Characteristics

The amount of crimp corresponds to the thickness of the wool fibers. A fine wool like Merino may have up to a hundred crimps per inch, while the coarser wools like karakul may have as few as one to two crimps per inch. Hair, by contrast, has little if any scale and no crimp, and little ability to bind into yarn. On sheep, the hair part of the fleece is called kemp. The relative amounts of kemp to wool vary from breed to breed, and make some fleeces more desirable for spinning, felting, or carding into batts for quilts or other insulating products.

Wool possesses much greater ability to return to its natural length after being stretched than any artificial fiber. In water or steam, wool can stretch to about twice its length without breaking. Because of elasticity, woollen garments may be stretched or crushed without losing their shape. Also, this fiber felts readily, by heat, moisture, and pressure being applied during the manufacturing processes.

Wool fibers are hygroscopic. This means wool has the power to readily absorb and give off moisture. It can absorb moisture up to one-third of its own weight. Synthetic fibers can only absorb 2-3 percent of moisture before they begin to feel wet. Additionally, wool absorbs sound and reduces noise level considerably like many other fabrics. Wool is generally a creamy white color, although some breeds of sheep produce natural colors such as black, brown, silver, and random mixes.

Wool is harder to ignite than most synthetic and cotton fibers used in equivalent products (higher ignition temperature); it has lower rate of flame spread, low heat release, and low heat of combustion; doesn't melt or drip; forms a char which is insulating and self-extinguishes; and contributes less to toxic gases and smoke than other flooring products when used in carpets. Wool carpets are specified for high safety environments such as trains and aircraft. Wool is usually specified for garments for fire-fighters, soldiers, and others in occupations where they are exposed to the likelihood of fire.

Wool is static resistant as the retention of moisture within the fabric prevents a build up of static electricity. Woollen garments are much less likely to spark or cling to the body. The use of woollen car seat covers or carpets reduces the risk of a shock when a person touches a grounded object.

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