Wool is produced by the hair follicles of small cells in the skin. These hair follicles are located on the upper layer of the skin, known as the epidermis, as the wool fibers grow, pushing down into the second layer of skin called dermis. Follicle can be divided into primary follicle and secondary follicle. The primary follicle produces three types of fibers: cotton balls, medullary fibers and real hair fibers. Secondary follicles can only produce real wool fibers. The medullary fibers have almost the same characteristics as hair and are long, but not curled and elastic. Kemp fibers are very rough and fall off.
New Zealand merino wool and carded wool on the wool table
The scaling and crimping of the wool make it easier to spin wool by helping each fiber attach to each other, so they stay together. Because of the curl, wool fabric has a larger volume than other textiles, and they keep the air, which keeps the fabric warm. Wool has a high specific heat coefficient, which impedes heat transfer. The bedouin are insulated from the use of woollen clothing by the tuareg, which has benefited the desert people.
When a tiny barb on the surface of a wool fiber is hooked together, the wool felt under hammer or other mechanical agitation.
Wool has several properties that differ from hair or fur: it is crimp and elastic.
The curl corresponds to the fineness of wool fibers. Fine wool like merino may have as many as 100 curls per inch, while a coarse wool like karakul might have only one or two. By contrast, hair has almost no scales, no curls, and the ability to combine yarns is small. In sheep, the hair part of the wool is called keng. Relative number of wool and wool from variety to variety, and make some more suitable for wool textile, matted or combing quilt or other insulating felt, including the famous Scottish tweed fabric.
Wool fibers absorb water easily, but not hollow. Wool can absorb almost a third of its weight. Wool absorbs sounds like many other fabrics. It is usually milky white, although some varieties of sheep produce natural colors such as black, brown, silver and haphazardly mixed.
Wool is ignited at a higher temperature than cotton and some synthetic fibers. It has a lower flame spread rate, lower heat release rate, lower combustion heat, not melting or dropping; it forms a kind of insulating and self-extinguishing charcoal, contributing less gas and smog to toxic substances than other flooring products. Wool carpets are designated for highly secure environments such as trains and aircraft. Wool is usually designated for fire fighters, soldiers and other occupations that may have a fire hazard.
Wool is thought to be allergic by the medical community.