Silk

An attractive fabric. The first pheromone ever analyzed chemically (bombykol) comes from silkworms, about half a million of them sacrificed for its discovery by a German professor who once signed a vow of allegiance to Hitler. By luring moths to areas devoid of mates it can be used as an insecticide.

One of the three basic types of weave, satin, is also the name of the fabric but only when the weave is done with silk (or plastic filament), while the same weave made with cotton or any other natural fiber is called a "sateen". The shine is from large areas of uninterrupted threads (unlike in a plain weave which is checkerboarded over/under and maximally scatters the light), and silk's shine in particular comes from each silk thread having flat surfaces since it's shaped like a very long triangular prism with rounded corners. Silk bears a similarity to plastic filaments in its length, a single thread reaching up to 3000 feet, and in some ways its strength: the precursor to ballistic nylon (itself precursor to kevlar) was the bulletproof silk vest, oft donned by gangsters around 1900 and demanding a hefty price.

Likely unknown to the bulletproof vest wearers, there was already metal in the fabric. Silk was sold by weight and at the time there was an entire patent category around methods to produce "weighted silk" by binding metal salts to the silk fibers to make them artificially heavier without noticeably changing other characteristics of the material (like luster or durability). The FTC began regulating this in 1938 after it had reached such ridiculous heights that some product had ten times as much weighting as silk.

Use by the powerful and regulation of its sale are on brand for silk. Sumptuary laws the world over, from ancient Rome to China to England to followers of Islam, have regulated wearing silk whether as moral code, limit on showcasing extravagant wealth, exercise of state authority, or economic policy to lessen trade deficits. Originally it was only accessible to the imperial family in China, where sericulture (raising silkworms) was a national secret responsible for the nation's world monopoly on its most valuable trade commodity for a thousand years. Export of eggs was a capital offense, and it took hundreds of years before the Byzantines smuggled eggs out of China in the 6th century to create the first European-made silk.

Secrecy and deception came in other forms, from unraveling and reweaving traded silk along the supply chain to obscure its origin to secluded factories guarding production techniques like the imperial workshops in China. Many silk textiles bear names of their origins, like damask for the sophisticated weaving techniques in Damascus or taffeta which comes from the Persian word for silk. From chiffon to velvet, damask to moiré, shantung, habutai, charmeuse, taffeta, brocade, and tulle--the range of fabrics first made from silk is vast. Intricate damask weaves look simple by comparison to the fabrics manufactured on the Jacquard loom, a punch-card-programmable weaving machine patented in 1804. For examples of its programmatic capabilities, see a rendering of a portrait of Jacquard himself woven in silk, requiring over 20,000 punch cards for the pattern, or the 58-page prayer book, all silk, encoded by nearly half a million punch cards and shown at the 1889 world's fair. Silk threads are some of the thinnest around, making intricate detail in such programmable weaves possible. Related to the thinness is its weight per length, with its fiber density still used as a standard to this day in the United States via the denier, a unit measuring the weight of 9000 meters of thread (silk has density of around 1 denier).

Jacquard was born in Lyon and less than 30 years after the development of his automated weaving machine came one of the earliest European worker strikes by the silk workers of the same city who rebelled, took control of Lyon, and flew a black flag for the first time which was 50 years later taken up by Louise Michel as a symbol of anarchism. In both cases the unrest was put down by the military, and in the first case the silk workers were forced back to work for the same wages they had rebelled in protest of. Likewise the Perry Expedition by the US Navy sought to open Japan to trade by any means including force in the 1850s. This led to Japanese dominance in the silk trade as Chinese production fell on account of the Taiping Rebellion, though production had been Chinese only in location by that point with over half of it owned by foreign powers. Soon after Japanese silk arriving on the Pacific coast of the United States was rushed to New York on "silk trains" running as fast as humanly possible.

Meanwhile European sericulture was hit with the plague of pébrine which decimated silkworm populations and led to repopulation of European silk production by Japanese egg exports, kept safe from the disease by tight border controls. Pasteur's studies of it led to the discovery of the first microsporidia and the development of the germ theory.

Even when they get to make the cocoon, though, most silkworms never complete their full lifecycle on account of being boiled alive by the humans who raise them. Otherwise they eat their way out of the cocoon which disrupts the fibers and lessens the value of their product. The ones who are allowed to mature only in order to usher in the next generation become moths which can no longer fly on account of millennia of domestication (like domesticated corn being unable to seed, and unlike wild silk moths which can still fly) and require human assistance with their mating.

On hatching, the worms eat almost continually aside from short naps, allowing them to grow to 10,000 times their weight within 35 days. When they're finally ready to make a cocoon, they work for over three days straight spinning it out of two glands making strands which are glued together with a compound called sericin (which seems not unlike the lignin holding together tensile cellulose). The sericin is usually boiled off in production (degumming) and cocoons unwound and spun together (reeling). Methods in the past 20 years show that it's possible to dissolve the silk proteins in "chaotropic salts" to make a solution similar to that in the silkworm glands which can be recrystallized, allowing for production after the worms hatch for a type of "ahimsa" silk named after the word for nonviolence and the same as occurs in Gandhi's writing, who opposed the production of silk on account of the boiled worms.

Modern methods have begun using silk for scaffolding transplant tissues because the protein (fibroin) is perfectly amenable to human hosts, first noted in ancient medicine's use of silk sutures which are still in use today. Other medical applications include silk based drug delivery, from implants to transdermal microneedles to injectable gels and microspheres.

Science is still trying to crack the production of spider silk, most recently by making genetically modified silkworms with spider DNA, leading to the production of very strong silk fibers. Spider silk has the highest strength to weight ratio of any known material (seven times that of steel) and is of particular interest to materials scientists. Other material properties of commercial silk include it being an excellent electrical insulator which was used to shield telegraph cables. Incidentally it also insulates sound and heat, keeping the metamorphosing worm in comfy quiet until its environment gets unexpectedly hot and it is discarded for the products of its labor which are unraveled and turned into something unrecognizable.