The process of producing silk starts when the butterfly lays 300 to 600 eggs in the course of seven days. Worms have to eat large quantities of mulberry to become adults in about 32 days.
The spinning of silk consists on winding the thread of the cocoon as it's done with as skein of would. Cocoons are immersed in water at 90 °, then brush the outside to find out the string and in a bowl of water at 40/50º ropes together eight cocoons.
The normal length of thread is 600 to 1,200 meters, but in some cases can reach 4000 meters.
Silk is a natural conitnuous filament (the only fiber that Nature provides yarn) is a solid fiber withj a regular diameter.
Because is such an expensive fiber, the use of the material is maximized; once the filament yarn, waste (empty cocoons, remains of winding filament, ...) are treated to be reyarn, and the last remains, unusable for spinning, are used for making batts and other fillings.