Silk- The Basics

Silk in History
For thousands of years silk has been a highly esteemed fabric. It was invented some 5,000 years ago in China, and for about the first 2,000 of those years the secret of producing silk was guarded and remained in China. Finally silkworm eggs and the knowledge of how to produce this textile were smuggled out of China and spread to many places around the globe. Silkworms are actually domesticated insects, and their scientific name is Bombyx mori, sometimes shortened to B. mori. They no longer live naturally in the wild at all, and they only exist to produce silk. If people did not keep them alive for silk production, they would simply disappear. They eat nothing but the leaves of mulberry trees (or substances made from mulberry leaves). When the worms are in their caterpillar stage they are mulberry leaf eating machines. After an enormous growth spurt they extrude a chemical to make a cocoon, and this hardens quickly when exposed to air and turns into silk fiber. The silk worms work for 2-3 days and produce one long strand of silk fiber normally about 400-600 meters in length which makes a cocoon that protects the pupa while it is in the process of metamorphosis into a moth. Silk production unravels this strand and combines it with many others to form the fabric we know as silk. It is interesting to note that most of the pupa are killed in the production process, and only enough moths are born to lay eggs for the next generation of caterpillars.


Silk Properties
Silk has many remarkable properties. It is light in weight and when used in clothing can keep one cool in summer and surprisingly warm in winter. Silk is sometimes used as a liner in winter garments. Silk is very flexible and will return to its original shape without a lot of wrinkling. It can be stretched by as much as 20-25% and return to its original condition. In particular silk takes well to both natural and synthetic dyes, and that is why it is used in colorful parts of the wardrobe such as silk scarves for women and neck ties for men. Taking silk scarves along when traveling is a good way for women to stretch their wardrobes and carry less clothing. That is, a different colored silk scarf can make the same outfit look different.


Wild Silk
There is a certain amount of production of silk made from caterpillars other than B. mori, and India is the leader in this area. This production is small and uneven, however, because the caterpillars cannot be domesticated like B. mori, and the cocoons need to be found in the wild. Also, with B. mori numerous generations can be produced in a year using heating, lighting and other techniques, whereas with the wild silkworms there can only be one generation each year. The silk made from wild silkworms is said to be a bit more rough than the silk made from B. mori.


Conclusion
Silk has a fascinating history, and in the heyday of silk production hundreds of thousands of people around the world earned at least part of their incomes from some facet of the silk industry. Since synthetic fibers like nylon and especially rayon were invented, the demand for silk has dropped a good deal, but there will always be some demand for the real thing.

Walt Ballenberger is webmaster for Silk Scarf a blog with tons of information about silk in general and silk scarves in particular. Visit that site and our companion site, Hand Painted Silk Scarf.