FIBRE TO FABRIC /CLASS -07/SCIENCE/BEST NOTES FOR STUDY

                FIBRE TO FABRIC 

Fibres are the long, strong and flexible stud like structures that are used to make fabric.

• Natural fibres are obtained from plants and animals. 
• Cotton and jute are obtained from plants where as wool and Silk fibres are obtained from animals.
• Nylon , rayon etc are some human made automatic fibre which are made by different chemical.

ANIMAL FIBER

• Wool is obtained from fur of sheep , angoora goat,  Cashmere goat ,yak rabbit ,camel ,llama and alpaca.
• The body of this animals is covered by a thick coat of hair called fleece. 
• Silk is obtained from cocoon of silkworm.

WOOL

• Wool is  present as a thick coat of hair  on the body of wool yielding animals.
• Air  gets trapped in the spaces between the wool fibre. Since air is a bad conductor of heat ,it does not allow the body heat to escape and keeps the body warm. That is why woolen clothes are worn in winter.
• Wool has a high tensile strength and the high elasticity and it can absorb large amount of water. It is lightweight and will be easily dyed. 
• It is considerable resilient. On account of this property is the fabrics made from wool have ability to retain shape better than the fabrics made from other natural material.

Rearing and breeding of sheep

• Rearing  of ship means  to look after the Sheep, by providing them food ,shelter and healthcare.
• The person who looks after the Sheep is called the Shepherd.
• In case of animals, breeding is done to obtain animals with desired characteristics . With two individuals of desirable characteristics are selected as parents  . Then they are crossed to obtain new breed of animal having desirable characteristics of both the parents. This is called selective breeding.

Processing fibres into wool

• Once the reared  sheep have developed the thick coat of hair , it is shaved of for getting wool. Wool is obtained from sheep by a long process which involves various steps-

1. Shearing -  The process of removing hair from the body of a sheep is called shearing. Shearing does not hurt the Sheep because the uppermost layer of the Sheep is dead . Sheep are reared  in early summer so that they do not feel the heat. The hair of sheep grow again before the onset of winter and protect them from the cold weather.
2. Scouring -The process of washing the fleece of sheep to remove dust ,dirt sweat, grease ,etc is called scouring. Nowadays scouring is done by machine.
3. Sorting - The process of separating the long find quality please from the remaining inferior quality of Broken pieces is called sorting. 
4. Combing - The process of removing the birds from the fleece is called combing.
5. Dyeing - The natural fleece of sheep is black, Brown or white in colour . The fibres obtained after combining are dyed in various colour.
6. Spinning - The straightend fibres are open or twisted together to make yarn . The wool yarn is either knitted or  woven. The longer fibres are knitted into wool for sweater and the shorter fibres are woven into woolen clothes.

The quality of wool is just on the basis of thickness, length , strength and fineness of the fibre.

Silk

• Silk is a fine strong soft and Shiny fibre obtained from silkworm. It is separated from The Cucoons of silkworms and is made of a protein.
• Silk is the strongest natural fibre . Silk is an animal protein it gives a smell of burning hair when burnt.
• The rearing of silkworms for obtaining Silk is called sericulture.
• China lead the world in the Silk production . Other Silk producing countries are India and Japan.

Lifecycle of silkmoth 

1. The female Silk moth lay  the pale yellow eggs on the leaves of a tree.
2. The egg hatch in 2 weeks time to form worm like larva called Caterpillar or silkworm.
3. Now the silkworm is ready to enter the next stage of development called Pupa. Each silkworm begin spinning a cocoon by moving it head in the pattern of figure of eight . During these movements of head the silkworm secret silk in liquid form through the tiny opening in its head. Liquid Silk is coated in sericine and solidifies on contact with the air and becomes Silk fibre. The silky covering made  by the silkworm for its protection is called cucoon.
4. When the Pupa develops fully to form an adult Silk moth then the cocoons split up and a beautiful Silk moth come out.

Rearing of silkworms 

• Rearing of silkworms means to look after the silkworms by providing them proper food and shelter.
• Each female Silk moth Lays 200 to 500 eggs  at a time.
• The eggs are kept in perforated cardboard boxes on bamboo trees under hygienic and suitable temperature and humidity condition.
• The eggs are warm to a suitable temperature in an in computer for the Larvae to hatch from egg.
• A perforated sheet of paper is placed over the hatching box or tray  and chopped Mulberry leaves are spread over it.
• When the Larvae has out of the egg,  they  feed on Mulberry leaf . They eat day and night and increased enormously in size.
• After 25 to 30 days the silkworm stop eating and move to a tiny Chamber of bamboo in the tray to spin cocoons. 
• Small racks  or twigs are provided in the trays to which cucoons get attached.
• A silkworm complete its cocoon  which is about 4 CM in  about 5 days by producing about 600 to 1200 metres of thin Silk fibre.

From cocoon to silk

1. Boiling - the cocoons are  first boiled in hot water or treated in oven to kill the Larvae inside. If the larvae  are not killed and allowed to grow they will break the cucoon thereby reducing the length of silk fibre.
2. Reeling- the process of taking out thread from the cocoon is called reeling the Silk . Reeling is done in special machines which unwind the threads of fibres of silk from the cocoon.
3. Throwing - the process used to produce thrown Silk , the process is called throwing. This prevents the Silk from splitting into individual fibre .
4. Dyeing - Thrown Silk is then dyed for making colour fabric . The dyed Silk fibres are then spun into Silk thread which are woven into Silk cloth by weaver.