Wool consist of hairs from the fleece of sheep Ovis aries Linn., belonging to family Bovidae.
WOOL
Biological Source
Wool consist of hairs from the fleece of sheep Ovis aries Linn., belonging to family
Bovidae.
Geographical Source
The worlds leading producers of wool are Australia (25%),
China, and New Zealand (11%), while Turkey, Iran, India, and the United States
(Texas, New Mexico) contribute to 2%.
History
The use of wool for clothing and other fabrics dates back to
earliest civilizations. The wool trade was a serious business during medieval
times and English wool export had contributed significantly as a source of
income to the crown. Smuggling of wool was considered a serious offence and was
punished with cutting off the hand. Wool trade had also helped Medicis of
Florence in Renaissance in building up their wealth and banking. Spain with
royal permission exported Merino lambs. By the end of 19th century German wool
(from sheep of Spanish origin) overtook British wool but later by 1845 the
Australian wool trade eventually overtook the German wool.
Preparation
Wool is the fibre derived from the hair of animals of the
Caprinae family, mainly sheep and goats. It is produced as the outer coat of
sheep. The fibre obtained from domestic sheep has two qualities which
differentiate it from hair or fur. The fibres have scales which overlap like
shingles on a roof and it is crimped. The amount of crimp is directly
proportional with the fineness of the wool fibres and the fine wool (like
merino) have up to a 100 crimps per inch, whereas coarser wools (like karakul)
have one or two crimps per inch.
The hairs from sheep are removed during the shearing time.
After shearing, the wool is separated into five main categories: namely fleece,
pieces, bellies, crutchings, and locks. It is then cleaned from dirt and high
level of grease (thus ‘greasy wool’) which contains valuable lanolin is present
on the hair. The grease is generally removed for processing by scouring with
detergent and alkali. The wool is then treated with hydrogen peroxide for
bleaching, it is then washed properly and spreaded on wire nettings and dried
under hot air.
Description
Wool is generally a creamy white colour but some of the
breeds of sheep naturally produce black, brown (also called moorit) and grey
coloured wool. The wool is smooth, elastic, slippery to touch and slightly
curly. Diameter of wool varies from 15 μm (superfine merino) to 30 or 40 μm. The finer the diameters the greater its value is. Wool is soluble in warm alkaline solutions, but not in dilute or
strong acids.
Chemical Constituents
Wool mainly consists of a sulphur containing protein called
keratin. Keratin is composed of amino acid like cystine.
Chemical Tests
1. Solubility test: It is easily
soluble in warm alkali.
2. Wool when treated with Con.
Hydrochloric acid, it does not produce any effect but dissolves silk.
3. When treated with cuoxam solution,
it does not dissolve but swells the wool and produces blue colour.
4. Solution of wool treated with lead
acetate produces black precipitate due to high sulphur content.
Uses
It is used as a filtering aid and straining medium and in
the manufacture of clothing, carpeting, felt and it is also used to absorb
odours and noise in heavy machinery and stereo speakers.
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