Page:EB1911 - Volume 28.djvu/836

Rh series of three burring rollers rotating in an opposite direction, the projecting rails of which knock the burrs off the wool. The burrs fall on a grating and are ejected, with a certain amount of wool adhering to them, by another rotating cylinder. With wools not too burry the worsted spinner largely depends upon burring rollers placed upon the first cylinder of the “carder,” and possibly to one or other of the patent pulverizing processes applied further on in the card. In the latter process a complete pulverizing of the burrs is aimed at this being effected by the introduction of specially constructed pulverizing rollers between the first doffer and the last swift of the carding engine.

The processes hitherto described are common to merino, cross-bred or botany wools be they intended for woollen or worsted yarns.

From this point, however, differentiation starts. Wool may now be manipulated with the idea of converting it into (q.v.), woollen or worsted fabrics. In a general way it may be said that woollen yarns are those made from short wools possessed of high felting qualities, which are prepared by the process of carding; whereby the fibres are as far as possible crossed and interlaced with each other, and that the carded-slivers, though perhaps hard spun on the mule frame, form a light fluffy yarn, which suits the conditions when woven into cloth for being brought into the semi-felted condition by milling which is the distinguishing characteristic of woollen cloth. On the other hand, worsted yarns are generally made from the long lustrous varieties of wool; the fibres are so combed as to bring them as far as possible parallel to each other; the spinning is usually effected on the frame, and the yarn is spun into a compact, smooth and level thread, which, when woven into cloth, is not necessarily milled or felted. At all points, however, woollen and worsted yarns as thus defined overlap each other, some woollens being made from longer wool than certain worsteds, and some worsteds made from short staple wool, carded as well as combed. Worsted yarn is now largely spun on the mule frame, while milling or felting is a process done in all degrees—woollen being sometimes not at all milled, while to some worsteds a certain milled finish is given. The fundamental distinction between the two rests in the crossing and interlacing of the fibres in preparing woollen yarn—an operation confined to this alone among all textiles, while for worsted yarn the fibres are treated, as in the case of all other textile materials, by processes designed to bring them into a smooth parallel relationship to each other.

To obtain a sliver which can be satisfactorily spun into a typical woollen thread

following operations are necessary: willowing, oiling and blending, teasing, carding (two or three operations), condensing and roving. Spinning upon the woollen mule completes the series of operations all of which are designed to lead up to the desired result. Of the foregoing operations the carding is perhaps the most important as it is certainly one of the most interesting. At the same time it must be fully realized that deficiencies in any one of these operations will result in bad work at every subsequent process. For example, let an unsatisfactory combination of materials be blended together and there will be trouble in both carding and spinning. The roving operation included above is not always necessary. In the old days, if a really fine thread were required, roving was absolutely necessary, as the carder could not turn off a sliver fine enough to be spun at one operation. To-day, however, with the “tape” condensers, such fine slivers can be turned off the condenser that there is no difficulty in spinning directly to the required count. In some few cases, however, it may be cheaper to rove than to condense fine; again, certain physical characteristics appertain to the roved thread, as distinct from the condensed thread, which may occasionally be of use to the cloth constructor.

At the beginning of the 19th century woollen cloths were made of wool—some of them of the very finest wool obtainable. Today

woollen cloths are made from any and every kind of material, of which the following are the most important: noils (botany, cross-bred, English, alpaca and mohair), mungo, shoddy, extract, flocks, fud (short mill waste), cotton sweeping, silk waste, &c., &c.; in fact it is said that anything which has two ends to it can be incorporated into a woollen thread and cloth. It does not follow, however, that all woollen cloth is cheap and nasty. On the contrary the west of England still produces the finest woollen fabrics of really marvellous texture and beauty, and Batley, Dewsbury, &c., produce many fabrics which are certainly cheap and yet anything but nasty. The first essential for blending is that the materials to be blended should be fairly finely divided. This is effected by passing each material, if necessary, through the willow or through the “fearnaught”—a machine coming between the willow and card—prior to beginning the “blend-stack.” Sometimes it may be that a blending of different colours of wools to obtain a definite “colour mixture” is necessary, more often it will

be a blending of various materials, such as noils, mungo, cotton, &c., to obtain a cheap blend which may be spun into a satisfactory warp or weft yarn. The blender proceeds as follows first a layer of No. 1 material—say wool—is spread over the required area on the floor; it is then lightly oiled. A layer of No. 2 material—say noils—is now added to the first layer; then another layer of wool with rather more oiling; then No. 2, then No. 1 with still more oil until all the material is built up into layers in the stack. The stack is now beaten down sideways with sticks, and then the more or less mixed mass is passed through the willow and fearnaught still further to mix it prior to carding, where the true and really fine mixing takes place After passing through the fearnaught the material is sheeted and left to “mellow,” this no doubt consisting in the oil applied distributing itself throughout the material. If wool and cotton are blended together the wool must be oiled first, or the blend will not work to the greatest advantage. The oil may be best Gallipoli olive oil—which should not turn rancid—but there are many good oils—and unfortunately many bad oils—placed on the market at a reasonable rate which the really skilled judge may use to advantage. The percentage of oil varies from 2% to 10%—this remark applies both to the woollen and worsted trades—and there is no guide as to the amount required, saving and excepting experience, observation and common sense. Automatic oiling arrangements have been applied in the woollen trade with only a moderate amount of success, the sprinkling of the oil by means of a watering-can on the stack, made as described above, still being most in favour. The oil serves to lubricate the fibres, and to render them more plastic and consequently more workable, and to bind the fibrous mass together and thus prevent “fly” during the passage through the cards.

Fig. 8.—Sectional View of Carder; illustrating the principles of carding.

Carding was originally effected by hand, two flat boards with convenient handles, covered with teeth or card clothing, serving as a means of teasing out lock by lock, fibre by fibre, reversing root to tip

and tip to root, so that a perfect mixing of the fibres resulted. It was but natural that, when an attempt was made to render the carding operation more mechanical, the operation should be converted into a continuous one through the adoption of rollers in place of flats. Flats combined with rollers still maintain their position in cotton carding, but in wool carding the pure roller card is employed. The factors of carding are size of rollers, speeds of rollers, inclination of teeth and density of card clothing. Probably no operation in the textile industries is so little understood as carding. Thus the long wool carder would think a man an idiot who suggested the running of the teeth of the various cylinders actually into one another, while the short mungo carder regularly carries out this idea, and so on. The underlying principle of carding, however, is shown in fig. 8, in which a sectional drawing of part of a card is given. The wool is carried into the machine on a travelling lattice and delivered to the feed rollers A, A′, A″ of which A and A″ in turn are stripped by the licker-in B working at a greater speed point to smooth side. This in turn is stripped by the angle stripper C again working at a greater speed point to smooth side, which in its turn is stripped by the swift D—the “carrying-forward” and swiftest carding cylinder in the machine. The swift carries the wool forward past the stripper E—which as a matter of fact is stripped by the swift still working point to smooth side—into the slowly retreating teeth of the first worker F, which, being set a fair distance from the swift, just allows well laid-down wool to pass, but catches any projecting and uncarded staples. The worker in its turn is stripped by the stripper E′, which in turn is stripped by the swift as already described. The passage of the wool forward through the machine depends upon its being carried past each worker in turn. Thus from beginning to end of a machine the workers are set closer and closer to the swift, so that the last worker only allows completely carded wool to pass it. Immediately on passing the last worker F′ the wool is brushed up on the surface of the swift by the “fancy” G—as a rule the only cylinder whose teeth actually work into the teeth of the swift and the only cylinder with a greater surface speed than the swift. The swift then throws its brushed-up