Vacation China – Silk, Part 2- Production
Silk is a filament secreted by the silkworm when spinning its cocoon, and the name for the
threads, yarns and fabrics named from the filament. Most commercial silk is produced by the cultivated silkworm,
Bombyx mori.
Silk
Its Origin, Culture and Manufacture
The Nonotuck Silk Company
Florence Massachusetts
1895
The secret of silk production was a closely guarded Chinese
secret. The penalty of revealing this
secret was punishment by death. Inevitably, the secret was too valuable and
there are several versions in folklore, which describe the lengths smugglers
would go to steal the secret from China to sell it to the West One tells of monks hiding cocoons in their
walking sticks!!
Bombyx mori feeds exclusively on the leaves of various
mulberry trees and spins a thin, white filament. There are several varities of wild silkworms which feed on oak,
cherry and mulberry leaves, but their filament is brown and coarse and 3 times
the thickness of the cultivated.
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| Teaching sample of trays used for feeding. In factories the worms are raised on huge trays fitted with a wire bottom for cleaning of the larvae waste. The wire is then covered with fresh mulberry leaves |
Carefully selected moths lay 500-700 eggs apiece. One ounce of silkworms requires nine tons of
mulberry leaves to reach maturity, their cocoons will produce 12 pounds of silk.
Eggs take 14 days to mature into larvae. The larvae are raised on trays kept in a
temperature-controlled, clean
environment and are fed every 2-3 hours. Fully grown in approximately 5
weeks, they are 70 times their original size.
Their rear silk glands produce an animal protein called fibron which is
activated and sent to silk producing glands.
The silkworms are placed on a bed and enter the pupa stage, enclosing
themselves in a silk filament in an endless series of figure-eights (300,000
times) 1 ½ miles in length.
Eight to nine days the silkworm changes into a moth and must
emerge from the cocoon. To do so it
produces an enzyme to soften the cocoon and produce a hole, from which it
emerges. Since the enzyme is
destructive to silk fibers , the fibers break down from their mile-long
filament into shorter segments of
random length, ruining the silk threads.
(These waste cocoons are used to spin noil, to make various products but
are not suitable for fine silk thread production.) To prevent this, at the factory the cocoons are gassed, boiled or
steamed, killing the silkworm. Of
course, enough moths are allowed to hatch so that egg-laying can continue,
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Moths emerging from cocoons
Note the damage to cocoons |
Intact cocoons. Dead pupa taken from cocoons prior to reeling. Fear not, these are an excellent source of protein and are use in the cosmetic industry.
After drying the cocoon are inspected and graded and sent to
a filature (factory) for reeling..Today, automated reeling machines are
equipped with sensors, allowing for immediate replacement of empty cocoons or
broken filaments. The silk filament is made stronger for weaving by plying,
called throwing, increasing the
twist or adding more strands together.
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| Moi inspecting a n automated reeling and plying machine at the factory. The cocoons are stored in the blue containers at the bottom of the reeler. The plied silk thread is on the spools at the top |
Skeins of silk are formed into bundles (29) and
collected into bales (132#), the amount raw silk is traded for export.
Vintage photo of silk traders examining skeins of silk
