Silk is a fabric like no other. Historically, its unparalleled beauty, durability and comfort have been appreciated by the ranks of nobility – Roman and Arab aristocrats mostly. The rarity of the fabric made it all the more precious.
For more than a thousand yearshow that silk was produced remained a well-kept secret kept by ancient China, which was reluctant to give up its monopoly. The fabric was one of the most prized commodities traveling westward along the vast network known as the silk road. In that time silk was worth as much as its weight in gold and was sometimes used as a form of currency.
What is it about silk that has fascinated mankind for thousands of years, making it a sought after status symbol today?
How silk is made
Unlike cotton or hemp, which are made from plant fibers, silk is a protein fiber made from the saliva of silkworms, a tiny insect scientifically known as the Bombyx mori moth.
The process of harvesting these cocoons for silk is called sericulture, and has been around for thousands of years. In essence, farmers create an artificial environment for the moths to lay eggs on special paper, where they hatch and become larvae. They are then fed a steady diet of mulberry leaves, and after about 35 days of growing and multiplying in size, they are ready to make their cocoon. Once their cocoon is complete, the silkworm process traditionally involves killing the silkworm by live cooking or steaming.
This cooking step also makes a natural chemical known as sericin bone, which would otherwise harden the cocoons, resulting in a substance that is not as soft. This is followed by reeling, where cocoons are unraveled and become one continuous thread can be hundreds of meters long. Multiple long silk strands are then intertwined to make silk thread. Ultimately, that silk thread is woven into a fabric for commercial use.
This process of harvesting the eggs, breeding silkworms, and killing them in their cocoons is done continuously to keep up with the demand for silk. Domesticated Bombyx mori moths have lost and have lost their ability to fly through selective breeding atrophied wings. As a result, silk farming practices have been criticized in recent years and animal rights groups such as PETA have called for a ban on silk. Some estimates say it takes about 1 pound of silk to be produced 2,000 to 3,000 silkworms are killed.
In some silk producing countries, such as China, the boiled silkworms are ate after harvesting the cocoon. While eating silkworms means less bio-waste and provides some nutritional value, only a small percentage of silkworms in the fabric industry are actually consumed. However, eat insects could become more common in the future, as the global demand for sustainable animal food increases.
In addition, there is another way to harvest silk without harming or killing silkworms. This method was developed in India and produces what is known as ahimsa silk. Sometimes it is called ethical side, peace side or cruelty free side. While the production of ahimsa silk includes much of the traditional silk culture practices, harvesting does not involve killing the worms. Instead, the worms are allowed to emerge from their cocoons, or sometimes the cocoons are cut open and the pupae are tilted out.
When they hatch, the pupae spend an additional 7-10 days in the cocoon, which begins to harden. This tends to result in lower yields of silk and threads breaking into multiple strands, resulting in a rougher fabric. Because ahimsa silk is more difficult to produce, it is usually more expensive than its conventionally grown counterpart. Still, it is gaining popularity and is seen as a viable alternative in the fashion industry.
Some fashion labels now have dumped silk, but the demand for the luxury fabric has not been completely resolved. One of the reasons silk is so prized is its ability to seemingly change color and hues when viewed in different lighting. This is due to his fibroin proteins, the triangular-shaped molecules found in the material. Its molecular structure allows light to refract at unique angles, giving silk its unmistakable shine and eye-catching appearance.
Silk also has great potential in the biomedical field. Because it is strong and antimicrobial, silk has a long history in medicine. Recently it has even been explored for its potential in regeneration of the skin.