SCIENCE FIBRE TO FABRIC
How Silk is Obtained Silk
Silk is obtained from silkworms. Hence, it is also a type of animal fibre. The rearing of silkworms for obtaining silk is called sericulture.
Silkworm
Life history of silk moth
The female silk moth lays eggs from where larvae emerge; they are called caterpillars or silkworms. Before entering its next stage called pupa, a silkworm weaves a net to hold itself. The movements of the head of the silkworm secrete fibre made of protein which hardens on exposure to air and becomes silk fibre. Soon, the caterpillar spins a covering called cocoon from silk fibres which protects the pupa. The further development of pupa into moth continues inside the cocoon. An adult silk moth emerges from the cocoon.
Life History of Silkworm
www.topperlearning.com 2
SCIENCE FIBRE TO FABRIC
Types of silk
Silk fibres are used for weaving silk cloth. Silk thread is obtained from the cocoon of the silk moth. Silk obtained from different varieties of silk moth vary in texture. They may be coarse, silky, shiny etc. The different varieties of silk are tassar silk, mooga silk, kosa silk etc. The most common silk moth is the mulberry silk moth. The silk fibre obtained from the cocoon of this moth is soft, lustrous and elastic.
Natural silk and artificial silk While natural silk is obtained from the cocoon of silkworms and is made of protein, artificial silk, also known as rayon, is obtained from wood pulp and is made using modified plant material cellulose.
Rayon yarn
A soft silk yarn is as strong as a comparable thread of steel!
www.topperlearning.com 3
SCIENCE FIBRE TO FABRIC
From Cocoon to Silk
Similar to sheep, moths are also reared and their cocoons are collected to obtain silk threads.
Rearing
A female silk moth lays hundreds of eggs at a time.
The eggs are stored on cloth or paper and sold to silkworm farmers. The farmers keep these eggs under hygienic and appropriate conditions.
The eggs are warmed to a suitable temperature for larvae to hatch from eggs. The larvae feed on mulberry leaves kept in clean bamboo trays and increase enormously in size.
After 25-30 days, the caterpillars are moved to a tiny chamber of bamboo in the tray to spin cocoons. Small racks or twigs are provided in the trays for cocoons to get attached.
The caterpillar or silkworm spins the cocoon inside which develops the silk moth.
www.topperlearning.com 4
SCIENCE FIBRE TO FABRIC
Processing
The cocoons are kept under the sun or boiled or exposed to steam.
The silk fibres separate out.
This process of taking out threads from the cocoon to be used as silk is called reeling the silk. Special machines are used for reeling which unwind the threads or fibres of silk from the cocoon.
Silk fibres are then spun into silk threads, which are woven into silk cloth by weavers.
www.topperlearning.com 5