SILK SILK SERICULTURE

Silk is a natural protein fibre, some forms of which can be woven into textiles.proteinfibrewoventextiles The protein fibre of silk is composed mainly of fibroin and produced by certain insect larvae to form cocoons. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity (sericulture). cocoonslarvaemulberrysilkworm Bombyx morisericulture The shimmering appearance of silk is due to the triangular prism-like structure of the silk fibre, which allows silk cloth to refract incoming light at different angles, thus producing different colors.prismangles

Silkworm larvae are fed mulberry leaves, and, after the fourth moult, climb a twig placed near them and spin their silken cocoons.larvaemulberrymoultcocoons This process is achieved by the worm through a dense fluid secreted from its gland structural glands, resulting in the fibre of the cocoon. The silk is a continuous-filament fiber consisting of fibroin protein, secreted from two salivary glands in the head of each larva, and a gum called sericin, which cements the two filaments together.fibroinproteinsalivary glandssericin

The sericin is removed by placing the cocoons in hot water, which frees the silk filaments and readies them for reeling. The immersion in hot water also kills the silkworm pupae. This is known as the degumming process.[4][4] Single filaments are combined to form thread. thread This thread is drawn under tension through several guides and wound onto reels. The threads may be plied together to form yarn. After drying the raw silk is packed according to quality.yarn

Stages of production The silk moth lays eggs. The eggs hatch, and the larvae feed on mulberry leaves. When the silkworms are about 10,000 times heavier than when they hatched, they are now ready to spin a silk cocoon. The silk is produced in two glands in the silkworm's head and then forced out in liquid form through openings called spinnerets. The silk solidifies when it comes in contact with the air.

Continues… The silkworm spins approximately 1 mile of filament and completely encloses itself in a cocoon in about two or three days but due to quality restrictions, the amount of usable silk in each cocoon is small. As a result, 5500 silkworms are required to produce 1 kg of silk. The silk is obtained from the undamaged cocoons by brushing the cocoon to find the outside end of the filament. The silk filaments are then wound on a reel. One cocoon contains approximately 1,000 yards of silk filament. The silk at this stage is known as raw silk. One thread consists of up to 48 individual silk filaments.

sericulture larva larva in mulberry leaves cocoons

Silk reeling

Top Ten Cocoons (Reelable) Producers — 2005 Country Production (Int $1000) Foot n o t e Production (1000 kg) Foot n o t e People's Republic of China 978,013C290,003F India 259,679C77,000F Uzbekistan 57,332C17,000F Brazil 37,097C11,000F Iran 20,235C6,088F Thailand 16,862C5,000F Vietnam 10,117C3,000F Democratic People's Republic of KoreaDemocratic People's Republic of Korea 5,059C1,500F Romania 3,372C1,000F Japan 2,023