YARN. The derivation of this word from "garn," a word com mon to the Scandinavian languages, meaning "guts," is interesting since today "cat-gut," which may be the drawn-out "guts" of the silk-worm, is a well-known commodity ; and the same "guts" spun by the silk-worm itself into a fine filament are the basis of the best silk yarn produced. The silk-worm, however, in its "spinning" simply thins-out the silk fluid to a double microscopic strand some 500 to I,000 yards long, several of which are com bined by mechanical means to form a yarn; while the human spinner usually combines a number of much shorter fibres or filaments, also by mechanical means, into a continuous strand often much longer than the T,000 yards filament of the silk-worm; and this also is spoken of as a yarn.
Materials.—The materials from which yarns are constructed or spun markedly influence the processes of production. In the case of the best silk yarn the worm itself does what is termed the spinning and the later running-together of several of the long silk filaments is not spoken of as spinning but as "throwing." In the case of a typical short fibre—say the cotton fibre long—the spinning process is the binding together of many thou sands of cotton fibres into a fine regular, continuous thread— usually spoken of as "yarn." Two or more of these threads or single yarns may be combined together by "twisting" to produce a thicker, stronger yarn. Of the true long fibres there are only two types, the natural silk reeled from the cultivated silk-cocoon and the synthetic artificial silks.
Of the short fibres there are many classes. The longest are the waste silks just mentioned; then come the animal fibres includ ing hairs and wools up to 18" long, short wools down to, say, 2" long and broken-up wool fibres (variously termed shoddy, mungo, extract, flocks, etc., according to their source and manner of breaking up from the virgin wool clothes, knitted garments, etc.) which (it is popularly said) can be spun into yarn if they possess two ends ; next come the "stem-fibres" such as flax (pro ducing linen yarn), hemp, jute and china-grass which may vary in length f tom several inches down to fractions of an inch ; lastly come the cotton fibres and cotton wastes often under one inch in length along with which should perhaps be ranked the mineral fibre asbestos, which may be spun into a yarn from which fire proof cloths are woven.
Structures.—Yarn structures may be considered from two points of view. In the first case particular fibres lend themselves only to particular "fibre combinations." Thus long silk filaments can only be "thrown" together with or without "twist." But the twisting of silk filaments is an art in itself. Thus several filaments may be reeled together from separate cocoons and these given a suitable "combining-twist" to produce what is known as singles; then several of these singles may be thrown together with little twist to produce almost a "paralleled-fibre" thread termed "tram" the most lustrous yarn known, or with much twist to produce a strong, fairly lustrous yarn termed "organzine" which is employed as "warp." On the other hand one inch cotton fibres after being drawn into a fairly fine "paralleled sliver" termed a "roving" can only be spun out into a fine thread by means of "supporting twist" which no doubt binds the fibres more or less concentrically in the thread or yarn : this is said to be the true form of spinning— draft (that is, drawing-out thinner) against twist.
Fancy Twists.—These naturally group themselves into three classes, viz., structural twists ; colour twists ; and structural-and colour twists. Of the first class the two most important are the knop yarn—in which knops are formed at any required intervals on an otherwise level thread by holding one thread tightly and allowing the second thread to run in slackly to form knops of the required size, after which equal delivery of the two threads for the required length is followed again by the varied delivery to form the knop; and the curl yarn—in which a knop yarn is first formed and then this two-fold yarn twisted, in the opposite direc tion, with a third thread, this opening out the knops into loops which may be produced at more or less regular intervals or "spaced," i.e., a length of the thread without loops and then a series of loops, which in turn are followed by a length of the thread without loops. Of fancy colour twists the simplest is the cork screw twist which is formed by first twisting, say, a dark and a light thread in the normal manner and then twisting this two-fold yarn in the reverse direction, with a third dark thread, this produc ing the special appearance which gives its name to the yarn.