The silk thus usually comes into the hands of the manufacturer in the form of " hard " silk, as it is technically called, when in the gum previous to boiling. Before dyeing, it always undergoes this operation, which greatly changes its appearance. In the gum or natural state, it is dull, hard, and wiry, and might easily be mistaken for several other fibres. Boiling reduces its weight nearly one-third, softens it, and develops its lustre, bringing out its wonderful brilliance. It then becomes " soft silk." It is manufactured in both these states, though comparatively rarely in the former.
In dyeing, the weight of the dye-stuffs partially restores the loss caused by the removal of the gum ; but advantage is very often taken of this process to load the material heavily with chemicals, sometimes to the extent of 5-6 times the original weight. In some cases, as for instance when the silk has to be manufactured into fringes, and is required to hang heavily, this weighting is advan tageous in obtaining the effect ; but as a general rule, all weighting may safely be regarded as adulteration, and intended to cheapen the cost of production. It is certain that the chemicals used to weight it injure its strength and durability, and, in the end, enhance the cost.
Spun silk growing and the subsequent manipulation of the material in transforming it into articles of utility, it will be obvious that a considerable quantity of waste material must accu mulate. The floss-silk, or outer covering of the cocoon ; the perfect cocoons reserved for propagation, and which are pierced by the insect ; badly formed, entangled and otherwise defective ones ; the bottorns of cocoons when the usable filament has been wound off ; and the loose fibre produced in after stages of working, all conttibute to the stock of waste., The aggregate weight of material obtained in this manner forms a large percentage of the eutire weight of the crop of cocoons. When it is considered that all silk-producing countries are sources of supply, it will be seen that the bulk of fibre of this description placed at the disposal of manufacturers is very great.
Until about 1857, this waste was the most useless bye-product obtained from any of the textile industries. The world is indebted for its utilization to Samuel Cunliffe Lister, of Manningham, near Bradford, by whose mechanical genius and enterprise it was made to serve a useful purpose.
The manufacture of silk-waste differs radically from that of net or thrown silk, being much more akin to the manufacture of worsted. The different varieties of silk, such as Italian, Chinese, Japanese, and Bengal, are kept apart, owing to their varying qualities. But the waste from all may be worked together, though it is usual to separate them according to shades of colour. The
classification is generally into two shades, yellow and white ; the former is termed Italian, and the latter Chinese. Sometimes the yellow tint of the first-named sort is removed or covered by a procesa of dyeing, which imparts to it the whiteness of the latter. Should ,the material thus sophisticated he belled at a aubsequent stage, the original tint will reappear, and rnay cause defecta in the fabric into which it has to enter. It is therefore important for the manufacturer to know when it has been subjected to such treatment.
On the Continent, it is customary for spinners to work waste Bilk with the gum in it, in which state it is known as " Schappe silk." English manufacturers, however, usually prefer to clear tbe gum from it by boiling. This is the first process to which it is submitted. After boiling, the mass presents a rich lustrous appearance, but thoroughly entangled.
It is now ready for the " breaker," a. machine allied in its function and structure to the " rag devil " of the shoddy manufacture (see Woollen Manufactures), which tears, breaks, and disentangles the fibrous mass. The latter is by this means reduced to lengths from 12 in. downwards, by which it is fitted for the process of combing.
The principle of combing is aimilar to that employed in the manipulation of long wool for the production of worsted, with the modifications rendered necessary by the different nature of the material. In combing silk-waste, the material is separated into several portions, each of a different length of staple, and the combing-machine is consequently arranged to obtain this result. The first draft yields a ataple about 12 in. long, which can be apun into 100'e-140's single thread ; this is called " first drafts." The next in length ia called " second drafts," and is suitable for the production of 70's-90's. There are several successive ones, named thirds, fourths, fifths, &c., which are utilized in the production of coarser yarns. The short fibre remaining after the abstraction of the preceding lengths of ataple, and which is too short to comb, is called " ailk-noil," and is rele gated to the silk carding-machine, which differs very little from those for cotton or wool. It is subsequently treated in the same manner as those fibrea, the product being finally known as " oarded spun silk," or " short spun silk," to distinguish it from combed ailk-yarn, which is called " long-spun" or " patent silk." The perfection to which the combing process haa been carried leaves very little material available for carding purposes, and the yarn produced from the latter is disappearing ; it is going out of favour also from another cause, namely, its lack of lustre as com pared with that produced from the combing process.