Class 7 | Science | Chapter-3 | Fibre to Fabric Notes | By Dharmender

Class 7           Science

Chapter-3

Fibre to Fabric Notes

Fleece- The hair of sheep and yak.

Fibres- Fibres are long, Fine, Continuous thread or filament are obtained from plants and animals.

Fibres are divided into two categories-

(i)  Animal Fibres

(ii) Plant Fibres

Animal Fibres are silk and wool

Wool is obtained from sheep, goat, camel, etc.

Silk is obtained from silkworm.

Wool- Wool comes from sheep, goat, yak and some other animals. These wool yielding animals bear hair on the body and thick coat of hair.Hair trap a lot of air. Air is poor conductor of heat. So hair keeps these warm. Wool is derived from these hairy fibres.

The sheep has two types of fibres that from its fleece-

(i)   The coarse beard hair

(ii)  The fine soft under hair close to the skin

The process of selecting parents for obtaining special characters in their offspring, such as soft under hair in sheep, is termed 'selective breading'.

Animals that yield wool-

Yak- Yak wool is common in Tibet and Ladakh.

Angora Goat- Angora wool is obtained from angora goats. These found in hilly region(j&k).

The under fur of Kashmiri goat is soft. It is woven into fine shawls called Pashmina shawls.

The fur on the body of camel is also used as wool.

Llama and Alpaca are found south America, also yield wool.

From fibres to wool-

For obtaining wool, sheep are reared. Their hair is cut and processed into wool.

Processing fibres into wool-

Step I- The fleece of the sheep along with a thin layer of skin is removed from its body. This process is called shearing.

Step II- The sheared skin with hair is thoroughly washed in tanks to remove grease, dust and dirt. This is called scouring.

Step III- After scouring, shorting is done, the hairy skin is sent to a factory where hair of different textures are separated or sorted.

Step IV- The small fluffy fibres, called burrs, are picked out from the hair. These are the same burrs which somtimes appears on your sweaters. The fibres are scoured again and dried. This is the wool ready to drawn into fibres.

Step V- The Fibres can be dyed in various colours, as the natural fleece of sheep and goats is black, brown or white.

Step VI- The fibres are straightened combed and rolled into yarn.

Silk- 

Silk is made when silkworm spin the silk fibres.

Sericulture- The rearing of silkworms for obtaining silk is called Sericulture.

Life history of silk moth-

The female silk moth lays egg on mulberry leave and they made silkworm and then they form developing moth and cocoon.

Rearing silkworms- A female silk moth lays hundreds of eggs at a time. The eggs are stored carefully on strips of cloth or paper and sold to silkworm farmers. The farmers keep eggs under hygienic conditions, the eggs are warmed to a suitable temperature fir the larvae to hatch from eggs. This is done when mulberry trees bear a fresh crop of leaves. The larvae called caterpillars or silkworm, eat day and night and increase enormously in size. The larvae are kept in clean bamboo trays along with freshly chopped mulberry leaves. After 25 to 30 days, the caterpillars stop eating and move to a tiny chamber of bamboo in small racks or twigs may be provided in the trays to cocoon get attached. The caterpillar or silkworm spin the cocoon inside which develops the silk moth