NCERT Class 7 Science Chapter 3: Fibre to Fabric YouTube Lecture Handouts

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Silk & Wool

Wool

Obtained form:

  • Sheep

  • Goat – Mohair (Angora goat) in J&K & Pashmina from Kashmiri goats

  • Yak – Tibet, Ladakh

  • Alpaca & Llama in South America

  • Camel

  • Chiru (Tibetan Antelope) – Shahtoosh

  • Rabbit – Angora wool

Sheep fleece - coarse beard hair & fine soft under-hair close to the skin (fine one used for wool)

Fibre to Wool

Rearing and Breeding - Jammu & Kashmir, Himachal Pradesh, Uttaranchal, Arunachal Pradesh and Sikkim, or the plains of Haryana, Punjab, Rajasthan and Gujarat

Sheep varieties

  • Lohi: Good quality wool - Rajasthan, Punjab

  • Rampur bushair: Brown fleece - UP, Himachal Pradesh

  • Nali: Carpet wool - Rajasthan, Haryana, Punjab

  • Bakharwal: For woollen shawls - Jammu and Kashmir

  • Marwari: Coarse wool – Gujarat

  • Patanwadi: For hosiery – Gujarat

Selective breeding is done

Image of Processing Fibre to Wool

Image of Processing Fibre to Wool

Image of Processing Fibre to Wool

Processing Fibre to Wool

  • Shearing: fleece with thin layer is removed in summers (similar to shave)

  • Scouring: Sheared skin with hair is thoroughly washed in tanks to remove grease, dust and dirt

  • Sorting: Texture is separated

  • Picking: Burrs (small fluffy fibres) are picked out from hair

  • Dyeing: Natural color is black, brown and white

  • Rolling: Longer fiber are made into wool for sweaters; short fibre are spun into cloth while long are made into wool

Occupational Hazard – Anthrax (by bacteria) – fatal blood disease called sorter’s disease

Silk

  • Sericulture – rearing silkworms for obtaining silk

  • Female lay egg from, which larva is hatched and called as caterpillar.

  • The eggs are stored carefully on strips of cloth or paper and sold to silkworm farmers.

  • The larvae are kept in clean bamboo trays along with freshly chopped mulberry leaves. After 25 to 30 days, the caterpillars stop eating.

Image of Rearing Silkworms

Image of Rearing Silkworms

Image of Rearing Silkworms

  • They grow into pupa (weaves a net to hold itself) - it swings its head from side to side in the form of the figure of eight (8).

  • Caterpillar secretes protein that hardens on exposure to air and becomes silk fibre – covering is known as cocoon

  • Cocoons are kept under the sun or boiled or exposed to steam – take out thread from cocoon and called as reeling of silk

  • Most common silk moth is mulberry silk moth

  • Others – kossa, mooga, kosa, eri

  • Silk – soft, elastic and lustrous

  • It can be artificial and natural (burning test)

  • Silk from China: Si-Lung-Chi was asked by Huang-Ti to find cause of damaged leaves of mulberry leaves. It was guarded but later spread by silk route.