FASH 15 textiles silk

1. FASH 15 textiles silk

2. silk silk is a natural protein fiber produced by larvae of a moth like wool, composed of amino acids arranged in a polypeptide chain but it has no crosslinks silk culture began in China in 2640 B.C.—later spread to Korea & Japan, westward to India & Persia, then to Spain, France & Italy several attempts made in U.S.—none successful today, major producers are China, India, Japan

3. silk • universally accepted as a luxury fiber • combination of properties not possessed by any other fiber: • dry, tactile hand • unique natural luster • good moisture absorption • lively suppleness & draping qualities • high strength • most likely responsible for development of manufactured fiber industry

4. production of silk • sericulture is the production of cultivated silk • begins when silk moth lays eggs on specially prepared paper • when eggs hatch, caterpillars (larvae) are fed fresh, young mulberry leaves • after about 36 days & 4 moltings, silkworms are roughly 10,000 times heavier than when hatched—ready to begin spinning a cocoon (chrysalis case) • straw frame placed on a tray & silkworm spins cocoon by moving its head in a figure eight http://www.youtube.com/watch?v=hchVGxfc1ws&feature=related

5. production of silk silkworm produces silk in two glands and forces liquid silk through spinnerets—openings in its head in 2-3 days the silkworm will spin approximately 1 mile of filament and completely encase itself silkworm then metamorphoses into a moth—usually killed before reaching moth stage each cocoon yields approximately 1,000 yards of usable silk filament—raw silk http://www.youtube.com/watch?v=wbmEjTvszI&feature=related

6. production of silk several filaments combined to form a yarn operators must carefully join filaments so diameter of reeled silk remains uniform in size—uniformly reeled filament silk most valuable twist can be added—throwing—thrown yarn: single—simplest, 3-8 filaments twisted together staple silk—produced from cocoons in which filament broke or moth was allowed to mature— silk noils or silk waste

7. production of silk wild silk production is not controlled—silkworms feed on oak & cherry leaves; produce much less uniform fibers tussah silk most common type of wild silk—coarser, darker & cannot be bleached duppioni silk—wild silk; result of two silkworms spinning cocoons together—irregular in diameter, thick-and-thin appearance momme—describes the weight of the silk; one momme weighs 3.75 grams—higher numbers describe heavier fabrics

8. physical structure of silk silk is only natural filament fiber solid fiber, smooth but irregular in diameter along its shaft filaments are triangular in cross section, with rounded corners fibers are very fine— 1.25 denier/filament (dpf) wild silks slightly coarser with slight striations along length

9. chemical composition of silk protein in silk is fibroin—15 amino acids in polypeptide chains has no cross linkages and no bulky side chains molecular chains are not coiled, as in wool, but are pleated and packed closely together high orientation contributes to its strength elasticity due to some amorphous areas between crystalline areas

10. properties of silk—aesthetics silk can be dyed and printed in brilliant colors—available in many fabric types for interior & apparel uses luster is soft with an occasional sparkle due to smooth but slightly irregular surface & triangular cross section fabric has smooth appearance & luxurious hand—not as slippery as many synthetic fibers wild silks have duller luster & more pronounced texture http://www.youtube.com/watch?v=FajTk_GeAXM&feature=related

11. properties of silk—aesthetics in filament form, has poor covering power—historically often treated with metallic salts weighting to produce better drape, covering power, & dye absorption weighted silks aged poorly—shattered silk

12. properties of silk—durability silk has moderate abrasion resistance—seldom receives harsh abrasion due to luxury of use one of strongest natural fibers dry—may lose up to 20% of its strength when wet not as elastic as wool because of lack of cross linkages—when silk is stretched even a small amount it does not return to its original length

13. properties of silk—comfort & appearance silk has good absorbency—sheer silks comfortable in summer poor conductor of heat (like wool)—heavier silks comfortably warm in winter may develop static cling due to smoothness of yarns and fabric weight silk is smooth and soft an not irritating to skin silk has moderate resistance to wrinkling & fibers do not shrink

14. properties of silk—care • dry cleaning solvents do not damage silk—may be recommended for silk items because of: • yarn types • dyes with poor fastness to water or laundering • product or fabric construction methods • washable silk items can be laundered in mild detergent solution with gentle agitation • care should be taken with wet silk—avoid stress • should be pressed after laundering

15. properties of silk—care silk may water spot easily—before laundering, test in obscure place can be damaged by strong soaps or detergents & high temperatures chlorine bleaches should be avoided—hydrogen peroxide & sodium perborate are safe if direction carefully followed silk is weakened and yellowed by exposure to sunlight and perspiration may be attacked by insects, especially carpet beetles

16. environmental concerns & sustainability • mulberry tree— • grown in regions where soil may be too poor to grow other crops • help retain soil & contribute to income of small farms • deciduous so silk production is limited to one generation each year • silkworm— • susceptible to disease & changes in temp • raised for silk they produce—most killed before maturation • some cruelty free silk available or wild silk

17. environmental concerns & sustainability silk production is labor intensive—produced where labor costs are low, may use child labor however in many areas this allows families to work together—each family contributing to better economic situation for family in Mexico silk production provides economic freedom for women mechanization could have harmful economic impact on regions that depend upon hand labor for income

18. environmental concerns & sustainability silk production makes extensive use of water and chemicals to clean fiber & remove sericin—waste water usually discharged into ground water with no treatment use of dyes is high—dyeing requires heat, water, dyes & other chemicals environmental regulations are minimal in many parts of the world where silk is produced

19. uses of silk • silk often imitated, cannot be duplicated exactly • drape, luster, texture, appearance, comfort, and strength contribute to continued popularity • extremely versatile • sheer, gossamer chiffons to heavy, brocades & velvets • active summer sportswear to silk underwear, socks & leggings • designer garments to discount store shirts • upholstery, wall coverings, wall hangings & drapery • handmade rugs • sleeping bag liners, blankets & bedsheets • medical uses—sutures, prosthetic arteries, scaffolds & grafts (regenerate ligaments, tendons & other connective tissue)

20. spider silk • produced by some spiders—researchers fascinated due to exceptional strength, elasticity, & light weight • capture silk—highly elastic & hydroscopic • dragline silk—very strong for fine size • spider farms not possible—spiders territorial & kill one another before much silk is produced • modified, transgenic silkworm? • possible uses— • civil engineering & road construction • protective clothing • bone or tendon repair

21. identification of natural protein fibers • natural protein fibers can be identified with microscope fairly easily • correct ID of specialty wools important due to fraudulent blends • silk surface not as regular as that of most manufactured fibers • soluble in sodium hypochlorite • in burn test, fibers smell like burning hair