TRADITIONAL SILK MANUFACTURE:
Silk fibre is the fibres of silkworm cocoons. Only the healthiest silk moths are used for breeding. Their eggs are categorised, graded, and meticulously tested for infection. Unhealthy eggs are burned. The healthiest eggs may be placed in cold storage until they are ready to be hatched. Once the eggs are incubated, they usually hatch within seven days. They emerge at a mere one-eighth of an inch (3.2 mm) long and must be maintained in a carefully controlled environment.
Under normal conditions, the eggs would hatch once a year in the spring when mulberry trees begin to leaf (silkworms feed only on mulberry tree leaves, hence the seemingly out-of-place mention of mulberry trees!). But with the help of seri culturists, breeding can occur as many as three times per year.
The mulberry leaves are finely chopped and fed to the silkworms every few hours for 20 to 35 days. During this period the worms increase in size to about 3.5 inches (8.9 cm). They also shed their skin, or molt, approximately four times and change colour from gray to a translucent pinkish colour.
The Worms Into Cocoons:
When the silkworms starts to fidget and toss their heads back and forth, they are preparing to spin their cocoons. The caterpillar attaches itself to either a twig or rack for support. As the worm twists its head, it spins a double strand of fibre in a figure-eight pattern and constructs a symmetrical wall around itself. The filament is secreted from each of two glands called the spinneret located under the jaws of the silkworm. The insoluble protein-like fibre is called fibroin.
The Cocoon Fibre:
The fibroin is held together by sericin, a soluble gum secreted by the worm, which hardens as soon as it is exposed to air. The result is the raw silk fibre, called the bave. The caterpillar spins a cocoon encasing itself completely. It can then safely transform into the chrysalis, which is the pupa stage.
The Unethical Bit:
The natural course would be for the chrysalis to break through the protective cocoon and emerge as a moth. However, seri culturists must destroy the chrysalis so that it does not break the silk filament. This is done by stoving, or stifling, the chrysalis with heat.
This is heavily protested against by animal rights activists and vegans, who view the killing of these chrysali which would soon emerge as moths, immoral and cruel.
The Silk Processing Factory (Or "Filature"):
The filature is the factory in which the cocoons are processed into silk thread. In the filature the cocoons are sorted by various characteristics, including colour and size, so that the finished product can be of uniform quality. The cocoons must then be soaked in hot water to loosen the sericin. Although the silk is about 20% sericin, only 1% is removed at this stage. This way the gum actually facilitates the following stage in which the filaments are combined to form silk thread, or yarn.
Reeling Into Skeins:
Reeling may be achieved manually or automatically. The cocoon is brushed to locate the end of the fibre. It is threaded through a porcelain eyelet, and the fibre is reeled onto a wheel. Meanwhile, diligent operators check for flaws in the filaments as they are being reeled.
As each filament is nearly finished being reeled, a new fibre is twisted onto it, thereby forming one long, continuous thread. Sericin contributes to the adhesion of the fibres to each other.
The end product, the raw silk filaments, are reeled into skeins. These skeins are packaged into bundles weighing 5-10 pounds (2-4 kg), called books. The books are further packaged into bales of 133 pounds (60 kg) and transported to manufacturing centers.
Skeins Into Threads:
Silk thread, also called yarn, is formed by throwing, or twisting, the reeled silk. First the skeins of raw silk are categorised by colour, size, and quantity. Next they are soaked in warm water mixed with oil or soap to soften the sericin. The silk is then dried.
As the silk filaments are reeled onto bobbins, they are twisted in a particular manner to achieve a certain texture of yarn. For instance, "singles" consist of several filaments, which are twisted, together in one direction. The type of yarn created contributes to the type of fabric they will make: They are turned tightly for sheer fabrics and loosely for thicker fabrics. Combinations of singles and untwisted fibres may be twisted together in certain patterns to achieve desired textures of fabrics such as crepe de chine, voile, or tram. Fibres may also be manufactured in different patterns for use in the nap of fabrics, for the outside, or for the inside of the fabric.
The silk yarn is put through rollers to make the width more uniform. The yarn is inspected, weighed, and packaged. Finally, the yarn is shipped to fabric manufacturers
If you, like many others, find that this way of producing silk is too cruel, you might want to look at alternatives to silk, such as "Peace" or "Ahimsa" silk. The problems can be that most alternatives do not offer as much strength or smooth finishes, but they are certainly better than burning the imperfect eggs and killing the chrysali associated with usual silk production.
Take a look at our selection of Ahimsa Silks