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.