Fibre to fabric class 7 NCERT

Subject: Fibre to fabric class 7 NCERT Notes

Fibres:- Thread/filament which forms constituent of various composite material.

Types of fibres:- two types

1. Natural fibres

2. Artificial fibres

Natural fibres obtained from plants and animals.

 Example:- Jute, Flax, Cotton, Hemp, Coir, tree wool, wool, silk etc.

Man-made fibres are called artificial fibres. 

Example:- Nylon, Rayon(Artificial silk), Polyester etc 

In this chapter we will learn about Animal fibres:- wool and silk

Fleece:- hair of sheep or yak from which wool obtained.

Animal fibre:-Fibres obtained from animals e.g. Wool and Silk

WOOL:- 

• Obtained from skin hair of fat animals.
• Wool comes from sheep, goat, yak and some other animals.

Why animals have such fur?

• Because hair trap a lot of air.
• Air is a bad conductor of heat 
• So hair keeps these animals warm.
• Wool is derived from these hairy fibres.

Types of fibres that obtained from sheep fleece:-

1. The coarse beard hair

2. The fine soft under- hair close to skin.

Fine hair provide the fibres for making wool.

Selective breeding:-

•  The process of selecting parents for obtaining special characters in their offspring, such as soft under hair in sheep, us terms 'selective breeding'.

Animals that yield wool:- 

• Commonly available wool in market is sheep wool.
• Yak wool is common in Tibet and Ladakh.
• Mohair is obtained from angora goats found in hilly region such as Jammu and Kashmir.
• Also obtained from goat hair.
• Under fur of Kashmir goat is soft and is used to woven into fine shawls called Pashmina shawls.
• Camel fur, Llama and Alpaca found in South America also yield wool.

FROM FIBRES TO WOOL:- 

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

Rearing and breeding of sheep:-

• Feeding sheep properly by providing them grass mixed with pulses, corn, Jowar, oil cakes and minerals.
• In winter, sheep are kept indoors and fed on leaves, grain and dry fodder.
• Certain breeds of sheep have thick coat of hair on their body which yields good quality wood in large quantities. 
• Once the reared sheep have developed a thick growth of hair, hair is shaved off for getting wool.

Sheep are reared in many parts of our country for wool. Some Indian breeds of sheep are listed below:-

PROCESSING FIBRES INTO WOOL:-

• The wool which is used for knitting sweaters or for wearing shawls is the finished product of a long process, which involves the following steps:-

STEP 1:- SHEARING:- 

• The fleece of sheep along with a thin layer of skin is removed from its body. This process is called shearing.
• The uppermost layer of skin of sheep is dead so it does not hurt the sheep.
• Hair removed during summer so that they enable to survive without protective coat of hair.

STEP 2:- SCOURING:- 

• Sheared skin is washed in tanks to remove grease, dust and dirt. This is called scouring.

STEP 3:- SORTING:-

• In factory , different textures of hairy skin are seperated .

STEP 4:- BURR PICKING:-

• Burr are small fluffy fibres 
• They are picked out from the hair.
• The fibres are scoured again and dried.
•  This is the wool ready to be drawn into fibres.

STEP 5:- DYEING:- 

• The fibres can be dyed in various colours the natural fleece of sheep and goats is black, brown and white.

STEP 6:- ROLLING INTO YARN:-

• The fibres are straightened, combed and rolled into yarn. 
• The longer fibres are made into wool for sweaters and shorter fibres are spun and woven into woollen cloth.

The process of fibres into wool can be represented as follows:-

Shearing ---> Scouring ---> Sorting ---> Cleaning of burrs ---> Dyeing ---> Rolling.

SILK:- 

• Animal fibres
• Silkworms spin the silk fibres.
• Rearing of silkworms for obtaining silk is called sericulture.

LIFE HISTORY OF SILK MOTH:-

• 1. Female silk moth lays eggs from which larva hatch .
• It's larva is called silkworms or caterpillars.
• 2. They grow in size, weave a net to hold itself .
•  It then swings its head from side to side 
• During movements of head the caterpillar secretes fibre made of a protein.
• This protein hardens on explosive to air and becomes silk fibre.
• 3. Soon the caterpillar completely covers itself by silk fibres and turn into pupa.
• This covering is known as cocoon.
• 4. Further development of pupa into moth continues inside the cocoon.

NOTE:- Soft silk yarn is as strong as a comparable thread of steel.

• The silk yarn (thread)  is obtained from the cocoon of silk moth.
• There is a variety of silk moth and so different types of silk is available to us such as tassar silk, mooga silk, kosa silk, eri silk etc 
• The most common silk moth is the mulberry silk moth.
• This silk is soft, lustrous and elastic and can be dyed in beautiful colours.

FROM COCOON TO SILK:-

• For obtaining silk, moth are reared and their cocoons are collected to get silk threads.

REARING SILKWORM:- 

• 1. Female silk moth lays hundreds of eggs at a time .
• 2. Farmers keep eggs under hygienic conditions and under suitable conditions of temperature and humidity.
• 3.Eggs are warned to a suitable temperature for the larvae to hatch from eggs.
• This is done when mulberry trees bear a fresh crop of leaves.
• 4. The larvae eat day and night and increased in size.
• After 20-30 days the caterpillars stop eating and move to a tiny chamber of bamboo in the tray to spin cocoons.
• The caterpillar or silkworm spins the cocoon inside which develops the silk moth.

PROCESSING SILK:- 

• A pile of cocoons is used for obtaining silk fibres.
• The cocoons are kept under the sun or boiled or exposed to steam.
• The silk fibres separate out.
• The process of taking out threads from the cocoon fro use as silk is called reeling of silk.
• Reeling is done by machine.
• Silk fibres are then spun into silk threads, which are woven into silk cloth by weavers.

KEYWORDS:-

1.COCOON:-The caterpillar completely covers itself by silk fibres and turn into pupa.

This covering is known as cocoon

2.FLEECE:-Hair of sheep or yak from which wool obtained.

3.REELING:-The process of taking out threads from the cocoon fro use as silk is called reeling of silk.

4.SCOURING:-Sheared skin is washed in tanks to remove grease, dust and dirt. This is called scouring

5.SERICULTURE:-Rearing of silkworms for obtaining silk is called sericulture.

6.SHEARING:-The fleece of sheep along with a thin layer of skin is removed from its body. This process is called shearing.

7.SILK MOTH:-A large moth with a caterpillar that spins a protective silken cocoon.

8.SILKWORM:-Worm whose caterpillar make silk fibre.

9.SORTING:-In factory , different textures of hairy skin are seperated .

Thankyou ....