Silk is the filament secreted by the silkworm when spinning its cocoon, and the name for the threads, yarns and fabrics made from the filament. Most commercial silk is produced by the cultivated silkworm, Bombyx mori, which feeds exclusively on the leaves of certain varieties of mulberry trees and spins a thin, white filament.
The silkworm constructs its cocoon when it is preparing to enter its chrysalis stage. The cocoon is made from a double filament of silk, wrapped layer by layer around the insect's body and cemented by a gelatinous protein, sericin. If development is allowed to continue normally, in about 2 weeks the chrysalis will break through the cocoon filament and emerge as a moth.
Properties of Silk
Despite its delicate look and feel, silk is the strongest of all natural fibers. Woven into cloth, silk is lightweight but retain warmth, and it is valued as an insulating liner in gloves and footwear. Nevertheless, it is the coolest of hot weather fabrics, and it can absorb up to 30 percent of its weight in moisture without feeling wet. The fiber is remarkably resistant to it. Its low conductivity makes it excellent for electric wire insulation. Before nylon, silk was the only fiber strong and light enough to be used for parachutes, sheer hosiery, and surgical sutures. The strong of the silk never be created by human until now, this is a God creation that is very strong that can bear hundreds time of their weight itself, this is strongest than wire steel if compared between the weight and the strength.