Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from cocoons made by the larvae of the mulberry silkworm India, reared in captivity (sericulture). The shimmering appearance for which silk is prized comes from the fibers' triangular prism-like structure that allows silk cloth to refract incoming light at different angles. Silk's good absorbency, elegant, soft lustre and beautiful drape makes it comfortable to wear in warm weather and while active. Its low conductivity keeps warm air close to the skin during cold weather.
Only the silk of moth caterpillars has been used for textile manufacture. There has been research into other silks, which differ at the molecular level. Silks are mainly produced by the larvae of insects that complete metamorphosis, but also by some adult insects such as web spinners. Silk production is especially common in the Hymenoptera (bees, wasps, and ants), and is sometimes used in nest construction. Other types of arthropod produce silk, most notably various arachnids, such as spiders.
Silk fibers have a triangular cross section with rounded corners. This reflects light at many different angles, giving silk a natural shine. It has a smooth, soft texture that is not slippery, unlike many synthetic fibers. Its denier is 4.5 g/d when dry and 2.8-4.0 g/d when wet.
Silk has a good moisture regain of 11%. Its elasticity is moderate to poor: if elongated even a small amount it remains stretched. It can be weakened if exposed to too much sunlight. It may also be attacked by insects, especially if left dirty. Silk is a poor conductor of electricity and thus susceptible to static cling. Unwashed silk chiffon may shrink up to 8%, due to a relaxation of the fiber macrostructure. Silk is resistant to most mineral acids but will dissolve in sulfuric acid. It is yellowed by perspiration.
Silk may be considered a luxury, but caring for it properly doesn't is simple. Gentle washing, drying away from a heat source, and storage in material that provides air circulation is all silk needs to stay looking good. If you properly care for your silk garments, they'll keep their original softness and sheen for years.
Care instructions for most for silk items, especially for pure silk, recommend dry cleaning. While dry cleaning helps maintain the original texture of the fabric, it does carry some risks. Commonly used cleaning solutions aren't suited to silk, and silks can be damaged if placed in the same vat with rougher fabrics. To make sure your silk gets proper treatment, always tell the dry cleaner that your garment is made from silk, and make sure they know how to clean silk.
Silk fabric has been produced for over five thousand years, whereas the dry cleaning process has only been around since the 1840s. Clearly, dry cleaning isn't a must. Good quality silk, such as the Anne Wiggins London range, tends to looks better and last longer when hand washed, though. The natural coating on silk fibres reacts well to warm water, so hand washing also has the advantage of refreshing silk and giving it a better drape.
Silk can be hand washed in cool or lukewarm water using a mild detergent such as Woolite, Ivory soap, or a gentle shampoo dissolved in the water. Wool and silk-specific detergents will not coat the fibres, but generic detergents will. Because silk resists dirt and stains, only a small amount of soap should be used. Silk, like most natural fibres, doesn't tolerate abrupt changes in temperature very well, so stay with one water temperature throughout the wash.
Avoid soaking silk, as this may fade the dye or discolour it.
To not only revive faded or yellowed colours, but also protect the fabric from alkali damage, rinse the silk garment in water with a few tablespoons of white vinegar added. While some people prefer a matte finish, this texture is usually a sign of alkali damage, which can eventually make the fabric brittle. The vinegar rinse will minimize this. After the wash and vinegar rinse, rinse the silk garment thoroughly in cool water.
In general, machine washing is the worst way to clean silk, as the agitator and other garments can damage the fabric. However, if the instructions for your washing machine state that the machine is safe for silk, there should be no serious problem washing your silk garments in it. Before washing, make sure there's no soap or dirt on the inside of the machine that might stain the silk garment. Place the silk item in a mesh bag or a pillowcase loosely tied closed. Use a small amount of a very mild appropriate detergent and wash on a gentle cycle, such as a wool cycle, at a temperature of no more than 86°F / 30°C.
If you use a spin cycle, keep it as short as possible.
A capful of hydrogen peroxide and or a few drops of ammonia added to the wash will help keep your pale coloured silk bright, and rinsing silk in white vinegar diluted with water will help remove yellowing. While recent perspiration stains may be washed out or dabbed with a tablespoon of ammonia dissolved in half a cup of water, older perspiration may be removed with a vinegar solution. Unfortunately, though, perspiration stains on silk garment, as on many garments, may not be completely removable, as perspiration causes damage to the fibres.
Remember, whilst silk may be strong, harsh chemicals can cause permanent damage, so avoid using bleach or products that contain bleach, enzymes, or whiteners on your silk garment.
Even if you machine wash, never use a machine dryer to dry silk, as the friction and lack of humidity will likely damage the fabric. Instead, roll the silk item up in a bath towel and gently press the water out. Never wring silk. When most of the water is out, hang your garment up to dry. Keep the garment away from heat sources or direct sunlight, both of which can discolour silk.
Silk should be pressed while still damp, never when completely dry. If the item has dried, dampen it with water from a mineral water spritzer bottle before ironing. To avoid damage, turn the item inside out and iron on the reverse side of the fabric on a cotton-covered ironing board. Use a low setting and don't use steam, which can leave watermarks. Take care not to apply pressure to the seams of the garment.
For long-term storage, keep silk in a cotton pillowcase or other material that can breathe. Avoid plastic, which traps moisture and can cause yellowing and mildew. Silk, like other natural fibres, is a favourite with moths, so store cedar chips or balls with your silk to keep the bugs away.