Wool is the fibre derived from...
Wool is the fibre derived from the hair of animals of the Caprinae family, principally
sheep and goats, but the hair of other mammals such as alpacas may also be called wool.
This article deals with the wool produced from domestic sheep.
Wool is the fibre produced as the outer coat of sheep. Most of the fibre from domestic
sheep 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.
Both the scaling and the crimp make it possible 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 fineness 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.
Wool straight off a sheep contains a high level of grease (thus "greasy wool") which
contains valuable lanolin. In this state it can be worked into yarn or knitted into
water-resistant mittens, such as those of the Aran Island fishermen. The grease is
generally removed for processing by scouring with detergent and alkali.
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.
The fibre diameter of wool varies from 15 micrometres (superfine merino) to 30 or more
micrometres for the coarser wools. The finer diameters are generally more valuable.
Global wool production is approximately 1.3 million tonnes per annum of which 60% goes
into apparel. Australia, China and New Zealand are leading commercial producers of wool.
Most Australian wool comes from the merino breed. Breeds such as Lincoln and Romney
produce coarser fibres and wool of these sheep is usually used for making carpets.
In the United States, Texas, New Mexico and Colorado also have large commercial sheep
flocks and their mainstay is the Rambouillet (or French Merino). There is also a thriving
'home flock' contingent of small scale farmers who raise small hobby flocks of specialty
sheep for the handspinning market. These small scale farmers may raise any type of sheep
they wish, so the selection of fleeces is quite wide.
Sheep have been a friend to people for over 10,000 years, providng both meat and
clothing. There are many different breeds of sheep. Some are raised mainly for meat,
and others primarily for their wool. Sheep are valuable because they often graze land
that other livestock cannot. Sheep eat grass and hay.
Sheep usually give birth once a year and have 1-3 lambs. They normally live to be
about 8 years old. One year's growth of fleece is about 8 pounds of wool. Sheep are
usually shorn once a year. The sheep shearer uses a machine that is like the clippers
used to trim a dog's fur. Wool straight from the sheep is called raw wool. Raw wool
may go through more than 70 processing steps to assure that fabrics made from the wool
are of the highest quality. One of the best things about wool fabrics is that they are
flame resistant, so they are safer to wear. Wool also provides excellent protection
from cold and wet weather. Even if your wool sweater gets wet from snow or rain, it
will still keep you warm. Wool also wears well and lasts for a long time.