Animal Fibers

There are several animal fibers, each obtained from a different source, but only two are recognized as major textile fibers. They are wool and silk. (Minor hair fibers – camel, llama, alpaca, mohair, cashmere, vicuna, guanaco, rabbit, and qiviut.

WOOL

Wool fiber grows from the skin of sheep. It is composed of a protein known as keratin. Wool is a relatively coarse fiber. It is crimpy (wavy) and has scales on it surface. Depending upon the breed of sheep, the appearance of the wool varies with some having a great deal of crimp and smaller, finer scales to those having little crimp and coarser scales. The finer, softer, warmer fibers have more numerous and smoother scales. The thicker, coarser, less-warm fibers have fewer and rougher scales. The better fibers with more crimp and finer scales are duller in appearance than the poorer quality wool fibers with fewer scales. Underneath the scales is the main fiber body consisting of intermediate cells that hold the color pigment. These cells provide the fiber’s strength and elasticity. In the center of the fiber is the medulla, which consists of spiral-shaped, air-filled cells. Some wool fibers that have no cortical (outer) layer are compensated with a larger proportion of modularly cells. This fact lessens the affinity for dyes, because the medulla has more fat than has the rest of the fiber. The finer wools, having no medulla, absorb dyes more readily. Two striking characteristics of wool fiber are its susceptibility to heat and its felting property, which is caused by the scales on the surface. Because of this only pressure, heat, and moisture are required to make wool fibers into the type of fabric called felt.

SILK.

It is a fine continuous strand unwound from the cocoon of a moth caterpillar known as the silkworm. While silkworms are generally cultivated, another type, wild (or tussah) silk, is obtained from uncultivated silkworm cocoons. The later produces a coarser fiber. Silk is essentially composed of protein. Silk fiber is relatively lustrous, smooth, lightweight, strong, and elastic. Historically, it has always been a highly desired fiber which has been used for apparel, home furnishings, and upholstery. Its desirability is one of the factors that prompted the production of manmade fibers to simulate silk.