Silky Stylings

Five thousand years ago, when modern forms of writing had not yet been invented and Egyptian hieroglyphics were just developing, some farmer or worker or emperor of China discovered silk making. I wonder what induced that person to look in the mulberry bushes, pick through the tiny silk worm cocoons, and spin them into thread.

Mulberry bushes at Angkor d' Artisans

Silk worms; moths; cocoons

Silk is something we take for granted, now. It is another fabric that we can pick up in markets, stores, and boutiques. We line our purses, wrap our necks, and clothe ourselves in dresses and shirts all made of silk. We had no idea how much labor goes into producing a small silk scarf until we visited Artisans d'Angkor in Siem Reap. a small silk scarf until we visited Artisans d'Angkor in Siem Reap.

 Cocoons

The silk moth lays about 500 eggs in a period of four to six days and then dies.  The eggs grow into small worms which became adults in about 20 days.  According to Wikipedia, in order to produce 2 pounds of silk, 3000 silkworms need to eat 230 pounds of mulberry leaves.  The silk worms spin cocoons to turn into moths.  About 75% of the cocoons are used in the silk weaving process and the remaining 25% hatch from the cocoons into moths to produce more eggs.

Cocoons ready to be boiled

The workers boil the cocoons with the live moths inside.  Frankly, I find this disgusting. I know that they are insects, it is questionable whether they can feel pain, and most people don't care if they live or die, but it seems wrong to me to boil an insect alive in the name of fashion.  But, maybe I am just being overly sensitive.  (Apparently, there is a type of silk promoted by Mahatma Gandhi called Ahimsa Silk made from cocoons in which the pupae have been extracted or have naturally flown away.)

Rough silk threads extracted from boiled cocoons

A woman sits with a hand crank all day long to extract the rough silk threads from the boiled cocoons which are then dyed using natural and artificial dyes.  The women spin the silk into even thinner fibers until they glisten and glimmer like webbing from a spider.

Spinning raw silk into thin fibers

The women then convert the silk threads into amazing designs which is then woven into scarves, ties, and other fabrics with a loom.  Amazingly, the women don't listen to music or watch television while performing these wholly monotonous jobs.

Spools of silk thread

We also saw no men working in the silk factory; perhaps silk weaving is traditionally considered "woman's work."  (In the same regard, we never saw any female tuk tuk drivers.)  These women work long hours and come from nearby villages to produce the beautiful products we found at the end of the tour.

Weaving silk design with a loom

Though we purchased nothing at Artisans d'Angkor, we have gained a newfound appreciation for this labor-intensive and beautiful material.

Unravelling the Secrets of Silk Production

I get the sense here that we are not too far out from making silk without involving a lot of silkworms. We are getting into critical details here and it appears that it practically self assembles in a two phase process that is surely tricky but no more so than many other manufacturing processes.
It would be neat to produce a synthetic product identical to the natural product. Silk is generally superior to most fiber and cheap supply is a good start. This also suggests how to tweak the process to achieve and sustain best quality.
Again the natural world is feeling the full press of modern research numbers as never before. Few such secrets will remain uncovered and that is great.

Unravelling the secrets of silk production,Oct 11, 2010

    The secrets behind the mighty strength of silk could be unravelled by neutron-scattering experiments being carried out in France. Early results have revealed that silk worms spin their silky threads in a process that seems completely counterintuitive to what is expected. On a domestic note, the findings provide some practical tips for anyone wondering how to wash their silk products.
    For such an elegant material, silk is incredibly durable, possessing a tensile strength comparable with steel. These properties combine to make silk a highly desirable product. But despite being ubiquitous in luxury textiles throughout the centuries, the process of silk formation inside the body of silk worms has remained something of a mystery, with different scientists proposing varying explanations.
    One of the practical limitations when studying silk is that at any given time each silk worm has only minute amounts of silk's precursor proteins inside its body. So any scientific programme to study silk requires the upkeep of large numbers of silk worms followed by the careful extraction of silk samples. Given these difficulties, previous silk studies have used "regenerated" silk proteins, obtained by breaking down silk worm cocoons with high salt concentrations then mixing samples.

Native silk

In this research, a team led by Cedric Dicko of the University of Oxford has for the first time studied the production of pure silk, extracted in small quantities from silk worms. Using a series of small angle neutron-scattering experiments at the Institut Laue-Langevin (ILL), the team was able to hone in on relatively small samples of the large biological molecules that form silk.
    Dicko's team discovered that proteins are abundant inside the worm, with concentrations of up to 400 mg/ml. Unusually for this concentration, the proteins showed very little interaction, instead forming a compact helical structure with a radius of gyration of 90 nm. However, the situation changed as the researchers diluted the silk solution with water, which caused the proteins to unfold to 130 nm and start to combine into the ordered filaments of silk.
    "This is an extraordinarily high concentration for the proteins to remain stably dispersed throughout the solution," says Dicko. "Even stranger, as the concentration drops the proteins begin to expand and flow, until they eventually clump together – this is the reverse of what we'd expected."

Saving silk shirts

The finding that water plays such a key role in giving silk its strength has implications for those in possession of silk products. "Dry-cleaning silks can strip away the moisture and weaken the fibres in silk garments, leaving them more likely to get damaged," says Phil Callow, one of the researchers, based full-time at the ILL. Callow provides reassurance, however, that if one were to make the mistake of dry-cleaning a silk shirt, they should be able to return it to its original condition by steaming it gently.
    Callow explained that neutrons were used to examine silk because they offer advantages over other diffraction experiments, such as X-rays, which can damage the samples under study. He revealed that Dicko is set to return to the ILL in December to continue this research by investigating the effects of temperature variation on silk production.

The latest findings are described in a paper in Soft Matter.

About the author
James Dacey is a reporter for physicsworld.com