How is Silk Made?

Most of us are most familiar with silk after it has been woven into fabrics. Silk fabric is well known for not only its beauty, but also its incredible insulating properties and strength. Silk itself, though, is a filament that is secreted by silkworms. Despite their name, "silkworms" are not actually worms at all, but rather are Bombyx mori caterpillars. These are the caterpillars of the silk moth and they are used in the production of silk.

The process of manufacturing silk is complicated and rather tedious. Not only that, but it requires a large amount of work to produce even the smallest amount of silk fiber, which is why silk is one of the more expensive fabrics on the market.

Silk production is done on silk farms and begins when a female moth lays her eggs. Each moth lays hundreds of eggs which are incubated until they hatch grow into caterpillars, or "silkworms". The caterpillars are kept warm and fed for about 4-6 weeks until they have grown enough to pupate. It is during this phase of the caterpillar's life that silk production takes place.

Each caterpillar attaches itself to a branch and spins a cocoon. To make their cocoon, the caterpillars excrete a continuous thread of fluid that is high in protein. This thread is wound around and around to form the cocoon where the caterpillar can mature and grow into a moth. However, most caterpillars don't make it past this point of their lives since this is the stage at which silk is harvested.

Some of the caterpillars are allowed to continue their lives and grow into moths to continue the lifecycle and lay more eggs. The other caterpillars, however, are not so lucky. The cocoons that are to be harvested for silk are first heated to kill the caterpillar inside them.

The cocoons are held together by a gooey substance called sericin (also known as silk gum). To separate the silk fibers, the cocoons are soaked in both hot and cold water to soften the sericin. Once the sericin has been softened, the silk fibers are unwound to produce a continuous thread.

A single thread of silk fiber is too fine to be used for commercial use, so anywhere from three to ten strands of silk filament are combined to form a single thread of silk. These silk threads are then wound onto wheels and distributed around the world to be turned into silk fabric.

Silk production began in China where silk was manufactured and exported all over Europe. The Chinese kept the process of making silk a secret for thousands of years until eventually eggs of the silkworm were smuggled out of the country allowing production of silk to begin in the Western part of the world. Despite the fact that China no longer had a monopoly on the silk market, the cost of silk did not come down because the process of manufacturing it remained just as time and labor intensive in the West as well.

Today a wide range of silk textiles are available. Silk can either be treated to be incredibly smooth and soft, or can be left raw depending upon the type of fabric that is to be made.