The Silk Process
process begins with the silk moth, which lays hundreds of tiny eggs
about the size of a
pinhead. The eggs are carefully examined and
diseased eggs are discarded. The remaining eggs are divided into two
groups, one for reproduction and one for production of cocoons. Once
they pass inspection, the
eggs are put into cold storage for 6 to 10 months
until the mulberry trees begin to bud.
a brief incubation period, the eggs hatch into larvae. For the next 20
30 days, the larvae live in a carefully controlled
environment and eat a special diet of cleaned, chopped mulberry leaves. During this time, they grow rapidly, shed their skins four times, and
mature into grayish-white
caterpillars about 3 to 4 inches long, called
silkworms. The silkworms are ravenous, but quite picky: the mulberry
leaves must be clean, dry and the same age as the silkworms themselves.
if conditions are less than
perfect, the silkworm will produce inferior silk or
none at all.
When the silkworm has finished growing, it stops eating and begins to spin a cocoon to protect it during
the final stage of the cycle, transformation into a moth.
The Silk Cocoon
silkworms are placed on wooden racks that are sectioned with cardboard
stacked about ten rows high - just like a high-rise
apartment for caterpillars. Each silkworm has its own compartment to
spin its cocoon, which helps to keep the cocoons from getting tangled.
cocoon is really an oval shell or casing about an inch long. The
silkworm extrudes a syrupy
fluid from two silk glands in its head. The fluid
instantly hardens into two silk filaments called brin, which are held
together by a sticky substance, called sericin, secreted from another
set of glands. The double
filament forms a single strand, called bave. The
silkworm moves its head from side to side in a figure-eight motion,
crossing the strand to build layer after layer of the cocoon from the
outside in. It spins
continuously for 24 to 72 hours, shrinking in size
as it goes, until the cocoon is done.
If nature were allowed totake its course, a soft, fuzzy, cream-colored moth would break out of the
cocoon in about twelve days by emitting a liquid to dissolve a hole in the silk.
Unfortunately for the new moth, silk is more valuable when the long filament is not broken. The
finished cocoon is refrigerated to stifle the moth and prevent it from damaging the silk.
A single, unbroken cocoon yields from 1,600 feet to more than a mile of
continuous filament, in contrast
to the short fibers of cotton, wool, linen and other
natural fibers. The length of silk makes it possible to produce
dupioni unlike anything else in existence today!
natural fibers are cleaned, carded, combed and spun. Silk is reeled. This is done by
soaking the cocoons in hot water to soften the
sericin and loosen the silk. The surface of each cocoon is lightly
brushed to find the end of the filament. Several of these exceedingly
fine strands are collected
and reeled into a single, untwisted thread, held
together by the sericin. Two to ten cocoons may be used to form this
single strand of reeled, raw silk.
The next step is called "throwing," from the anglo-saxon word thraw,
meaning to twist
or spin. A throwster sorts the skeins of raw silk
for quality. Then the reeled silk is grouped and twisted into different
types of thread, commonly called yarns, used to weave fabric. Two or
more strands of
reeled silk are used to form the different silk
the silk is degummed of part or all of its sericin, usually by boiling
the yarn or fabric in a
soapy solution. The more sericin boiled off, the
better quality the silk. When the silk is degummed, it becomes much
softer, more lustrous and generally more desirable.
Once it has been degummed, the whitened silk can be dyed or printed. Cultivated silk dyes
especially well, so fabrics are often brightly colored.
Other Silk Uses
use of silk is not limited to the textile industry. It can be found in
wide variety of other products, including face
powder, cold cream, wigs, dental floss and braces, bicycle tires, tennis
racquet strings, fishing lines, parachutes, hot-air balloons, surgical
sutures and bandages, electrical
insulation and crosshairs in optical instruments.