Silk Manufacture

SILK MANUFACTURE. In discussing silk manufacture, it is necessary to distinguish between the preparation of the silk cocoons through the process called reeling and the manufacture of products made from the threads wound from the cocoons in that process. Both are referred to as silk manufacture although the term popularly refers to the fabricated products rather than to the thread which is termed raw silk. There is still another exception; the waste or by-product of the cocoons is shipped to the silk man ufacturing countries for spinning into a special yarn termed spun silk. The process used resembles _cotton or wool spinning methods rather than silk reeling. The silk thread commonly used is raw silk and for that reason silk yarn for industrial use can be con sidered as raw silk, not spun silk, unless otherwise specified.

Filature or Reeling.

When the cocoons have been gathered and the chrysalides they contain have been stifled, they are sorted into qualities for reeling. Doubles (cocoons made by two worms in conjunction), pierced cocoons and any from other causes rendered unreelable are put aside for the spun silk manufacture. During the gathering from the rearers of "fresh" cocoons, i.e., while the chrysalides are alive, a certain amount of crushing oc curs, which smashes the chrysalis and naturally saturates the co coon with its fluid. One cocoon thus crushed may be the cause of staining several others. Also, there are partly reelable cocoons made by unhealthy worms. A black fluid is exuded from some of these cocoons, which, in turn, stain all the cocoons in their vicinity. Worms which have been ill fed make cocoons of a weak thread. The sorting is done by hand, and the cocoons separated into four qualities, (a) cocoons which are perfectly clean and firm, (b) cocoons which are otherwise good but which have been stained by crushed cocoons, (c) weak cocoons and (d) cocoons crushed and badly stained from within. The (c) and (d) qualities, which form but a small proportion of the whole, are reeled as quickly as possible, for they are liable, if kept in store, to attack from an insect fly which bores a minute hole about the size of a pinhead through them and renders them unsuitable for reeling. The (b) quality, which forms about 20% of the whole, is also susceptible to the insect, but to a much smaller degree, so these are worked next, leaving the (a) quality for the remainder of the year's work. This assortment is of great consequence for the success of the reeling operations, as uni formity of quality and evenness and regularity of fibre are the most valuable features in raw silk. The object of reeling is to bring together the filaments (Fr. bave) from two or more (gen erally five or six, but sometimes up to 2o) cocoons, and to form them into one continuous, uniform and regular strand, which constitutes the "raw silk" of commerce. To do this, the natural gum of the cocoons which holds the filaments together must be softened, the ends of the filaments must be caught, and means must be taken to unwind and lay these filaments together, so as to form a simple uniform rounded strand of raw silk. This reeling process is generally carried out by female labour; it is extremely delicate but by no means hard work. The establishment in which it is done is called a filature, and may consist of anything from 20 to 30o reeling basins. Each reeler is issued with a given weight of cocoons, and the worker who prepares them for the reeler places a quantity of them in a round, deep basin with water kept at a certain level automatically and heated to boiling point by a steam coil in the bottom. A circular bass broom made to fit exactly over the basin is shut down on the soaking cocoons (which float on the surface of the water) so that the ends of the bass just touch the tops of the cocoons. The broom is set to work in a circular motion first one way and then the other by machinery until the ends of the broom have caught the outside fluff and the actual filament (maitre brin) is found. The worker pulls up the broom, disengages the hank of fluff from the bass from which now depends the filament of each cocoon separately.

She catches up the cocoons from the water by means of a strainer and passes it over to the reeler. The latter empties the cocoons into her basin, which also contains water kept at a level automatically and heated by a steam coil to 180° to 200° F. She then "makes her threads." Filatures are constructed to enable four, six and eight skeins to be reeled by one reeler at a time. The reeler takes the fila ments of, say, six cocoons and makes one thread of them by twisting them together ; this combined thread is passed through an apparatus about tin. above the water level, upwards about i8in. round a tiny glass conducting reel, then downwards round a similar glass reel and upwards again until the thread crosses itself. Here it is twisted round itself many times and is then taken through a glass conducting hook above the reeler's head, passed through a porcelain slit and finally attached to the reel on which the skein is to be wound. The process is repeated until the four, six or eight threads, each consitting of the threads of six cocoons, are attached to the reels. The reels are set re volving by means of a control lever ready at the reeler's hand, and as the reels revolve, they pull the threads; if eight skeins are being reeled, the 48 cocoons which go to make the eight threads all begin to turn about in the water as they unwind themselves in response to the pulling of the reels. When each thread is in motion, it travels through the apparatus with a minute hole, which prevents to a great extent any imperfection in the thread getting through, then through the twist on itself, then round the two glass conducting reels, then through the twist on itself for the second time and thence to the porcelain slit just in front of the reel, and finally on to the reel itself. The porcelain slit has a short cross motion of about I lin. which spreads the skein evenly over the surface of the reel. The twist on itself given to the thread is most important for it performs two functions; it rounds, smooths and condenses the six separate filaments into one strand, and as the surface of the filaments is gummy and adhesive, the threads are agglutinated into a compact single fibre of raw silk. The twist also expels from the thread all the moisture on it from the water in the basin in the form of spray and it reaches the reel practically dry. A silk thread made up of the filaments of six cocoons is scarcely visible, and yet it can easily stand the strain imposed on it by this twist on itself which is as long as six inches. A good silk should stretch about one-third of its own length before reaching breaking point. Dur ing the reeling process, the cocoons, of course, give off all their silk in a short time and breaks continually occur, so the reeler has to watch the unwinding cocoons carefully and directly she detects a cocoon that is motionless, she supplies the thread of another from a reserve which she keeps ready. The apparatus through which the thread is originally passed has a little disk attached to it which revolves rapidly. The reeler places the filament of the new cocoon across her extended first and second fingers, she advances her fingers to the disk, one above and one below, the disk cuts the filament and whirls it round the others which absorb it, and the new cocoon begins unwinding. A break of one filament in a thread of six will be rectified by a first-class reeler before half a yard of thread has gone through. An unheed ed break means a thin spot in the completed thread—the result shows as a "ring" or uneven shading in hosiery or fabric. All co coons whose filaments break before they are finished are re turned to have their filaments found again by a second brushing. As soon as the cocoons issued to the reeler are finished, the silk is removed from the reels and taken to the silk room. It is weighed and a ratio to the quantity of cocoons used is found.