Natural silk is spun as a thread by silk-worms. They use it to form a cocoon. Unlike other natural threads, the silk-worm’s thread is very long — up to one kilometre (0.62 miles). Traditionally made in Asia, silk was such a sought-after textile that the route from Europe to the East became known as the Great Silk Road.
Silk is made from Silkworms (known as Bombyx mori) and Bombyx mori eats mulberry leaves. The silkworm is the larva or caterpillar of the domestic silk moth, Bombyx mori’. Fine silk and Bombyx mori is interconnected worm or moth.
When mulberry leaves put forth their leaves – this is the time that these silkworms are born- these helpless worms feed on the leaves. In the silk manufacturing process, they are kept in a tray filled with carefully selected tender and succulent mulberry leaves for about 25-28 days. It is said that a worm eats about 10,000 times its body weight of mulberry leaves and increase their weight to almost 5000 times in this short span.
Sericulture refers to Rearing of silkworm for the production of silk. When it is fully grown, it climbs onto a twig in the natural environment. In sericulture, it is placed on a special frame. If you are growing it at home you will have to give it a bamboo/plastic/metal frame, for the larvae to weave his cocoon around it.
The worm starts to spins a cocoon around itself. This cocoon is made with a sticky substance that comes out of an opening in its underlip. This is made by mixing a fibroin protein compounds that come out of its salivary glands and another substance called sericin (silk gum) in its mouth.
As it comes out, this sticky substance solidifies when in contact with air into the silk fiber. In three days it makes thousands of meters of this fiber. For about 10-15 days the silkworm will be a pupa inside this self-made home. Then it undergoes metamorphosis into a furry winged moth.
The moth will eventually worm itself out of the cocoon – but this is not allowed to happen unless the moth is required to breed eggs. This will damage the silk fibers in the cocoon or cut it short, so these worms are killed by putting them in boiling water /oven. When the worms are put in boiling water the sticky sericin coating of the silkworm also dissolves.
Sometimes two silkworms will nest together forming a single cocoon producing fibers that are thick and thin – the fabric made from these fibers are called Dupioni silk Cocoons are sorted according to their color and texture. The single cocoon in carefully unraveled and the fiber is wound /reeled on a spool. Usually, about 6 filaments are reeled together to create a thread. The single strands of the thread may be doubled and twisted for strength.
This long thin fiber is silk with many impurities. The fibers are taken out and washed thoroughly to remove any residue/gum etc. The yarns are boiled in a soap solution to remove the natural silk gum or sericin. It has to undergo many washes and treatments before it is usable for weaving. Thus you get your silk filaments ready to be weaved into fabric.
Picture Credit : Google