HOW SPUN SILK IS MADE

Every manufacturer saves everything he can, and even the waste silk which cannot be wound on reels is turned into a salable product]

The moth whose coc.o.o.n provides most of our silk is called the "bombyx mori." There are others, however, and from some of these tussah silk, Yamamai, and Shantung pongee are woven. These wild moths produce a stronger thread, but it is much less smooth than that of the bombyx.

There is also a great amount of "wood silk," or artificial silk, on the market. To make this, wood pulp is dissolved in ether and squirted through fine jets into water. It is soon hard enough to be twisted into threads and woven. It makes an imitation of silk, bright and l.u.s.trous, but not wearing so well as the silk of the silkworm.

Nevertheless, for many purposes it is used as a subst.i.tute for silk, and many braids and pa.s.s.e.m.e.nteries are made of it. Then, too, there are the "mercerized" goods, which often closely resemble real silk, although there is not a thread of silk in them. It was discovered many years ago that if a piece of cotton cloth was boiled in caustic soda, it would become soft and thick and better able to receive delicate dyes. Unfortunately, it also shrank badly. At length it occurred to some one that the cloth might be kept from shrinking by being stretched out during the boiling in soda. He was delighted to find that this process made it more brilliant than many silks.

The threads that fasten the coc.o.o.n to the bush and those in the heart of the coc.o.o.n are often used, together with the fiber from any coc.o.o.ns through which the worms have made their way out. This is real silk, of course, but it is made of short fibers which cannot be wound. It is carded and spun and made into fabric called "spun silk," which is used extensively for the heavier cla.s.ses of goods. Then, too, silks are often "weighted"; that is, just before they are dyed, salts of iron or tin are added. One pound of silk will absorb two or three pounds of these chemicals, and will apparently be a heavy silk, while it is really thin and poor. Moreover, this metallic weighting rubs against the silk fiber and mysterious holes soon begin to appear. A wise "dry cleaner" will have nothing to do with such silks, lest he should be held responsible for these holes. It is this weighting which produces the peculiar rustle of taffeta; and if women would be satisfied with a taffeta that was soft and thin, the manufacturers would gladly leave out the salts of iron, and the silks would wear much better. Cotton is seldom mixed with the silk warp thread; but it is used as "filling"

in a large cla.s.s of goods with silk warp. The custom has arisen of advertising such goods as "silk," which of course is not a fair description of them. Advertis.e.m.e.nts sometimes give notice of amazing sales of "Shantung pongee," which has been made in American looms and is a very different article from the imported "wild silk" pongee.

With so many shams in the market, how is a woman to know what she is buying and whether it will wear? There are a few simple tests that are helpful. Ravel a piece of silk and examine the warp and woof. If they are of nearly the same size, the silk is not so likely to split. See how strong the thread is. Burn a thread. If it burns with a little flame, it is cotton. If it curls up and smells like burning wool, it is probably silk. Another test by fire is to burn a piece of the goods. If it is silk, it will curl up; if it is heavily weighted, it will keep its shape. If you boil a sample in caustic potash, all the silk in it will dissolve, but the cotton will remain. If the whole sample disappears, you may be sure that it was all silk. Soft, finely woven silks are safest because they will not hold so much weighting.

Crepe de chine is made of a hard twisted thread and therefore wears well. Taffeta can carry a large amount of weighting, and is always doubtful; it may wear well, and it may not. There is always a reason for a bargain sale of silks. The store may wish to clear out a collection of remnants or to get rid of a line of goods which are no longer to be carried; but aside from this, there is usually some defect in the goods themselves or else they have failed to please the fashionable whim of the moment. Silk is always silk, and if you want it, you must pay for it.