Silk is a strong and luxurious fabric that has been used for high-end clothing and household items for centuries. Silk is collected from the cocoon of the silkworm, which winds about one mile of silk fibre into each cocoon. Each delicate silk fibre is tougher than a comparable amount of steel, making silk both luxurious and incredibly strong.
The silk fibre is produced by silkworms, which feast on mulberry leaves from the moment they are born until they are ready to spin their cocoons, which is about 35 days. The silkworm has two glands that produce a liquid form of silk which becomes a solid fibre when it comes into contact with air. When the silkworm is in the moth stage the silk fibre is collected, with each cocoon yielding about 1,000 yards of silk fibres. This fibre, known as raw silk, is then spun into silk yarn and threads. As of 2010, more silk was collected from silkworm farms than was collected from silkworms in the wild.
Due to the natural origin of the silk fibre, each thread varies in size and structure and no two threads are the same. It is a highly breathable fabric, appropriate for all climates. Silk collected from farmed silkworms is smooth, has a slight sheen, and is fairly uniform in colour. Silk from wild silkworms has more natural lumps in the filaments, making the woven silk vary much more in colour and texture. It has little to no sheen, but is stronger than silk collected from farmed silkworms. Both forms of silk absorb colours well, especially deep, rich colours. It is recommended that silk be dry cleaned.
The cost of silk varies widely, depending on the nature of the fibre, the method of collection, the country in which it was produced, the quality of the silk, and market conditions. As of October 2010, lower-quality dupioni silk can be found for as low as £5.10 a yard, with higher-end fabric costing up to hundreds of dollars per yard. Silk collected from wild silkworms is always more expensive than that collected from farmed silkworms, due to the extra work involved. Silk that is made from smaller silk filaments, yielding a finer weave, is also more expensive.