Yes, yes, yes…I know I’m ending the title with a preposition. But bear with me. I have a sinus headache so I’m not writing at one hundred percent. In fact, this article will be shorter than I originally intended. We’ll stretch silk out to next week, too.
“Mommy? Where does silk come from?”
“A stork carries it and puts it in a basket on our doorstep.”
Wouldn’t that be nice if that were the truth? Unfortunately, the truth is not glamorous and many people have sworn off silk because of it. Don’t read this while eating if you don’t have a strong stomach (don’t say I didn’t warn you).
As we learned last week, sericulture is the production of cultivated silk. Silk begins its life when a silk moth lays eggs on a specially prepared paper. When the eggs hatch, the caterpillars (or larvae) are fed fresh, young mulberry leaves and are as happy as can be. After about 35 days and four moltings, they decide that they really should get their own digs because they’ve outgrown the home place (they are about 10,000 times the size they were when they were hatched), so they start spinning cocoons on specially constructed straw frames that are placed on the silkworm trays (you’d think they would start getting suspicious, no?). They spin their cocoon by moving its head in a figure eight. The silk is produced by two glands and the liquid silk is forced out of the spinnerets (openings) in the silkworm’s head. The silk is coated with sericin, a protective water-soluble gum. When the silk comes in contact with the air, it solidifies. The silkworm is focused on getting this cocoon built and spins about a one mile of filament silk in 2-3 days. Then it sits back, fully encased in the cocoon and waits for the metamorphoses into moth thing to happen.
Only it doesn’t. At least, not for most of them.
Silkworms are usually killed with heat (stifled) before they reach the moth stage.
Silk is the only natural filament fiber. To make a wool thread that can be woven, they have to spin a 
whole bunch of short fibers together to create something long enough to weave. Not so with silk. The silkworm makes our nice long thread for us. After the worm has been stifled, the cocoons are sorted for fiber size, fiber quality or defects, and then brushed to find the outside ends of the filament. After that, several filaments are wound together on a reel (referred to as reeling). Each cocoon gives us approximately 1,000 yards of silk, creating raw silk. Several of these filaments are combined to give us yarn that can be woven (remember, yarn used here is not the same as the yarn you find at the craft store).
Silk noils is also known as silk waste. Remember that the next time you see a silk noils dress being advertised in a fancy-schmancy catalog. Essentially, silk noils is created from cocoons where the filament broke or the moth was allowed to mature. The resulting fiber needs to spun just like any other staple fiber. Spun silk is less expensive, less durable, more likely to pill, and of lower quality than its filament counterpart.
Silk shantung
Wild silk is exactly that…wild. Production of wild silk is not controlled. The silkworms feed on oak and cherry trees in the wild and the cocoons are harvested after the moth has matured. Because the filament is broken, the silk must be used as spun silk. Tussah is the most common type of wild silk; tasar is a wild silk from India. Beware: “Raw silk” is often used incorrectly to describe wild silk.
Finally, Duppioni silk is created when two of those crazy silkworms decide to shack up and spin their cocoons together. The result is that the yarn has a thick-and-thin appearance. It is used to create a linen-like fabric such as shantung.
We’ll finish up our lesson on silk next time.
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