Principles and Practice of Fur Dressing and Fur Dyeing Part 2

~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 j.a.pan. 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 coa.r.s.e, 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 const.i.tutes 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 princ.i.p.al 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 a.n.a.logous to the h.o.r.n.y 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 h.o.r.n.y 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 pa.s.s 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 h.o.r.n.y, almost h.o.m.ogeneous, transparent ma.s.s, 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.

[Ill.u.s.tration: 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 l.u.s.tre or gloss of the hair depends. Since l.u.s.tre 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 l.u.s.tre. 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 coa.r.s.er 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 const.i.tutes 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 ill.u.s.trate these differences. In each case, the two large hairs on the left of the ill.u.s.tration 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 cla.s.s 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 const.i.tutions, but all show, on a.n.a.lysis the following approximate composition of chemical elements:

Carbon 5055% Hydrogen 6.57.3% Nitrogen 1517.6% Oxygen 1924% Sulphur 0.35%

The princ.i.p.al kinds of proteins found in the various fur structures are alb.u.mins, keratin, collagen, and mucines. Alb.u.mins, 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.

[Ill.u.s.tration: 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 h.o.r.n.y parts of the animal body are composed, such as the hair, nails or hoofs. It is the princ.i.p.al const.i.tuent 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 princ.i.p.al 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, h.o.r.n.y and translucent. The mucines are also const.i.tuents 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 cla.s.ses 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 quant.i.ties 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 pota.s.sium 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 quant.i.ties. From a dilute solution of alum, aluminum hydroxide is absorbed by the hair, the pota.s.sium sulphate remaining in solution. Similarly with copper, iron, and chromium salts, the metal oxides are fixed by the fibre.