Fibre to Fabric - Revision Notes

 CBSE Class 7 Science

Revision Notes 
Chapter – 3
Fibre to Fabric

  • Fibres: Long, fine, continuous threads or filaments are obtained from plants and animals.
    Two types of fibres:
    (i) Animal fibres
    (ii) Plant fibres
  • Silk and Wool are common animal fibres
  • Silk comes from silkworms and wool is obtained from sheep, goat and yak. Hence silk and wool are animal fibres.
  • The hairs of camel, llama and alpaca are also processed to yield wool.
  • In India, mostly sheep are reared for getting wool.
  • Sheep hair is sheared off from the body, scoured, sorted, dried, dyed, spun and woven to yield wool.
  • Wool: Sources of Wool: Wool is obtained from sheep, yak (Tibet and Ladakh), Angora goat, goat, camels, llama and Alpaca (South America)
  • Obtaining wool fibre: Shearing: Fleece of the sheep along with a thin layer of skin is removed from its body.
  • Processing of Wool Fibre:
    (i) Scouring: Sheared hair is cleaned and washed in tanks to remove grease, dust and dirt.
    (ii) Sorting: Cleaned hair is sent to a factory where hair of different textures are separated.
    (iii) Hair is sent into a ‘Carding’ machine where the loose wool fibres are combed into a sheet and then twisted into a rope or silver.
    (iv) This silver is twisted and stretched into a yarn.
    (v) The yarn is wound to form balls of wool.
  • Silk
  • Silkworms are caterpillars of silk moth.
  • During their life cycle, the worms spin cocoons of silk fibres.
  • Silk fibres are made of a protein.
  • Silk fibres from cocoons are separated out and reeled into silk threads.
  • Weavers weave silk threads into silk cloth.