MATERIALS AND HOW TO TEST THEM
like the shingles of a roof. Because of its kinkiness, scales, and elasticity it can be spun into very fine yarn. Wool fibers may be from one to eight inches long. When wet wool becomes soft and plastic and if pressed, the fiber scales become entangled causing the wool to felt. This is the reason wool requires careful laundering. Since it is a poor conductor of heat, it is suitable for winter fabrics.
Silk is a solid rod-like filament secreted by the silk worm, a kind of caterpillar. This fiber the worm spins about itself, forming an envelope or cocoon. The long strong even filaments are many yards tn length and, when reeled from the cocoons, make the better grades of silk. The short waste ends, when spun into so-called “spun silk” yarn, make the poorer grades.
Cotton is a flat twisted tubelike vegetable fiber, varying from a little less than one inch to two inches in length. It is not as strong as silk or linen but is stronger than wool. It is less elastic than silk or wool but more so than linen. Being a good conductor of heat it Is chosen for our warm weather garments. The spinning qualities of cotton depend upon the length, twist, and fineness of the fiber.
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