=Silk Cotton.= On account of the high price of silk various attempts
have been made to find satisfactory substitutes for it. There are
certain seed coverings of plants that contain very fine hair-like
fibers with a luster almost equal to silk, but the staples are short,
and the texture weak. The Kapok plant furnishes most of the commercial
silk cotton on the market. The fibers of Kapok are thin and
transparent. They ar
extremely light, and the length is less than
half an inch. Silk cotton has a smooth surface and therefore cannot be
spun like true cotton which has corded edges.
=Artificial Silk.= Since seed hairs are composed, like all vegetable
fibers, of cellulose, attempts have been made to prepare an artificial
silk product from waste paper--that is, by treating waste paper or
wood or cotton fibers with various chemicals in order to obtain pure
cellulose. This artificial silk is perhaps the most interesting of
artificial fibers, but its manufacture is dangerous, owing to the ease
with which it catches fire and explodes. Cellulose, chemically
treated, can be transformed into a fluid solution known as collodion.
The collodion is placed in steel cylinders and expelled by pressure
through capillary tubes. After drying, denitration, and washing, it
may be spun and dyed like natural silk. Colored threads may be
produced by the addition of certain dyes.
Artificial silk bears a deceptive resemblance to the natural article,
and has nearly the same luster. It lacks the tensile strength and
elasticity, and is of higher specific gravity than true silk.
=Tests.= A simple way of recognizing artificial silk is by testing the
threads under moisture, as follows: First, unravel a few threads of
the suspected fabric, place them in the mouth and masticate them
vigorously. Artificial silk readily softens under this operation and
breaks up into minute particles, and when pulled between the fingers
shows no thread, but merely a mass of cellulose or pulp. Natural silk,
no matter how thoroughly masticated, will retain its fibrous strength.
The artificial silk offers no resistance to the teeth, which readily
go through it; whereas natural silk resists the action of the teeth.