Silk worms and mulberry leaves in Suzhou, China

Silk worms and mulberry leaves in Suzhou, China (Photo credit: Wikipedia)

Since it was first discovered in China an estimated 5000 years ago, silk has been associated with luxury, wealth and success. The usages of silk are extensive and so are its properties: silk clothing will keep you warm in winter while cold in summer, it feels soft and smooth without feeling slippery and it can absorb moisture of up to 30% of its own weight without feeling damp. Being the most expensive of fibres, it currently makes up less than 0,2% of the global textile market.

What many consumers might be unaware of, is that silk is in fact an animal fibre. The fibre is gained from silk worms and involves their killing in conventional production. Most domesticated silk worms feed on mulberry tree leaves for about 30 days and need to go through the process of molting four times within this period. Industrial rearing of silk worms is executed by keeping the caterpillars inside and covering them with chopped mulberry leaves several times a day. They then spin a cocoon about the size of a quail egg and emerge as a butterfly by biting a hole into the cocoon.To avoid the damage of the precious cocoon, labourers will ensure that the silk fibre gets reeled off before the moth has a chance to emerge. Therefore, the cocoons are exposed to hot water or steam until the fibre can be unraveled. In blunt terms, the moth is essentially burnt to death.

Domesticated silk worms have become dependent on humans and are no longer capable of surviving in the wild. They feed only on mulberry leaves and are extremely sensitive to bacteria which is why they are raised inside silk worm farms under constant temperature and humidity. To make the worms and therefore the cocoons grow larger, they are fed growth enhancing hormones. The mulberry trees that provide their sole nourishment will usually be treated with chemical fertilizers.

The film of the company Silkbody shows the silk supply chain from raising silk worms to the production of silk garments:

Although the continuous filament gained from a cocoon is very long, it is also extremely thin and needs to be reeled together with the filaments of 7 other cocoons to give the evolving silk thread the strength and durability required for textile production. The amount of silk worms needed to produce 1kg of raw silk can be up to 15 000, depending on their size.

It is no surprise that animal activists and organisations like PETA criticize silk production, as animals are being killed in order to attain a luxurious product for humans; a process which could be compared to fur production. It yet has to be proven if insects are capable of feeling pain, but either way the production causes the death of a vast amount of small creatures.

Silk filaments unraveled from silk cocoons; Ha...

Silk filaments unraveled from silk cocoons; Hadosan, Urgüp, Cappadocia, Turkey. (Photo credit: Wikipedia)

However, there are alternatives to conventional silk. One of them is Organic Fair Trade silk, where mulberry trees are grown organically on less productive land using bio-dynamic farming methods. Monocultures are avoided and thus biodiversity can be retained. As more manual labour is needed for this type of farming, it has a positive effect on the high unemployment rate in rural areas of China, which is the biggest silk producer in the world. Fixed prices and supply chains ensure economic stability and higher living standards for the farmers. Silk worms will benefit from better food and will not be fed hormones or antibiotics, however they will eventually be killed to unravel the silk.

A more peaceful alternative to this is the non-violent so called Ahimsa Silk or “Peace Silk”, thought up by handloom technologist Kusuma Rajaiah. He was inspired by Mahatma Gandhi‘s philosophy of non violence and respect towards all life. Ahimsa Silk does not require the cocoons to be boiled. Instead the moths are left to emerge before the silk filament gets unraveled. Due to the damaged cocoons, shorter threads evolve which need to be spun. To retain a smooth silk texture, this technology is costlier than that of simply unraveling a continuous silk thread.

And there is even a vegan silk product that does not involve any animals at all. Cactus Silk, also known as Vegetable Silk or Agave Silk, is produced in Morocco by soaking specific cactus leaves in water and hand-spinning the filaments to a fine thread which is then dyed and woven to a highly elastic and shiny silk-resembling fabric.

It is yet to be observed if and how these alternatives to conventional silk will work out for the consumer but it’s good to see organisations taking some steps forward.

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