Silk is beautiful, highly demanded and expensive. And most people know that it is produced by silkworms.
But do you know how exactly?
You’ll be surprised that still today the only reasonable way to produce silk in mass quantities is by killing the thing that made it.
Silk has been a highly prized and demanded fabric since it was first harvested thousands of years ago. And despite the technological advances in production, it is still produced the same way.
Worms in the production line
The process of silk production is known as sericulture.
During its 3 to 8 day pupation period, the silkworm secretes fibroin, a sticky liquid protein, from its salivary glands.
Next, the silkworm secretes sericin, a bonding agent, from two other glands to hold the two filaments together. While constructing its cocoon, the silkworm will twist in a figure-8 motion about 300,000 times and produce around 1 km of filament.
This entire production takes a mere 72 hours. During this time they produce between 500-1200 silken threads. But to get the billions of cocoons necessary to have a viable silk industry, the worms are being cultivated.
Farm workers place the 500 plus eggs upon the strips of paper or cloth, until the following spring, when the tiny worms emerge. Additionally, the silkworms lay, at minimum, 500 eggs each spring, thereby increasing the number of workers in the production line.
Because of this natural production, recent trends have popularised silk pillows. It has been suggested that they might be able to help with breakouts and wrinkles. The bedding specialists from Tow and Line say silk pillowcases can be thought of as skin care supplements.
They say, “there is not enough research to support it as the solution but they are able to provide some benefit. Silk pillowcases can be more comfortable and easier on the hair. When it comes to your skin, it could help with the hydration and pore clogging.”
Once the eggs are hatched, they are transported to trays brimming with the worms’ favourite white mulberry leaves. Although a few other plants are fed to silkworms, the mulberry has always been associated with its production. In fact, the lesser quality silk is made from silkworms that eat Osage orange and lettuce.
After about 6 weeks of constant eating, the silkworm grows into 8 centimetres in length and weighs nearly 10 000 times it did when it hatched and begins to work on spinning its own grave.
The home construction specialists DC Cladding say people choose silk materials in their home decor more and more often.
They say, “it is a luxurious fabric, it looks elegant, natural with a lustrous and smooth texture. Owing to its royal look and feel, silk is one of the most sought-after fabrics to be used in home interiors. However, people should keep in mind that it is very delicate and prone to stains.”
Spinning the wheel
Further down the silk production process, since hatching from the cocoon destroys the thread, to harvest the silk, the cocoon is placed in either boiling water, or blasted with steam or hot air, all processes that kill the pupae.
Less lethal methods were tried in the past, such as pulling the silk as the worms spun it, but the worms resisted and bit off the filaments.
The empty cocoons are then placed in warm water which softens the gum binding the filaments together. Then, the next step of the production is unraveling several cocoons and winding the filament onto a reel into a “single” thread of silk.
Today, China leads the world in silk production, responsible for about 58,000 tons each year or about 74% of the world’s supply of raw silk. Not wasted, in many places the leftover dead silkworms are seasoned, boiled, fried and eaten.
Save the humble silkworm
Some kind researchers have recently discovered a method to harvest long filaments without killing the creature. They noticed that when the caterpillar gets injured, it goes into paralysis in order to give itself time to heal.
The scientists found a way of extracting the biochemical and injecting it into healthy worms, which causes partial paralysis. In this state, the worm is unable to bite off the thread, as it would normally, thus not damaging it.
Since hand-injecting billions of silkworms is beyond unrealistic, to turn this process into a commercial reality, the researchers are looking into ways to genetically modify silkworms so that the paralysis can be triggered by manufacturers “on demand.”