Wool

Wool is the fibre derived from the fur of animals of the Caprinae family, principally sheep, but the hair of certain species of other mammals such as goats, alpacas and rabbits may also be called wool. This article deals explicitly with the wool produced from domestic sheep. more...

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Wool

Wool has two qualities that distinguish it from hair or fur: it has scales which overlap like shingles on a roof and it is crimped; in some fleeces the wool fibres have more than 20 bends per inch.

Characteristics

Wool's scaling and crimp make it easier to spin and felt the fleece. They help the individual fibres attach to each other so that they stay together. Because of the crimp, wool fabrics have a greater bulk than other textiles and retain air, which causes the product to retain heat. Insulation also works both ways; bedouins and tuaregs use wool clothes to keep the heat out.

The amount of crimp corresponds to the thickness of the wool fibres. 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 is generally a creamy white colour, although some breeds of sheep produce natural colors such as black, brown (also called moorit) and grey.

Processing

Wool straight off a sheep contains a high level of grease which contains valuable lanolin, as well as dirt, dead skin, sweat residue, and vegetable matter. This state is known as "grease wool" or "wool in the grease". Before the wool can be used for commercial purposes it must be scoured, or cleaned. Scouring may be as simple as a bath in warm water, or a complicated industrial process using detergent and alkali. In commercial wool, vegetable matter is often removed by the chemical process of chemical carbonization. In less processed wools, vegetable matter may be removed by hand, and some of the lanolin left intact through use of gentler detergents. This semi-grease wool can be worked into yarn and knitted into particularly water-resistant mittens or sweaters, such as those of the Aran Island fishermen. Lanolin removed from wool is widely used in the cosmetics industry.

After shearing, the wool is separated into five main categories: fleece (which makes up the vast bulk), pieces, bellies, crutchings and locks. The latter four are packaged and sold separately. The quality of fleece is determined by a technique known as wool classing, whereby a qualified woolclasser tries to group wools of similar gradings together to maximise the return for the farmer or sheep owner.

Read more at Wikipedia.org