Silk is a natural fiber derived from the cocoons of silkworms, which wrap themselves in a protein that forms a continuous thread up to 1 mile in length. Most commercially produced silk is obtained from the silkworms of the domesticated variety Bombyx Mori, which feed on the leaves of mulberry trees. To prevent the silkworms from breaking out of their cocoons naturally and so damaging the continuous silk fiber, the full length of the filament is preserved by killing the silkworm by steaming or piercing. Silk farming (sericulture) is highly labor-intensive and it requires large areas planted with mulberry trees because the yield per tree is very low (in the range of grams). The environmental impact of silk production varies according to farming practices: including the fertilizers and pesticides used for growing the trees (silkworms are very sensitive to agro-chemicals); the energy use in climate control for the chrysalises; the chemicals used to degum the silk filament; the water use for farming and fiber production; and the waste disposal methods. An alternative to commercially cultivated silk is silk obtained from wild silkworms who feed either on oak leaves or mulberry leaves and who have been left to emerge from their cocoons naturally, thus breaking the filament. However, the finest quality silk cannot be obtained from wild silkworms as the filament is much coarser than cultivated silk and is also of shorter length. One example of wild silk that is grown commercially is Tussah silk, produced by Tussah silkworms who break from their cocoons leaving a neat hole and longer filaments. Organic silk, produced without the use of fertilizers and pesticides for mulberry tree cultivation, is also available in small quantities. Silk is potentially compostable and biodegradable under suitable conditions, however, as with any other material, this depends on many other factors, such as processing chemicals and dyes used.(1-4)
SILK
