the silk process

the 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.

the silkworm
after a brief incubation period, the eggs hatch into larvae.  for the next 20 to 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
the silkworms are placed on wooden racks that are sectioned with cardboard and 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. 

the 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 hold 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!

other natural fibers are cleaned, carded, combed and spun.  silk is reeled.  this is done by soaking the hot 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 yarns. 

finally, 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
the use of silk is not limited to the textile industry.  it can be found in a 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.