Wool

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Chapter: Pharmacognosy and Phytochemistry : Fibres, Sutures and Surgical Dressings

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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