Material Series VII : Soft Sweet Silk!
I don’t know about you, but when I think of silk, I think soft, luxury, elegant, colourful and also expensive! In this Material Series, we will be looking into if silk is also sustainable!
Where does it come from?
The legend goes that it was a Chinese Empress Xi Lingshi who discovered this beautiful fabric. One fine day in 27th century BCE, the Empress was enjoying a cup of tea beneath the mulberry trees when a cocoon fell into her cup. As the cocoon began to unravel itself, the Empress admired the beauty of the shimmering threads. And so it goes that the young empress invented the reel and loom and began to teach the ladies of her court how to weave silk fabric.
If you dig deep in your memory, you might have heard about the Silk Road which was basically the ancient trade route through Asia, the Middle East, and Europe.
Silk is actually a protein fibre spun from the long threads which make up the inner cocoon of a silkworm. The fibres are in fact saliva, produced by the worm to insulate itself until it is time to transform. The raw silk threads are harvested and then reeled together for commercial use.
Most silk production comes from farming the larvae of the mulberry silkworm Bombyx mori. The mulberry is a hardy tree, resistant to pollution and easy to cultivate. The tree bark has medicinal properties and the fruit can be used as a natural dye or to fill a pie. The leaves of the mulberry will feed the worms and the worms, in turn, can feed the farmers. Pretty circular if you ask me!
You might wonder what happens to the worms in this process, well the bad news is the silkworms are killed during the process of extracting the silk, but the pupae don’t go to waste. They are a rich source of protein, which makes them a popular snack across many Asian countries. The outer-cocoons are also used as fertiliser or to stuff pillows.
The reason why they are killed is that when the moth does get out of the cocoon, it eats his way out destroying part of the precious long silk threads and instead of a thread up to 1,3m you get smaller threads of 10-15cm which are more difficult to handle.
However, it is also possible to find less lethal alternatives to the silk-making process. Ahimsa silk, also known as ‘peace silk’, does allow the moth to get out of the cocoon. Some silks that fall under the Ahimsa umbrella include ‘Eri silk’ and ‘Tussar silk’.
Eri silk uses castor plant-fed domesticated silkworms that aren’t harmed during the production process. Tussar silkworms are truly wild, allowed to leave the cocoon before they are harvested from the forest. These types of silk should be clearly labelled, so don’t be fooled by knock-offs.
Benefits of silk
Silk is a natural fibre which means is biodegradable at the end of its useful life. Always being mindful of the kind of dye which has been used of course.
Silk is often quoted as being as strong as steel, for its weight. The problem is that it is used in very fine fibres and thin fabrics. Such lightweight silk fabrics are prone to wear and are also degraded by exposure to sunlight, as well hot temperatures and the abrasion and twisting that results from laundering.
The silkworms are not the only animal producing silk and research is currently being done in producing alternatives for traditional silk such as Bolt Threads.
Bolt Threads launched its first commercial spider silk or Microsilk. But the company does not use actual spiders in the process, they used the spider's skills as inspiration for their process. The thread is made from yeast, water, and sugar. The raw silk is produced through fermentation, much like brewing beer, except instead of the yeast turning the sugar into alcohol, they turn it into the raw stuff of spider silk. This innovative material is both strong and flexible and could be used in everything from bulletproof vests and flexible bridge suspension ropes.
The less pretty side of silk
A few small downsides to the use of silk.
Chemicals may be used in the cleaning or degumming of the cocoon, so choose your silks carefully.
As usual with all textiles, the dyeing process can be toxic.
If vegan is your thing, I need to disappoint you, traditional silk won’t be for you.
Also, animal cruelty is a bit of an issue, unless you choose the Ahimsa silks.
Often silk requires dry cleaning, so please choose your dry cleaning wisely, or wash it yourself carefully and press with a cold iron under a towel.
Silk production is a very labour intensive process and seen the high prices but low wage production country of origin, it is prone to exploitation as indicated in 2003, Human Rights Watch reported the abuse of child slaves in the Indian silk industry.
Everything considered I would say silk is a good contestant for our sustainable materials list! Natural, biodegradable, renewable, strong, soft, luxurious,…
Just be mindful on the sourcing and how you care for your garments and you will have some beautiful pieces to treasure for a long time!
Want to learn more about some other materials: check out the other articles from the Materials Series here.