eNewsletter
May 2006

Different types of silk

I have talked about silk in previous newsletters. This month, I want to talk about different types of silk and its production. Silk is produced by silkworms, which are not actually worms but moth larvae or caterpillars. Silk is a valuable fiber because its production is labor intensive.

Silk was first discovered in China and was introduced to Europe in the sixth century. Since it was highly prized, trading started between Europe and China via the Silk Road, which was named after its most valuable commodity.

There are five major types of silk worm:

Mulberry worm (Bombyx mori) feeds on mulberry leaves and produces the best silk available.
Tasar (Tussah) mainly feeds on Asan and Arjun plants. The silk it produces is not as lustrous as the mulberry silk.
Oak Tasar feeds on oak leaves and is similar to Tussah silk.
Eri is a silkworm that feeds on castor leaves, producing open-ended cocoons. The silk produced is mainly used for wraps for tribal people in India.
Muga silkworm feeds on the fragrant leaves of Som and Soalu plants. Its silk is highly valued and is used for producing Saris in India.

The Bombyx mori silkworm, which is most commonly used in silk production, is a native of China. Bombyx mori feeds only on mulberry leaves. It has been domesticated for centuries and cannot be found in the wild anymore.

Silk production begins with hatching the eggs of silkworm that happens when the mulberry leaves are ready for consumption. As the eggs hatch, the larvae start feeding for about 6 weeks in which time they feed about 50,000 times of their size in plant material. During this time, the larvae shed their skin four times. When the silkworms are ready to make their cocoon, they stop feeding. They attach themselves to branches, aluminum compartments or whatever else available and make their cocoons within 3 to 8 days. The cocoon is silk fiber, which is between 328 yd (300 m) to 984 yd (900 m) long. Silk is the saliva of the silkworm that hardens as it comes into contact with air. If the cocoons are left alone, within a few days the grown moths will make holes in their cocoons and emerge into the world to mate and produce the next generation of larvae. Instead, the cocoons are placed in hot water where they soften and the larvae die. The silk filaments are reeled off to make yarn, which is ready for dyeing and spinning.

Today, silk is combined with wool and cotton to produce new combination fabrics. Silk is soft and has a natural sheen. It is moisture-absorbent, dyes easily, and is cool to the touch in summer and warm in winter. Since it is hard to produce and expensive for most people, more economical options are available, such as acrylic fibers and soy silk. However, nothing comes close to real silk produced in nature. For more information checkout www.wormspit.com.

Nazanin S. Fard

Needlecraft University

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