Silk is a fine, tough, elastic fiber produced by caterpillars, commonly called silkworms. Silk is one of the oldest known textile fibers. Chinese tradition credits Lady Hsi-Ling-Shih, wife of the Emperor Huang Ti, with the discovery of the silkworm and the invention of the first silk reel. Dating to around 3000 BC, a group of ribbons, threads, and woven fragments was found in China. Also found, along the lower Yangzi River, were 7,000 year-old spinning tools, silk thread, and fabric fragments.
Silk filament was first woven into cloth in Ancient China. The Chinese successfully guarded this secret until 300AD, when Japan, and later India, learned the secret. In 550 AD, two Nestorian monks were sent to China to steal mulberry seeds and silkworm eggs, which they hid in their walking staffs, and then brought them back to Rome. By the 17th century, France was the silk center of the West. Unfortunately, the silkworm did not flourish in the English climate, nor has it ever flourished in the U.S.
Sericulture is the term for the raising of silkworms. The blind, flightless moth, Bombyx mori, lays more than 500 tiny eggs. After hatching, the tiny worms eat chopped mulberry leaves continuously until they are ready to spin their cocoons. After gathering the complete cocoons, the first step in silk manufacturing is to kill the insects inside the cocoons with heat. The cocoons are then placed in boiling water to loosen the gummy substance, sericin, holding the filament together. The filament is unwound, and then rewound in a process called reeling. Each cocoon's silk filament is between 600 and 900 meters long. Four different types of silk thread may be produced: organzine, crepe, tram, and thrown singles. During the last 30 years, in spite of the use of man-made fibers, world silk production has doubled.
Raw silk is traded on the Kansai Agricultural Commodities Exchange (KANEX) in Japan. Dried cocoons are traded on the Chuba Commodity Exchange (CCE). Raw silk and dried cocoons are traded on the Yokohama Commodity Exchange.
Supply - World production of silk in 2002, the latest reporting year, rose +0.8% to 132,000 metric tons, which was a record high and sharply above the 12-year low of 85,000 posted in 1997. China is the world's largest producer of silk by far with 71% of world production in 2002. Other key producers include India with 11% of world production, Vietnam (9%), and Turkmenistan (3%).
Trade - In 2003, the latest reporting year, the world's largest exporters of silk were China with 62% of world exports, Japan with 2.4%, and Brazil with 1.5%.
In 2003,the world's largest importers of silk were India (with 33% of world imports), Italy (13%), Japan (10%), and South Korea (6%).