamber, and then -ignited, after which the doors are shut tight. The fumes of the burning -sulphur in contact with the moist hair readily exert their bleaching -action on the furs, and the operation is allowed to proceed for six or -eight hours, or overnight. Then by means of fans or other devices, the -air filled with sulphur dioxide gas is withdrawn from the chamber, and -replaced by fresh air. The door is opened, the skins removed, exposed to -the air for a time, then rinsed, and finally dried and finished. Sometimes -one operation is not enough to sufficiently bleach the hair, so the -process is repeated. Sulphur dioxide gas can now be obtained compressed -in cylinders, which are more convenient to handle than burning sulphur. -The flow of gas which is introduced into the bleaching chamber by means -of a nozzle attached to the cylinder, can be regulated, and the bleaching -thus retarded or accelerated. - -2. ~Sodium bisulphite and sodium sulphite.~--These salts of sulphurous -acid are effective in their bleaching action only when in solution in the -presence of acids. The acids liberate sulphurous acid from the salts, -so this method is virtually the same as 1. Instead of using the salts -of sulphurous acid, sulphur dioxide may be dissolved in water, and the -solution used for bleaching by immersing the furs in it. This procedure, -while consuming somewhat less time than the chamber process, is more -likely to affect the leather, which would have to be retanned. The -principle is the same as that involved in method 1. - -3. ~Hydrosulphites and derivatives.~--The bleaching agent can be prepared -by adding zinc dust to commercial bisulphite of soda dissolved in about -four times its weight of water until no more reaction is evident. Milk -of lime is then added to precipitate the zinc, and the clear supernatant -liquid of 1.5°-5° Tw. is used for bleaching. The skins are immersed -for 12-24 hours, taken out, washed and finished. Instead of preparing -the hydrosulphite, the commercial products may be used with greater -convenience, a solution containing 1-4% of the hydrosulphite powder being -used, and the skins treated in this until satisfactorily bleached. - -The bleaching action of sulphurous acid and hydrosulphite is supposed to -be due to the reduction of the coloring matter of the hair to a colorless -compound; or possibly to the formation of a colorless compound of the -bleaching material with the pigment. The former seems the more probable -explanation, because the change is not a permanent one, the original -natural color returning after a long exposure of the bleached fur to air -and light. However, the results are sufficiently enduring to satisfy the -requirements of the trade in the class of furs on which these methods of -bleaching are used. - -Bleaching chemicals with an oxidizing action generally used for -decolorizing furs are hydrogen peroxide and peroxides; occasionally -hypochlorites and permanganates are also used. - -1. ~Hydrogen peroxide.~--Hydrogen peroxide is usually employed for -bleaching in the form of its 3% solution, to which is added about 20 -cubic centimeters of ammonia per liter. The ammonia serves partially to -neutralize the acid which commercial peroxide generally contains, and -also to facilitate the bleaching action. The thoroughly degreased skins -are immersed in the solution until the hair is completely wetted by it, -are then removed, and evenly pressed or hydro-extracted, after which -the pelts are hung up to dry in the air. As the hair becomes drier, -the concentration of the peroxide becomes greater, and consequently the -bleaching action is stronger. Where there is a likelihood of the leather -being affected by the bleaching solution, the ammoniacal peroxide may -be applied to the hair with a fine sponge or brush until sufficiently -wetted, and then hanging the skins up to dry. Repetition of the process -is sometimes necessary to obtain pure white, but the results are always -excellent. - -2. ~Peroxides.~--The most important of these is sodium peroxide, which -comes on the market as a yellowish-white powder, which must be kept dry, -and away from any inflammable material, as fires have been caused by the -contact of the peroxide with such substances. When dissolved in water, it -is equivalent to a strongly alkaline solution of peroxide of hydrogen. - - Na{2}O{2} + 2H{2}O = H{2}O{2} + 2NaOH - sodium water peroxide caustic - peroxide of soda - hydrogen - -When dissolved in acid, the alkali is neutralized, and a neutral solution -of peroxide of hydrogen and a salt is obtained, and this method is used -to obtain peroxide of hydrogen cheaply. - - Na{2}O{2} + H{2}SO{4} = H{2}O{2} + Na{2}SO{4} - sulfuric sodium - acid sulphate - -3 parts of sodium peroxide are slowly dissolved in a cold 1% solution of -4 parts of sulphuric acid, stirring during the addition, and making the -resulting solution neutral to litmus paper, acid or more sodium peroxide -being added as needed. There is then added 3-6 parts of a solution -of silicate of soda of 90° Tw. The skins are immersed until properly -bleached, taken out, passed through a weak acid solution, then washed -and finished. This method generally requires the leather to be retanned -after bleaching. Another process, which involves the use of peroxides, -but which is not commonly practised, consists in rubbing the hair with -a pasty mixture of equal parts of water, barium dioxide, and silicate of -soda, hanging up the skins to dry, and then beating and brushing the hair. - -3. ~Permanganates.~--The only member of this group that finds practical -application for bleaching purposes is potassium permanganate. The skins -are immersed in a 0.1% solution of the crystals of potassium permanganate, -until the hair acquires a deep brown color. They are then removed, rinsed, -and entered into a second bath containing sulphurous acid in solution, -prepared by acidifying a solution of sodium bisulphite. The skins are then -worked in this until fully bleached. It is the permanganate which does -the bleaching, the sulphurous acid being for the purpose of dissolving -the brown compound of manganese formed on the hair. - -4. ~Hypochlorites.~--Chloride of lime and sodium hypochlorite, which is -prepared from the former, are the chief chemicals of this type used for -bleaching. The skins are entered into a weak solution of the hypochlorite, -and left until the hair is decolorized; then after removing, they are -passed through a dilute acid, and subsequently through a weak solution of -sodium thiosulphate in order to remove all traces of the hypochlorite. -This method causes the hair to acquire a harsh feel, and the yellow -color is never entirely eliminated. The hair, however, possesses a -great affinity for certain types of dyestuffs, and it is only when -these particular classes of dyes are to be applied to the furs, that the -hypochlorite bleach is used. (See dyeing with Acid colors). - -The various oxidation methods of bleaching are supposed to change the -coloring matter of the hair into an entirely different and colorless -compound which cannot return to its original form. The bleach is therefore -permanent. - -In common practise, the sulphurous acid, and the peroxide of hydrogen -methods are the two chiefly employed in bleaching processes. Sulphurous -acid is used to bleach the cheaper kinds of furs, while peroxide of -hydrogen is applied to the finer furs. - -Whichever process is used, it is customary to give the bleached skins a -subsequent "blueing," by passing them through a very weak solution of a -blue or violet dye, such as indigo-carmine, crystal violet, alkali blue -or ultramarine. The furs are then dried and finished off as usual. In drum -cleaning white furs, gypsum or white sand, or sometimes even talc are used -with the sawdust, or occasionally alone without the sawdust. - - - - -BIBLIOGRAPHY - - - Allen "Commercial Organic Analysis" - - Armour, B. R. "Fur Dressing and Dyeing" 1919 - - ---- Color Trade Journal, Vol. 1, p. 51-53 - - ---- Jour. Amer. Leather Chemists' Assn., Vol. 13, p. 63-69. - - Belden, A. L. "Fur Trade in America" 1917 - - Beltzer, F. J. G. "Industrie des Poils et Fourrures, etc." 1912 - - ---- Revue Generale des Matieres Colorantes, Vol. 12, 1908 - - Bennett, H. G. "Manufacture of Leather" 1910 - - Bertram, P. Deutsche Färber-Zeitung 1895-96 Heft 17, p. 266 - - Bird, F. J. "American Practical Dyers' Companion" p. 241-245 - - Boerner, H. Kunststoffe, 1912 p. 223 - - Brevoort, H. L. "Fur Fibres as shown in the Microscope" 1886 - - Bucher, B. "Geschichte der technischen Künste" 1875-1893 - - Cubaeus, P. "Das Ganze der Kürschnerei" 1912 - - Davis, C. T. "Manufacture of Leather" - - Erdmann, E. Deutsche Färber-Zeitung 1894-95 Heft 21, p. 337 - - ---- Zeitschrift für angewandte Chemie, 1895, Heft 14 - - ---- Zeitschrift für angewandte Chemie, Heft 35, 1905 - - ---- Berichte, 1904, 37, p. 2776, 2906 - - Farrell, F. J. "Dyeing and Cleaning" 1912 - - Fleming, L. "Practical Tanning" 1916 - - Fougerat, L. "La Pelleterie dans l'antiquité, la préhistoire, etc." - - Gardner, W. M. "Wool Dyeing" 1896 - - Grandmougin, E. Zeitschrift für Farben-Industrie, 1906, 5, p. 141 - - Gruene, E. Deutsche Färber-Zeitung, 1895-96 Heft 13, p. 197 - - Halle "Werkstätte der heutigen Künste," 1762, Vol. 2, p. 317 - - Hartwig, O. L. "Sprengler's Künste und Handwerke," 1782 - - Hausman, L. A. Scientific Monthly, Jan. 1920; March, 1921 - - ---- Natural History, Vol. 20, 4, 1920 - - ---- American Journal of Anatomy, Sept. 1920 - - ---- American Naturalist, Nov.-Dec. 1920 - - Hayes, A. H. National Cleaner and Dyer, Nov. 1920, p. 55-57 - - Jacobson, "Schauplatz der Zeugmanufacturen" p. 493 - - Jones, J. W. "Fur Farming in Canada" 1913 - - Knecht, Rawson & Loewenthal "Manual of Dyeing" 1916 - - Kobert, R. "Beitrage zur Geschichte des Gerbens und der - Adstringentien" 1917 - - Koenig, F. Zeitschrift für angewandte Chemie, 1914, Vol. 1, p. 529 - - Lamb, J. W. Jour. Soc. Dyers & Colourists Dec. 1905, p. 323 - - Lamb, M. C. "Dressing of Leather" 1908 - - ---- Jour. Soc. Dyers & Colourists 1913, 29, p. 160-165 - - Larish & Schmid "Das Kuerschner Handwerk" 1-3 - - Laut, A. C. "The Fur Trade of America" 1921 - - Lightfoot, J. "The Chemical History & Progress of Aniline Black" - 1871 - - Mairet, E. M. "A Book on Vegetable Dyes" 1916 - - Martin, G. "Industrial Organic Chemistry" - - Matthews, J. M. "Application of Dyestuffs" 1920 - - Mayer, A. "Die Färberei in der Werkstätte des Kürschners" - - Mierzinski, S. "Die Gerb und Farbstoffextrakte" - - Noelting & Lehne "Anilin-Schwarz" 1904 - - Perkins & Everest "Natural Organic Coloring Matters" 1918 - - Petersen, M. "The Fur Traders & Fur-Bearing Animals" 1920 - - Poland, H. "Fur-Bearing Animals in Nature and Commerce" - - Proctor, H. "Leather Industries Laboratory Book" - - ---- "Tanning" - - ---- "Making of Leather" - - Schlottauer, E. Deutsche Farber-Zeitung 1911, Heft 20, p. 397 - - ---- Deutscher Färber-Kalender 1911, p. 65 - - ---- Leipziger Färber-Zeitung 1909, p. 441 - - Schmidt, C. H. "Handbuch der Weissgerberei" - - Setlik, B. Deutsche Färber-Zeitung 1901, p. 213 - - Smith, R. W. Color Trade Journal Vol. 3, Sept. 1918, p. 304-310 - - ---- Textile Recorder, Vol. 36, p. 292-293, Dec. 1918 - - ---- Revue Generale des Matieres Colorantes, Vol. 23, p. 32-36 - - Stevenson, C. H. "U. S. Fish Commission Report 1902-1903", Bulletin - No. 537 - - Stickelberger, E. "Geschichte der Gerberei" 1915 - - Strasser "Chemische Färberei der Rauchwaren" 1879 - - Ullmann "Enzyklopedie der technischen Chemie" - - Villon, A. M. "Traité pratique de la fabrication des cuirs, etc." - 1900 - - Werner, H. "Die Kürschnerkunst" 1914 - - ---- "Das Färben der Rauchwaren" 1914 - - Whittaker, C. M. "Dyeing with Coal Tar Dyes" 1919 - - Wiener, F. "Weissgerberei" 1877 - - Witt-Lehman "Chemische Technologie der Gespinst-Fasern" 1910 - - Zeidler, H. "Die moderne Lederfabrikation" 1914 - - - - -INDEX - - - Acetate, aluminum, 118 - - ---- chromium, 120 - - ---- copper, 120 - - ---- ferrous, 119 - - ---- lead, 126 - - Acetic acid, 112 - - Acid dyes, 174 - - Acids, action of, on hair, 29 - - ---- ---- on skin, 26 - - After-treatment with copper, 168 - - Alaska fox imitations, 143 - - Alkaline aluminum mordants, 122 - - ---- chromium mordants, 123 - - ---- iron mordants, 123 - - Alum, 32, 53, 118 - - ---- chrome, 57 - - ---- -chrome tans, 64 - - ---- tans, 54, 56 - - Aluminum acetate, 118 - - ---- mordants, 118 - - ---- sulphate, 53, 118 - - Ammonia, 110 - - Ammonium sulphide, 126 - - Aniline black, 144 - - ---- ---- by dip process, 154 - - ---- ---- chemistry, 145 - - ---- ---- Green's process for, 152 - - ---- ---- nature of, 144 - - ---- ---- One-bath, 149 - - ---- ---- Oxidation, 150 - - ---- ---- processes, 149 - - ---- ---- ungreenable, 148 - - Aniline oil, 145 - - Astrachan 5, 7, 12 - - - Bacteria, 51 - - Badger, 7 - - Ball-drum, 62 - - Bandrowski's base, 164 - - Basic dyes, 171 - - Beam, 38 - - Beaming, 38 - - Bear, black, 5, 7 - - ---- brown, 5, 8 - - ---- white, 8 - - ---- ---- bleaching of, 179 - - Beating furs, 79 - - Beaver, 5, 8, 25, 83, 94 - - Beechwood ashes, 108 - - Bichromate of soda, 121, 147 - - Black, aniline, 144 - - ---- ---- by Green's process, 152 - - ---- ---- chemistry of, 145 - - ---- ---- nature of, 144 - - ---- ---- One-bath, 149 - - ---- ---- Oxidation, 150 - - ---- ---- ungreenable, 148 - - Black, diphenyl, 152 - - ---- logwood, 139 - - ---- on Chinese goats, 141 - - ---- on lambs, 141 - - ---- on raccoon, 130 - - ---- on skunk, 130 - - ---- on wolf, 130 - - Bleaching of furs, 179 - - Blending, 91, 104 - - Blue-grey on white furs, 142 - - Blueing, 184 - - Blue salt, 120 - - ---- vitriol, 119 - - Borax, 39, 58 - - Brasilein, 135 - - Brasilin, 135 - - Brazilwood, 135 - - Bright shades on furs, 171 - - Broadtail, 8, 12 - - ---- dyeing of, 139 - - Brown on Thibet sheep, 169 - - ---- with natural dyes, 142 - - Brush process, 98 - - Brushes used in dyeing, 100 - - Butter, 60, 63 - - - Cage, 80 - - Cageing, 80 - - Campeachy wood, 133 - - Caracul, 8, 12 - - ---- dressing of, 53 - - Caracul, dyeing of, 140 - - Carnivorous animals, furs of, 37 - - Cased skins, 36 - - Castor oil, 60, 63 - - Cat, civet, 5, 8 - - ---- house, 8 - - Caustic soda, 44, 110, 113 - - Centrifugal machine, 40 - - Chamber drying, 73 - - Chamois dressing, 31 - - ---- tan, 49, 58, 61 - - Characteristics of tans, 65 - - Chestnut extract, 133 - - Chinchilla, 5, 6, 8, 94 - - ---- blending of, 91, 104 - - Chinchillone, 9 - - China goat, black on, 141 - - Chlorates, 147 - - Chloride of lime, 174 - - ---- ---- bleach, 184 - - Chrome acetate, 120 - - ---- alum, 57, 120 - - ---- colors, 176 - - ---- -copper mordant, 167 - - ---- -formaldehyde tan, 64 - - ---- tans, 57, 174 - - Chromium mordants, 120, 166 - - ---- ---- alkaline, 123 - - ---- salts in tanning, 53 - - Cleaning pelts, 40 - - Coal tar colors, 171 - - Cocoanut oil, 60 - - Cod-liver oil, 60 - - Collagen, 25 - - Colloidal solutions, 48 - - Combination tans, 49, 64 - - Conveying dyed skins, 104 - - Conveyor drying, 73 - - Copper acetate, 119 - - ---- mordants, 119, 166 - - ---- salts, 109 - - ---- ---- after-treatment with, 168 - - ---- sulphate, 119 - - Copperas, 119 - - Copper-iron mordant, 167 - - Coriin, 21 - - Corium, 21 - - Cortex, 23 - - Cottonseed oil, 60, 63 - - Cuba wood, 134 - - Cutch, gambier, 65, 135 - - Cuticle, 23 - - - Davy, Sir Humphrey, 47 - - Degreasing furs, 179 - - Diphenyl black, 152 - - Dip process, 98 - - Dressing of lambs, 52 - - ---- ---- rabbits, 54 - - ---- ---- moles, 54 - - Drum, 80 - - Drum-cleaning, 105 - - Drumming, 76 - - Drying-oils, 60 - - Drying skins, 71 - - Durability of furs, 5 - - Dyeing furs at higher temperatures, 174 - - Dyeing of imitations, 93 - - ---- ---- novelty shades, 92 - - ---- with aniline black, 144 - - ---- ---- coal tar colors, 171 - - ---- ---- mineral colors, 125 - - ---- ---- oxidation colors, 155 - - ---- ---- vegetable colors, 128 - - - Egg-yolk, 63 - - Emeraldine, 145 - - Enzymes, 51 - - Epidermis, 21 - - Erdmann, 155 - - Ermine, 5, 9 - - ---- bleaching of, 179 - - - Fahrion, 48 - - Fat-glands, 21 - - Fats, animal, 59 - - Fermentation, 51 - - Ferrous acetate, 119 - - Ferrous sulphate, 119 - - Finishing dyed furs, 104 - - Fisher, 9 - - Fitch, 9, 94 - - Flat skins, 36 - - Fleshing, 41 - - ---- knife, 38, 42 - - ---- machines, 42 - - Flesh side, 22, 37 - - Formaldehyde, 63 - - ---- -chrome tan, 64 - - ---- tans, 49, 63 - - Formic acid, 44, 50 - - ---- ---- as soaking agent, 39 - - Fox, black on, 140 - - ---- blue, 9 - - ---- cross, 4, 10 - - ---- grey, 10 - - ---- kit, 10 - - ---- red, 4, 5, 10 - - ---- ---- dyed imitation silver fox, 137 - - ---- silver, 4, 10 - - ---- ---- imitations, 137, 143 - - ---- white, 11, 94 - - ---- ---- bleaching of, 179 - - French seal dye, 138, 144 - - Furamine dyes, 162 - - Fur beating machine, 80 - - Fur dressing, 30 - - Fur dyeing, 91 - - ---- ---- difficulties of, 95 - - ---- ---- with aniline black, 144 - - ---- ---- with coal tar colors, 171 - - ---- ---- with mineral colors, 125 - - ---- ---- with oxidation colors, 155 - - ---- ---- with vegetable colors, 128 - - Fur-hair, 24 - - Furriers' guilds, 34, 90 - - Furrol dyes, 166 - - Furs, colors of, 3 - - ---- description of, 7 - - ---- durability of, 5 - - ---- of carnivorous animals, 37 - - ---- of herbivorous animals, 37 - - ---- quality of, 3, 4 - - ---- uses of, 1 - - ---- valuation of, 6 - - ---- weight of, 5 - - Fustic, 134 - - ---- shades with, 135 - - - Gall-nuts, 128, 132 - - Gambier cutch, 65, 135 - - Gelatine, 1, 25, 47, 48 - - Genet, 5 - - Glycerine, 63 - - Goat, 5, 11 - - ---- logwood black on, 141 - - Green's process for aniline black, 152 - - Grey-blue on white furs, 142 - - Ground water, 87 - - Guard-hair, 24 - - Guilds, furriers', 34, 90 - - - Hair, 22 - - ---- action of acids on, 27 - - ---- action of alkalies on, 28 - - ---- action of salts on, 28 - - Hamster, 3, 11 - - Hardness of water, 87 - - Hare, 5, 11, 94 - - ---- black on, 140 - - ---- blue-grey on, 142 - - ---- lynx dye on, 126 - - ---- stone marten imitation on, 126 - - Hematein, 133 - - Hematoxylin, 133 - - Herbivorous animals, furs of, 37 - - Hudson seal, 144 - - Hydro-extraction, 40 - - Hydrogen peroxide, 168 - - ---- ---- bleaching with, 182 - - Hydrosulphite bleach, 181 - - Hypochlorites, 184 - - - Imitations, dyeing of, 93 - - Iron mordants, 119, 167 - - Iron pyrolignite, 119 - - Iron salts in tanning, 53 - - Iron tan, 58 - - Iron vitriol, 119 - - - Kangaroo, 12 - - Keratin, 25 - - Kicker, 61 - - Killing, 98, 106 - - ---- formulas, 108 - - ---- nature of, 107 - - ---- purpose of, 106 - - ---- by brush process, 111 - - ---- by dip process, 111 - - ---- with caustic soda, 113 - - ---- with lime, 112 - - ---- with soda, 112 - - Knapp, 46, 57 - - Knife, beaming, 38 - - ---- shaving, 38 - - ---- fleshing, 38 - - Kolinsky, 5, 12 - - Krimmer, 5, 12, 13 - - - Lactic acid, 44, 51 - - Lactic acid fermentation, 50 - - Lambs, 12 - - ---- dressing of, 50, 53 - - ---- dyeing of, 92, 140, 141, 142 - - Lard, 60 - - Lead, acetate, 126 - - Lead sulphide dye, 126 - - Leather, definition of, 48 - - ---- dressing of, 30 - - Leopard, 5, 13, 94 - - ---- tanning of, 43 - - Lima wood, 135 - - Lime, 108, 110, 112 - - Linseed oil, 60 - - Litharge, 109 - - Loft drying, 72 - - Logwood, 133 - - ---- blacks, 139 - - ---- shades with, 134 - - Lynx, 5, 13 - - ---- imitation on rabbit and hare, 126 - - Luster of hair, 23 - - - Machines used in brush dyeing, 102 - - ---- ---- dip dyeing, 103 - - Marmot, 14, 68, 94 - - Marten, blending of, 91, 104 - - Marten, baum, 5, 14 - - ---- stone, 5, 14 - - ---- ---- imitation, 126 - - Medulla, 22 - - Meunier, 46 - - Mineral colors, 125 - - ---- oils, 59, 63 - - ---- tans, 49, 53 - - Mink, 5, 14, 68, 94 - - Mole, 5, 15 - - ---- tanning of, 54 - - Monkey, 15 - - Mordanting, 98, 114 - - Mordants, alkaline, 121 - - ---- aluminum, 118 - - ---- chrome-copper, 167 - - ---- chromium, 120, 166 - - ---- copper, 119, 166 - - ---- copper-iron, 167 - - ---- iron, 119, 167 - - ---- tin, 121 - - Mucines, 25 - - Muskrat, 5, 15, 68, 94 - - ---- imitation seal on, 144, 169 - - - Neats-foot oil, 60, 63 - - Neradol D., 64 - - Nigraniline, 147 - - Non-drying oils, 60, 63 - - Novelty shades, dyeing of, 92 - - Nutgalls, 33, 132 - - Nutria, 5, 15, 94 - - - Oiling, 62, 77 - - Oils, drying, 60 - - ---- non-drying, 50 - - ---- partially-drying, 60, 63 - - Olive oil, 60 - - One-bath aniline black, 149 - - Opossum, 5, 15, 68 - - ---- black on, 140 - - ---- skunk imitation on, 138 - - ---- seal imitation on, 144 - - Otter, River, 5, 16, 94 - - ---- Sea, 5, 16 - - Over-hair, 24 - - Oxidation aniline black, 150 - - ---- colors, 155 - - ---- ---- shades with, 165 - - - Para-amido phenol, 153, 157 - - Para-phenylene diamine, 153, 157, 162 - - Partially-drying oils, 60, 63 - - Pelage, 2 - - Pelt, 2 - - Pernambuco wood, 135 - - Peroxide of hydrogen, 168, 182 - - Peroxides, 182 - - Persian lamb, 5, 12 - - ---- ---- dressing of, 50, 53 - - ---- ---- dyeing of, 139 - - Physical theories of tanning, 47 - - Pickle, 49 - - Pigment granules, 23 - - Pony, Russian, 5, 16 - - Potassium permanganate as a dye, 127 - - ---- ---- as a bleach, 183 - - Protective-hair, 24 - - Pyrolignite of iron, 119 - - - Quercitron, 135 - - Quinone di-imine, 163 - - - Rabbit, 6, 17, 94 - - ---- imitation seal on, 144 - - ---- lynx imitation on, 126 - - ---- sable imitation on, 168 - - ---- stone marten imitation on, 126 - - ---- tanning of, 54, 65 - - Raccoon, 6, 17 - - ---- black on, 140 - - ---- skunk imitation on, 170 - - Rain water, 86 - - Red fox, dyed as silver fox, 137 - - Redwood, 135 - - Rodol colors, 165 - - Russian tan, 51 - - - Sable, 6, 94 - - ---- American, 17 - - ---- blending of, 91, 104 - - ---- imitation on rabbit, 168 - - ---- Russian, 18 - - Salammoniac, 109 - - Salt, 32, 49 - - ---- -acid tan, 49 - - ---- -water soak, 39 - - Salts, neutral, 54 - - ---- basic, 54, 115 - - Sawdust in drum-cleaning, 80 - - "Schrot-beize," 50 - - Seal, 6, 18, 94 - - ---- fur, 18 - - ---- dyeing of, 92, 144 - - ---- hair, 19 - - ---- imitation on muskrat, 138, 169 - - ---- -oil, 60 - - Shearing, 82 - - ---- machine, 84 - - Shrinking-point of skins, 66 - - ---- effect of chemicals on, 67 - - Silver fox imitations, 137, 143 - - Skin, 21 - - ---- action of acids on, 26 - - ---- action of alkalies on, 27 - - Skunk, 6, 19, 94 - - ---- imitation on opossum, 138 - - ---- ---- on raccoon, 170 - - Soaking skins, 39 - - Soda ash, 110, 112 - - Sodium bichromate, 121, 166 - - ---- bisulphite, 127, 181 - - ---- chloride, 49 - - ---- peroxide, 182 - - ---- sulphite, 181 - - Soft water, 87 - - Softening skins, 38 - - Souring, 113 - - Squirrel, 6, 19 - - Staking, 78 - - Stannous chloride, 121 - - Stiasny, 64 - - Stone marten imitation, 126 - - Stretching, 78 - - ---- machines, 78 - - Sugar of lead, 126 - - Sulphonated oils, 63 - - Sulphuric acid, 49 - - Sulphurous acid bleach, 180 - - Sumach, 128, 133 - - ---- tanning with, 33 - - Surface water, 87 - - Sweat-glands, 22 - - - Tallow, 60 - - Tanned furs, qualities of, 48 - - Tanning methods, comparison of, 65 - - Tannins, 32, 132 - - Tiger, 19 - - Top-hair, 24 - - Train oils, 63 - - Tramping machine, 61 - - Turmeric, 136 - - - Under-hair, 24 - - Under-wool, 24 - - Ungreenable aniline black, 148 - - Unhairing, 82 - - ---- machine, 83 - - Ursol dyes, 157, 165 - - - Vanadium compounds, 147 - - Vat dyes, 177 - - Vegetable dyes, 128, 136 - - ---- oils, 59 - - ---- tans, 49, 65 - - Verdigris, 120 - - - Water, hard, 87 - - ---- soft, 87 - - Whale oil, 60 - - White fox, bleaching of, 179 - - Wolf, 6, 19 - - Wolverine, 6, 20 - - Wombat, 20 - - Wood dyes, 128 - - - Yellow wood, 134 - - - - -LITERATURE OF THE CHEMICAL INDUSTRIES - - -On our shelves is the most complete stock of technical, industrial, -engineering and scientific books in the United States. The technical -literature of every trade is well represented, as is also the literature -relating to the various sciences, both the books useful for reference as -well as those fitted for students' use as textbooks. - -A large number of these we publish and for an ever increasing number we -are the sole agents. - - ALL INQUIRIES MADE OF US ARE CHEERFULLY AND - CAREFULLY ANSWERED AND COMPLETE CATALOGS AS - WELL AS SPECIAL LISTS SENT FREE ON REQUEST - -[Illustration] - - - D. VAN NOSTRAND COMPANY - - _Publishers and Booksellers_ - - 8 WARREN STREET NEW YORK - - - * * * * * - - -Transcriber's Notes: - -Punctuation has been standardised--in particular, missing periods -and quotation marks have been supplied where obviously required. -Three entries in the bibliography were located out of alphabetical -order, and have been moved accordingly (Fougerat, Lamb, Martin). -All other original errors and inconsistencies have been retained, -except as follows: - - Page 7: changed Enclyclopedia to Encyclopedia - (in Encyclopedia Britannica, 11th Ed.) - Page 20: changed Kaola to Koala - (Koala or Australian Bear.) - Page 62: changed partiular to particular - (on the particular fur treatment) - Page 67: changed degress to degrees - (almost 10 degrees higher than) - Page 73: changed samewhat to somewhat - (based on a somewhat different) - Page 93: changed imitatations to imitations - (dyeing of imitations to a great) - Page 101: changed diagramatically to diagrammatically - (and B shows diagrammatically, machines) - Page 128: changed conjuction to conjunction - (which in conjunction with certain) - Page 136: changed curcuma to Curcuma - (stem of the Curcuma tinctoria,) - Page 137: changed simutaneously to simultaneously - (and dye simultaneously; and third) - Page 140: changed atmopheric to atmospheric - (aid of the atmospheric oxygen.) - Page 142: changed followlowing to following - (successively in the following baths:) - Page 149: changed ozidizing to oxidizing - (is also an oxidizing agent and) - Page 154: changed dryig to drying - (several times, drying each time at) - Page 161: changed manufacurers to manufacturers - (Other manufacturers of coal-tar) - Page 170: changed Racoon to Raccoon - (_Imitation Skunk on Raccoon_) - Page 185: changed Werkstatte to Werkstätte - (Halle "Werkstätte der heutigen) - Page 185: changed Gerben to Gerbens - (Geschichte des Gerbens und der) - Page 185: changed Astringentien to Adstringentien - (und der Adstringentien" 1917) - - - - - -End of the Project Gutenberg EBook of Principles and Practice of Fur -Dressing and Fur Dyeing, by William E. 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