delanceyplace.com 10/25/11 - how to make silk

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In today's excerpt - silk making was so critical to the wealth and power of China that extreme measures were taken to guard its secrets, and it was a capital crime to spread those secrets beyond the imperial domain. The moths used to make the finest quality silk are blind, flightless, and can only live in captivity:

"Today's methods [of making silk] are not all that different from those pioneered by artisans thousands of years ago. It all begins with the cultivation of silkworms—a little white caterpillar. ... For thousands of years, silk farmers, first in China and then around the world, have raised silkworms and harvested their silk.

"Both wild and domesticated silk moths produce silk, but the best-quality filaments come from the domesticated silkworm moth, Bombyx mori. Descended from a species native to China, these silk moths are helpless: they are blind, flightless, and can only live in captivity.

"[After] adult silk moths mate, the female soon lays about five hundred tiny eggs—and then she dies. After about ten to twelve days, a minuscule caterpillar hatches out of each egg. The little caterpillars grow quickly as they feed on mulberry leaves, multiplying their weight 10,000 times in only one month. As a result, they continually 'outgrow' their whitish gray skin and shed it three or four times before they reach full size.

"The mature caterpillar soon spins a silk cocoon around itself and, once safely inside, begins its transformation into a pupa. If left to its own devices, the pupa emerges from its cocoon as a moth and begins the life cycle all over again. In silk cultivation, however, the farmers interrupt the natural cycle by collecting the cocoons before the moths are ready to hatch. They unwind the cocoons into silk threads, which are then woven into cloth. ...

"The natural history of silk is interesting in its simplicity. The silk moth is a unique insect because it cannot survive outside of human husbandry. Left alone to the wilds, even in delicate temperate climates, the moths and their caterpillars will die if exposed to the natural elements. They are also extremely susceptible to changes in temperature and humidity. People who raise silkworms traditionally don't like visitors and don't cook heavily scented foods or even smoke cigarettes in their homes. The doors of their houses are usually posted with paper signs announcing when the worms are in a fragile stage.

"After a silkworm spins its cocoon over the course of two to three days, the cocoons are harvested. Only a few moths are allowed to emerge and reproduce to provide the next generation. The individual cocoons are processed by immersion in scalding water, killing the metamorphosing moth and relaxing the single silk thread that comprises the entire cocoon so it can be drawn from the boiling water.

"Silk itself is a complex protein, which when secreted is triangular in cross section. This structure causes reflected light to be broken up, giving silk its unique shimmering property. Each cocoon can provide about a mile-long silk filament; however, it is so fine that it takes up to five hundred cocoons to make a six-ounce silk robe. Although other kinds of "silk" from different species of moths (and even spiders) have been used to make fabrics, practically all silk fabric ever produced comes from this single domestic species."