Silk

Silk is a natural fiber that is made by silk worms. It is made of the protein molecules fibroin which contains approximately 15 different amino acids and is usually forms a beta sheet structure. Since silk is a natural fiber, it has a tendency to rot. It is the only natural fiber cut into filament lengths.

Silk is most often used as material toward very elegant, high class wardrobe, lining on equestrian helmets, and are very well known for there presence in japanese kimonos. It is a very valuable material due to its strength, smooth texture and due to the fact that it is completely natural, coming from the silk worm. The silk worm is actually a caterpillar of a moth which uses silk strands to create a cocoon. The silk worm is not killed in the process of silk production.
 * __Uses for silk__**

Silk, from a silk worm in Asia, has many different forms based on production. The triangular shape of the fiber cross section is what gives it the lustrous look that it contains and and the smoothness that it has when you touch it. It can be found in China, India, Thailand, Middle East, Mediterranean, Europe, and North America. The glycine that silk contains makes it strong due to the fact that it is packed tightly due to its cross sectional shape which is triangular. Silk forms beta sheets in its molecular structure which is shown below in both the 3D picture and the flat model. Silk pillowcases are also amazing at keeping your hair in check. Silk is woven closer together than cotton and other materials. This makes silk much gentler on your hair. Silk allows your hair to glide over the pillow without getting caught in the fibers. I immediately noticed a huge difference the next morning. I have long thick hair and it looked nearly as good the next morning, saving me time I would have spend restyling.
 * Characteristics of Silk**
 * high breaking tenacity
 * high durability
 * high comfort
 * lustrous and aesthetically pleasing
 * high absorbency
 * sensitive and poor resistance to strong acids, alkalis, and light

The production of silk is rather extensive. The term for the production is called "sericulutre" and involves extruding filaments from silkworms, which are larvae of the domestic silkmoth "bombyx mori." Silk filaments are extracted in pairs that are cemented together with "sericin," or silk gum. From here, depending on what type of silk it is, the process for finishing and selling the fiber is different. **Raw silk** has not been degummed and therefore is a gray, tan, or yellow color. **Degummed silk** has had the sericin removed with warm water and mild soap. The color is white and the weight has been lowered. Normally, degummed silk is soaked in tin salts to regain some weight to make it more appropriate for draping for clothing. **Spun silk** has been cut into a staple length rather than the natural filament length. **Wild silk** is silk produced from a different type of silk worm. Tussah is the most common type of wild silk and differs from normal silk in color and texture.

In regions where silk is produced, regulations on disposal of chemicals and water are sometimes poor. Silk requires large amounts of dye (if color change is desired) and water to degum and alter the appearance. Also, the silk worms usually die after being used for their silk filaments and many are raised specifically for silk production.
 * Environmental/Silkworm Concerns**

Facts About Silk Fabric

Silk is most commonly made out of spiders' silk which is tested and has more strength than most metal products. Kevlar is a main by-product of spider silk and it is the protective coating in bullet proof vests. It can stop a bullet that is shot from 12 feet away. Large amounts of research has been done on how to use spider silk in place of metal products for the fact that it is not comparable to anything else in its strength and tenacity. Mass producing spider silk would be extremely expensive and inefficient, nearly impossible.
 * Chinese history credits the invention of silk fabric to Yuen Fei, the concubine of an Emperor who ruled in 2,600 B.C. Legend has it she dropped a cocoon into hot tea and it unraveled. She, by reason of the discovery, has been deified and is worshipped as the goddess of silk worms.
 * Tusah silk is produced by silkworms that feed on oak leaves.
 * Silk dupioni is produced from 2 silkworms that spin a cocoon together, thus making a strong double-thread silk. Dupioni silk is currently enjoying great popularity.
 * The finest quality silk is made by mulberry silk moth, Bombyx mori, which, of course, feeds on mulberry leaves.
 * The average cocoon contains 300-400 meters of silk.
 * It takes about 5500 silkworms to produce 1 kg (2.2lb) of raw silk!
 * One ounce of eggs produces about 20,000 worms, which consume a ton of mulberry leaves during their lifetime.
 * Silk has been unearthed in the Qianshanyang Village of Huzhou in Zhejiang (China) and has been estimated to have been produced 4700 years ago!
 * The term SHANTUNG (A heavy wild-silk fabric with a rough surface) comes from the region of Shantung in China. The term ORGANDY (crisp cotton or silk fabric) comes from the town named Urgench (in present-day Uzbekistan in Central Asia). It was on the old silk route and was an early market for Chinese silk fabric.
 * Countries all over the world celebrate silk by issuing stamps in honor of sericulture (silk production).

Several different spider species can produce incredibly strong silk for their webs, but because these organims are so incredibly small scientists have no way of substituting spider silk for metal by-products. Spider silk in normal apparel is incredibly cost prohibitive, but is comfortable and has very high luster. Spiders also produce different forms and strengths of their silk depending on the end use of it, for example for a protective nest for babies one of the thickest silks will be produced by the spider.