Silk: Manufacture

music
ambience: silk reeler, powered by foot treadle whisk – cocoons in solution, treadle, whisk

We’re listening to the sounds of a device that was once used to make silk thread. Modern machinery has replaced this foot-powered treadle, but the process of making silk is essentially the same as it’s been for centuries. And it all starts with a cocoon of a caterpillar known as a silkworm. I’m Jim Metzner, and this is the Pulse of the Planet.

“The cocoon is actually a house for a developing silkworm moth, and that’s called a pupa. So the cocoons are harvested. They’re heated at low temperature to kill the pupa because you can’t cut them open, otherwise you break the silk thread.”

Dr. Michael Wells is a biochemist at the University of Arizona.

“The cocoon is composed of two kinds of protein. One is silk, and the other is called sericin. Sericin serves as like a glue to hold the silk fibers together. In order to spin out the silk threads, you need to get rid of the sericin. And this is accomplished by placing the cocoons in a slightly alkaline solution which desolves the sericin and leaves behind a mat of the silk fibers.”

The apparatus that we’re listening to has at one end of it — a vat of cocoons boiling in solution. Using a brush like tool the operator has teased the end threads from a number of the cocoons, twisted them together, and pulled them through a pulley above the vat. The composite thread is then wound around a turning wheel.

“They’re usually 6 to 8 cocoons – are used to make a single thread. Each cocoon contains enough silk to make about a kilometer long thread. The cocoon itself is only a couple of inches long, but is very tightly packed with silk.”

Pulse of the Planet is presented by the National Science Foundation, with additional support provided by the National Science Foundation, I’m Jim Metzner.

music

Silk: Manufacture

Silk by another name is protein with glue.
Air Date:08/13/2003
Scientist:
Transcript:


music
ambience: silk reeler, powered by foot treadle whisk - cocoons in solution, treadle, whisk

We're listening to the sounds of a device that was once used to make silk thread. Modern machinery has replaced this foot-powered treadle, but the process of making silk is essentially the same as it's been for centuries. And it all starts with a cocoon of a caterpillar known as a silkworm. I'm Jim Metzner, and this is the Pulse of the Planet.

"The cocoon is actually a house for a developing silkworm moth, and that's called a pupa. So the cocoons are harvested. They're heated at low temperature to kill the pupa because you can't cut them open, otherwise you break the silk thread."

Dr. Michael Wells is a biochemist at the University of Arizona.

"The cocoon is composed of two kinds of protein. One is silk, and the other is called sericin. Sericin serves as like a glue to hold the silk fibers together. In order to spin out the silk threads, you need to get rid of the sericin. And this is accomplished by placing the cocoons in a slightly alkaline solution which desolves the sericin and leaves behind a mat of the silk fibers."

The apparatus that we're listening to has at one end of it -- a vat of cocoons boiling in solution. Using a brush like tool the operator has teased the end threads from a number of the cocoons, twisted them together, and pulled them through a pulley above the vat. The composite thread is then wound around a turning wheel.

"They're usually 6 to 8 cocoons - are used to make a single thread. Each cocoon contains enough silk to make about a kilometer long thread. The cocoon itself is only a couple of inches long, but is very tightly packed with silk."

Pulse of the Planet is presented by the National Science Foundation, with additional support provided by the National Science Foundation, I'm Jim Metzner.

music