- Books Name
- CBSE Class 7 Science Book
- Param Publication
- CBSE Class 7
(i) Wool :
We wear sweaters in winter to protect ourselves from the cold. Wool is a fibre obtained from animal such as sheep, goat, yak and lamb. Animals from which we get wool bear a thick coat of hair on their bodies.
Wool fibres keep us warm the thick coat of hair traps a lot of air, thereby creating an insulating barrier.
Wool is a fibre obtained from the fleece (hairy growth) of these animals. Wool fibre is made up of protein. It is usually white in colour, although, it can also be brown or grey. Wool is mainly derived from sheep.
Wool comes from sheep, llama, alpaca, guanaco and vicuna.
• Difference between fleece and hair
Fleece : Thick covering of wool on a sheep, used to make a piece of clothing Hair : The mass of thin thread like structure that grows out of the skin
(a) Wool from Sheep
A sheep’s hairy coat has two types of fibres :
(i) the coarse beard hair and (ii) the soft under-hair, found close to the skin. It is the soft under-hair that is used to make wool. Scientists have developed certain breeds of sheep that only have the soft under-hair.
The wool from different varieties of sheep differes in fineness, shine, length, and strength. The finest wool is obtained from the Merino, a breed of sheep originally from Spain. Their wool is very soft and light, and is therefore used in making the finest woollen clothes.
(b) Rearing of Sheep
In India, sheep are reared in the hilly regions of Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Arunachal Pradesh, Sikkim, Punjab, Haryana, Rajasthan, and Gujarat.
• Breed : A particular type of animal developed for certain desirable characteristics
• Rearing : Keeping animals and caring for them to obtain useful products
(c) Wool Production
Sheep hair is sheared off from the body, scoured, graded or sorted, dried, dyed, spun and woven to yield wool.
• Shearing : The fleece of the sheep along with a thin layer of skin is removed from its body. This is called shearing.
Sheep are usually shorn annually in the spring/summer months.
Just as a haircut does not hurt us, shearing does not hurt the sheep, it actually helps them by removing the heavy woollen coat that they do not require in summer.
• Scouring :The sheared skin with hair is thoroughly washed in tanks to remove grease, dust and dirt. This is called scouring.
It is done with the help of machines.
• Grading or Sorting : In this process, the wool is sorted on the basis of length, colour, texture, and the ease with which it can be dyed (coloured).
• Dyeing : As the natural colour of fleece is white,brown or black, the sheared wool is dyed in different colours.
• Drying : In this process, containers of wool are put through rollers to squeeze out as much water as possible. Then the wool is weighed and packed into bales. The bales are transported to the mills where they are processed further.
• Making of Yarn :
Figure explains how the fleece is woven into yarn.
(d) Health Hazards in the wool industry :
• While sorting wool, workers (sorters) get infected by bacteria, anthrax, which causes fatal blood disease called sorter’s disease. Such risks faced by workers in any industry are called occupational hazards.
Nowadays, this disease occurs rarely because of the use of vaccines for prevention.
(e) Wool from other Animals
• Angora wools is obtained from angora goats, which are found in hilly areas like Jammu and Kashmir.
• Yak wool is commonly found in areas like Laddakh and Tibet.
• Wool obtained from Kashmir goat is soft and is used to weave fine quality shawls called Pashmina shawls.
• Wool is also obtained from fur (hair) on the body of camels. It is used in making carpets etc.
• Llama and Alpaca, found in South America, also yield wool.
• Wool is used for making coats, suits, shawls, scarves, gloves and carpets. It traps air and so it has insulating properties.