These DAV Class 7 Science Notes and DAV Class 7 Science Chapter 14 Notes – Fabric from Fibre act as excellent revision resources, particularly in preparation for board exams.
Fabric from Fibre Class 7 DAV Notes
→ Wool: Wool is obtained from the body coat of some animals. These animals have fine, soft hair close to their skin. The fine and soft hair in such animals is called fleece. Sheep, goat, camel and yak are some wool giving animals.
→ Making wool from fleece: Following are the various steps in making wool from fleece:
- Shearing: The process of removal of fleece along with a very thin layer of dead skin is called shearing.
- Scouring: The fleece is washed in large tanks with the help of machines; to remove dirt and grease. This process is called scouring.
- Sorting: The process of separating hairs of different textures is called sorting.
- Dyeing: The raw fibre is dyed in different colours.
- Spinning: The raw and dyed fibres are twisted together to make yarn.
→ Silk: Silk is obtained from silkworms. Rearing of silkworms for obtaining silk is called sericulture.
→ The process of obtaining silk from silk moth has following stages:
→ Rearing of silkworms: A female silk moth lays hundreds of eggs. Eggs are stored at a suitable temperature. The eggs hatch to produce larvae which are called caterpillars. The caterpillars are kept in clean boxes where they feed on mulberry leaves. Within 20 – 30 days, the caterpillars grow significantly in size.
The caterpillar then makes a cocoon around itself. This stage is called pupa.
→ Reeling: The cocoons are collected and exposed to steam. This separates the silk fibre. Silk fibre is spun around a spindle and the process is called reeling.
→ Dyeing: Silk fibre is dyed in different colours.
→ Spinning and weaving: Silk fibres are spun into threads. Threads are then woven into cloth.
→ Fibre: A thin continuous strand of a matter is called fibre.
→ Yarn: Fibres are twisted together to make yarns.
→ Cloth: Yarn is woven to make cloth.
→ Knitting: In this method of making cloth, a single yarn is used.
→ Weaving: In this method of making cloth, more than one yarn is used.
→ Sericulture: Rearing of silkworm for obtaining silk is called sericulture.