Thursday, September 1, 2016

Spider silk

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Spider silk

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In 2012 the V & A exhibited an embroidered cape and a four-metre long brocaded piece created using silk from female Golden Orb spiders.
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The spiders are a member of the Nephila madagascariensis family, which are prevalent in tropical countries. The tiny creatures that are small enough to fit on the palm of a human hand, are almost blind, which means they have no idea of how beautiful their silk is. To catch their prey they rely on their sense of touch to feel the vibrations of any prey that gets caught in the web. The beautiful golden webs that can be found on telephone and electric wires are sometimes so big, that they stretch over entire roadways.
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Researchers have long been intrigued by the unique properties of spider silk, which is stronger than steel or Kevlar but far more flexible, stretching up to 40 percent of its normal length without breaking. Unfortunately, spider silk is extremely hard to mass produce, unlike silk worms, which are easy to raise in captivity, spiders kill each other when housed together. Scientists are researching ways to replicate the tensile properties of spider silk and apply it to all sorts of areas in medicine and industry.
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Several groups have tried inserting spider genes into bacteria (or even cows and goats) to produce silk, but so far, the attempts have been only moderately successful. Part of the reason it is so hard to generate spider silk in a laboratory is that it starts out as a liquid protein that is produced by a special gland in the spider’s abdomen. Using their spinnerets, spiders apply a physical force to rearrange the protein’s molecular structure and turn it into solid silk.
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Simon Peers, an Englishman who has lived in Madagascar for more than 20 years came up with the idea of weaving spider silk after learning about the French missionary Jacob Paul Camboué, who worked with spiders in Madagascar during the 1880s and 1890s. Camboué built a small, hand-driven machine to extract silk from up to 24 spiders at once, without harming them.
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Father Comboué and a M. Nogué started a spider silk fabric industry in Madagascar and exhibited “a complete set of bed hangings” at the Paris Exposition of 1898. That fabric has since been lost, but the exhibition brought them some attention.
“It should be said that the female halabe allows herself to be relieved of her silken store with exemplary docility and this in spite of the fact that she is distinguished for her ferocity; her usual treatment of the males who pay her court is to eat them and she feasts without compunction on members of her own sex weaker than herself. M Nogue’s apparatus consists of a sort of stocks arranged to pin down on their backs a dozen spiders. The spiders accept this imprisonment with resignation and lie perfectly quiet while the silken thread issuing from their bodies is rapidly wound on to a reel by means of a cleverly devised machine worked by hand.” — Great Britain Board of Trade Journal
“The first experiments of Father Comboné were made in the simplest manner. The spiders were imprisoned in match boxes and by slightly compressing the abdomen he managed to extract and wind upon a little reel turned by hand it thread that sometimes attained a length of 500 yards… it is to the ingenuity of M. Nogue, one of the sub directors, that we owe the apparatus which permits the thread to be wound mechanically and to be twisted and doubled in the quickest and most practical manner. This is done by means of a curious little machine, not easy to describe, in which the spiders are imprisoned by the throat while undergoing the operation. Young Malagasy girls go daily to a park near the school to gather three or four hundred spiders which they carry in osier baskets with wooden covers to be divested of their webs… Generally after having submitted to the reeling operation the spiders are put back in the park for a couple of weeks… [The silk’s] color when first spun is a beautiful gold and it requires no carding or preparation of any sort before being woven. Will this be the silk of the future?” — The Literary Digest
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To obtain the silk dozens of spider handlers were hired by Peers and Godley to collect wild arachnids and carefully harness them to the silk-extraction machine. Because the spiders only produce silk during the rainy season, workers collected all the spiders between October and June. The silk was extracted from 24 spiders at a time by trained handlers and they were returned to the wild at the end of each day where it takes them about a week to regenerate their silk. It took 80 people five years to collect enough silk for the brocaded textile and over four years to develop the textile.
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The job of producing the silk from these spiders is extremely labour intensive, which is what makes the textile highly valuable and rare indeed, it is the only large piece of cloth made from natural spider silk existing in the world today. The cape, embroidered with images of spiders, plants and flowers took over 6,000 hours to complete.
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