WOOL (AS. wull, wul, Goth. wulla, OHG. wolla, Ger. Wolle, wool; connected with Lat. villus, vellus, OChurch Slav. vlŭna, Lith. vìlna, Skt. ūrnā, wool, from var, to cover). The soft hairy covering of sheep and several allied animals, next to cotton the most extensively used of all fibres. Its history dates back to the earliest times of which we have any record, and as civilization has progressed its uses and applications have steadily increased.
Wool Production and Consumption. The chief wool-producing countries of the world are: Argentina, Uruguay, and other South American countries; Australia and New Zealand; the United States; Russia, Great Britain and Ireland, France, Spain; South Africa; and India. The world's clip for 1900 was estimated by the National Association of Wool Manufacturers at 2,685,000,000 pounds. The consumption of wool in the United States has always been relatively large. Prior to the beginning of the factory era it did not average more than three pounds per capita of population annually, and in the middle of the last century it amounted to four pounds, but as wealth increased and the uses of wool enlarged, the consumption increased to about eight pounds per capita in 1900. In that year the wool clip of the United States was estimated at 290,000,000 pounds, the product of 40,000,000 sheep. About two-thirds of the wool then used by American mills was supplied by domestic flocks. The imported wools largely used for blankets and carpets are mostly of lower quality. The principal wool-producing States are Montana, New Mexico, Ohio, Texas, Wyoming, Colorado, Oregon, Idaho, California, Utah, Michigan, and Arizona.
Sheep-raising has preceded civilization in nearly all parts of the world. Before agriculture was practiced to any extent, it was almost universal. With the progress of civilization, the use of wool for making cloth led to the improvement of the fleece by selection and breeding. The Romans greatly increased the fineness of the fleece, and after the Roman conquest of the Iberian Peninsula Roman sheep were introduced into Spain, where they so greatly improved the native flocks that even during Roman supremacy Spanish wool led in the world's markets, a prestige held for many centuries. Through judicious crossing of the fine-wooled Merino with high-grade long-wooled breeds, the highest type of wool fibre has been developed, combining suppleness, fineness, and other desirable qualities with lustre and length of staple. It is suitable for combing as well as carding.
Wool may be considered a product of cultivation, or domestication, as no wild animals are known which resemble the wool-bearing sheep; and few natural products have been more modified and diversified by man to meet his various needs. This is very strikingly shown by a comparison of the coarse heavy covering of the argali or musmon (the supposed progenitors of the sheep), with the fine wool of the Merino or the long, lustrous fleece of the Leicester. These animals were covered with coarse hair or fur. among which close to the skin was a softer hair or wool. Under the influence of good care and feed, and protection from the inclemencies of the weather, the longer coarse hair largely disappeared, and only the softer, shorter hair or wool remained, a phenomenon said to be observed when the argali is brought under domestication.
Characteristics and Properties of Wool. Wool is a living appendage of the skin, produced by increased epidermal cells. The difference between wool and hair is one of degree rather than of kind, because all wool-bearing animals have the tendency when neglected to produce hair rather than wool, and because numerous intermediate structural stages exist between the two extremes. While wool is commonly characterized by its fine, soft, curly nature, the true distinction between it and hair lies in its covering of pointed scales or plates, attached to the filament at their bases and overlapping much like fish-scales. This structure, which is readily seen with a microscope, is perceptible to the touch by its harsh, rough feeling when the fibre is drawn through the fingers from the tip to the root. The number of these scales bears a fairly direct relation to fineness of the fibre. The curliness of wool is due to a spiral structure of the filaments, and although all wool is not curly or wavy, curliness is one of its recognized and important characteristics. There also appears to be a relation between fineness and curliness. Owing to the relation which these three characteristics bear to each other, curliness, or the number of waves to the inch, which can be seen with the naked eye, is one of the factors noted in judging of wool. The waviness and sealiness are utilized in making felt (q.v.) and also in thread-making. A pound of the finest wool will yield nearly 100 miles of thread. In spinning, the filaments interlock by their scales, and the curl of the fibre prevents the threads untwisting and helps to hold them together. These valuable qualities vary greatly in different wools, some being adapted to carding for cloth, and others to combing for worsteds. It is upon minute points of difference that the value of various grades of wool chiefly depends. The lustre also differs greatly and to a certain extent is a breed characteristic, the wool of the Lincoln and the best Leicester sheep being much more lustrous than that of the shorter wools or the fine Merino fleece. The length of staple, which is made a basis of general classification, is largely a constitutional or breed characteristic, the staple being from one to two inches long in the finest Merinos, eight inches or more in the Lincolns, and reaching twelve and even fifteen inches in some combing wools, the length of staple suggesting the grouping of sheep into short-wools, middle-wools, and long-wools. The fine felting wools have a short staple, as a rule, and are used for carding or yarn purposes, while the longer, more lustrous, and less wavy ones are better suited to combing and worsteds.
Another valuable characteristic of wool is its elasticity, which gives it a softness to the touch which is retained in the manufactured goods. Closely related to this is the strength of fibre; a dead or inferior wool will break instead of stretching when strained. Delicate machines have been constructed for testing the strength and elasticity of fibre, for both practical and scientific purposes. Bowman found that wool fibre is fully one-fourth stronger than cotton, the strength being proportional to the diameter. Great variation, however, exists in the strength of fibres from different wools of the same class of sheep.
All wool in its natural state contains fatty or greasy matter called yolk or suint, secreted by the skin and covering the individual hairs. This serves to lubricate the fibres and prevent their matting together, and also protects the fleece from injury. It differs in quantity and exact character with various breeds and is believed to render the wool soft and pliable. The fats and the potash salts which the yolk contains form a sort of natural soap. For manufacturing purposes the yolk, which is partly soluble in water, must be removed so as to increase the felting tendency and the ability of the wool to take dye. White is the most common color of cleaned sheep wool, and is generally preferred for manufacturing; but the black, fawn, cream, and gray shades produced by various breeds are utilized in their natural colors for certain kinds of clothing.
Variation in Properties. The wool from different parts of the same animal differs greatly in length of fibre, fineness, and structure. As a rule, the best is obtained from the shoulders and sides. That from the fore part is irregular and likely to be filled with burrs, while the loin wool is shorter and coarser, that on the hind quarters still more, and that from the under side of the throat and the belly is likely to be short, worn, and dirty. As the wool is finer on the shoulders, it is likewise superior in soundness of fibre, softness, curl, and evenness of length. Purity of blood, good general management, and uniform feeding tend toward greater uniformity of the fibre grown on different parts of the body, whereas a period of insufficient feeding or of ill health leaves a weaker and less healthy fibre at the point represented by it. Such wool is usually noticeably deficient in yolk. The importance of breeding, climate, and feeding is evidenced by the changes which occur in the wool when sheep of a given breed are removed from one region or district to another quite different. Coleman states that wool in certain districts of Yorkshire brings a higher price than that of other localities, the advantage being probably due to favorable conditions of soil and climate. On the other hand, the ability of man to counteract unfavorable conditions of a particular section is testified to by Lastereye (as quoted by Darwin), who cites the preservation of the Spanish Merino sheep in their utmost purity under such varying conditions as are found at the Cape of Good Hope, in the marshes of Holland, and under the rigorous climate of Sweden, and contends that “fine-wool sheep may be kept wherever industrious men and intelligent breeders exist.”
Kinds and Grades of Wool. The wool clipped from lambs, called in England ‘hog wool,’ differs from the wether wool, or subsequent clippings, in the staple being somewhat pointed, softer, and more wavy or curly. Lamb's wool is more valuable than wether's wool, and can be used for purposes to which the later clippings are not suited. Fleece wool, or that clipped from the live animals, is marketed as (1) ‘unwashed’ or ‘in the grease,’ i.e. as shorn from the sheep with the yolk and dirt adhering to it ; (2) ‘washed,’ i.e. washed on the sheep in cold water, which removes a part of the yolk and dirt; and (3) ‘scoured’ or cleaned ready for manufacture. ‘Tub washed’ includes fleece's broken and washed more or less by hand or machinery; ‘unmerchantable’ is applied to wool partially washed on the sheep's back but not sufficiently to be classed as ‘washed.’ By far the larger part of the wool produced in the United States, and especially west of the Mississippi River, is marketed ‘unwashed,’ which is generally preferred by wool-buyers. ‘Skirted’ is a term applied to certain fleeces imported into the United States, from which the head, belly, and breech wool (the inferior parts) have been removed, to avoid the full effect of the tariff. ‘Pulled wool,’ also called ‘skin wool,’ generally an inferior grade, comes from the pelts of sheep which have been slaughtered or have died from disease or exposure. The wool is loosened by application of a thin lime paste to the back of the skin, or by sweating the wet skins in piles.
The three main classes of wool on the basis of the staple are: (1) carding or clothing wools, or those of the Merino type, in which felting qualities are desired; (2) combing wools, in which length of staple is required and felting qualities not desired, used for hard-spun non-felting worsteds; and (3) miscellaneous, sometimes called carpet or blanket wools, long, strong, coarse wools, used for carpets, blankets, and coarse clothing. The clothing wools are commonly classified as picklock XXX, XX, X, picklock being an extremely fine fibre. The mass of high-grade clothing is made of the XX and X grades. The combing wools, often called Delaines, were formerly derived from the English mutton breeds, but machinery has been adapted for combing the Merino carding or felting wools, which have been lengthened by breeding and selection. The clothing wool used in the United States, aside from home production, is derived mainly from Australia, South America, and South Africa. The imported combing wool comes mainly from Great Britain, although much comes from New Zealand, Argentina, and Canada. The coarse carpet wools are the product of neglected flocks and unskilled breeding throughout the world.
In judging wool on the sheep's back, account is taken of strength of fibre, fineness, curl, thickness, and closure of the fleece. When the yolk is deficient the fibres become dry and brittle, and the fleece is likely to be injured otherwise. The waves of the curl should be uniform and numerous throughout the length of the fibre. The thickness of the fleece, depending upon the closeness of the fibres upon the skin, varies greatly with the breed, and also with the individual to some extent. A fairly thick and well-closed fleece is desirable. The closure is caused by the matting together of the ends of the fibres by the yolk. This gathers dust and forms a dirty coating, rendering the fleece impervious to dust and dirt, which would be injurious.
As a result of the tendency toward combing wools, both fine and coarse, Merino and English worsted wools now largely predominate in the domestic supply. Since all the improved breeds of the world have been introduced and acclimated in the United States, the range of grades of wool which have been successfully produced is very great. Breeding, care, and feeding have more than doubled the average weight of the fleece, the present average for all classes being about six pounds. Among well-tended flocks of mutton breeds, which produce a heavier fleece than the fine-wooled breeds, the yield amounts to 8, 10, and more pounds per head, in individual cases reaching or even 20 pounds. In most parts of the United States shearing is done in the spring; in Texas, New Mexico, Arizona, and southern California, where climatic conditions interfere to prevent evenness of fibre, it is done twice, the winter fleece being stronger and of greater value than that grown in summer. Since these clips do not work well together, their mixture reduces both qualities to a low level.
Defects of Wool. The most common defect of wool is ‘break,’ which is due to exposure, insufficient feeding, etc. In this the fibre contains weak spots which cause it to break when stretched. It destroys the value of wool for combing purposes. ‘Stripy’ wool is inelastic, harsh, and lacking in curl, and is used only to make inferior goods. It affects the fleece in the most valuable part—the sides and shoulders. ‘Toppiness’ is a sort of uneven felting of the fibres at the top of the fleece, so that the closure is not perfect. It is usually the result of uneven growth, and causes waste in carding. Felted wool is deficient in yolk, and as a result becomes matted together in bunches, causing loss in combing and carding. It is attributed usually to poor health. Broad-topped wool is a serious defect, in which the fibres split down from the top, interlace and mat so as to appear even on the surface, which is divided into broad masses called ‘tops.’ These cannot be parted without tearing. ‘Hemp’ or ‘kemp’ consists of a mixture of short, coarse white hairs and wool fibres, occurring chiefly on the parts where the wool is lightest and shortest, but may occur all through the fleece if the sheep has a tendency to produce hemp. Since the hairs do not take dye and cannot be sorted out, they lessen the value of the fleece fully one-half for the manufacture of fine grades of goods. In cloudy wool the fibres adhere throughout their length, but not so much as to be felty. This injures the wool for combing, causing waste, but is not so objectionable in carding wools.
Wool-Sorting. The differences in the quality of wool, and especially that from different parts of the fleece, render sorting a necessity. In shearing, the fleece from each sheep sticks together as a mat, and is tied up separately. In sorting, the different parts of the fleece representing separate qualities are torn off by hand. An idea of the location of the various qualities of wool is given by the accompanying diagram of a Leicester lamb's fleece, taken from Bowman's Structure of Wool Fibre. The same relative positions hold good in all kinds of fleeces.
FLEECE OF LEICESTER WOOL.
The finest and most even growth of wool is found at A, on the shoulders. In some fleeces this quality extends farther up the back (E) and toward the tail (B and F) than in others, and the quality of the wool at B is not very much inferior, although rather shorter and coarser. These two qualities would be graded in the woolen trade as picklock and prime or choice, while the wool from the portion indicated by C is frequently finer but shorter than A or B and apt to contain more irregular or colored hairs. When free from these defects C is graded as super in quality. The portions D and E shade into those on each side of them, and as they form the top of the neck and shoulder, the fibre is not as deep or close as at A or C. The portion over the loin (F) resembles B, into which it shades, and for many purposes, especially for spinning down, A, B, E, and F are frequently used together as one quality. Back of F, on the flanks, the wool becomes long and coarse, the best being found in the portions marked G. The wool at H and I is the coarsest part of the fleece, growing in large locks with long coarse hairs. It is often termed ‘breach’ wool and can only be used for very coarse yarns spinning low numbers. Beyond the extremities of I there is often a still lower quality called ‘tail’ or ‘cow-tail,’ which is coarse and hairy and can only be used for the very lowest numbers. The differences in quality of fibre from the same fleece are so great that a large number of sortings can be made, depending upon the character of the fleece and the purposes for which the wool is to be used. The names applied to the different qualities of wool vary in different localities, and even among different manufacturers, and this lack of uniform nomenclature is a source of no little confusion.
Other Wools. Although the typical wool is produced by sheep, and it is from that animal that much the larger part of the wool supply is obtained, there are several other animals which produce so-called wool for industrial purposes. Among these are several species of goats whose hair can be greatly improved by breeding and management, furnishing a long, fine, silky material from which beautiful textile fabrics are made. No cultivation, however, has yet prevented the growth of the outer hair on goats, as has been done in the case of sheep, or changed the undergrowth of fine hair into true wool. The alpaca goat, closely related to or a variety of the llama of South America, yields a fibre known as alpaca (q.v.). The Angora goat (see Goat), which yields mohair (q.v.), marks a distinct step toward true wool. The scales are less numerous than in the alpaca, but are more decided and exhibit a more definite edge. The fibres are very fine and wavy, lustrous, pure transparent white, and often 12 inches long, in some cases 18 or 20 inches. The diameter varies from 1850 to 11500 of an inch. The annual product of mohair in the United States is estimated at over 1,000,000 pounds. Closely allied to mohair is the fine cashmere wool of India, which is the product of the Cashmere goat, common in the Himalayan Mountains about Tibet. The hair is even longer than that of the Angora goat, but is not as curly. The surface of the fibres is not as brilliant as mohair, and the scales are more numerous but less distinct. Only the finest parts of the fleece are used, the yield from a single goat being rarely more than 3 or 4 ounces. Cashmere wool is said to be the most costly of all the wools. The fine soft hair of the camel approximates true wool in its structure, and should be mentioned in this connection.
Consult: Bowman, Structure of Wool Fibre (Manchester, 1885); Dodge, Sheep and Wool: A Review of the Progress of American Sheep Husbandry, United States Department of Agriculture, Report No. 66 (1900); Report of Bureau of Animal Industry, 1889-90; Rushworth, The Sheep (Buffalo, 1889); Mumford, The Production and Marketing of Wool, Michigan Agricultural Experiment Station, Bulletin 178 (1900); Stewart, Domestic Sheep: Its Culture and General Management (Chicago, 1898). See Sheep; Shoddy.