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 are 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.