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L’Histoire de Mode~Silk

Silk

Silk is a natural protein fibre, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity (sericulture). The shimmering appearance of silk is due to the triangular prism-like structure of the silk fibre, which allows silk cloth to refract incoming light at different angles, thus producing different colors.

Silks are produced by several other insects, but only the silk of moth caterpillars has been used for textile manufacturing. There has been some research into other silks, which differ at the molecular level. Silks are mainly produced by the larvae of insects undergoing complete metamorphosis, but also by some adult insects such as webspinners. 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 (spider silk).

Wild silk

A variety of wild silks, produced by caterpillars other than the

mulberry silkworm have been known and used in China, South Asia,

and Europe since ancient times. However, the scale of production

was always far smaller than that of cultivated silks. They differ

from the domesticated varieties in color and texture, and cocoons

gathered in the wild usually have been damaged by the emerging moth

before the cocoons are gathered, so the silk thread that makes up the cocoon

has been torn into shorter lengths. Commercially reared silkworm pupae are

killed by dipping them in boiling water before the adult moths emerge, or by

piercing them with a needle, allowing the whole cocoon to be unraveled as one

continuous thread. This permits a much stronger cloth to be woven from

the silk. Wild silks also tend to be more difficult to dye

than silk from the cultivated silkworm.

China

Silk fabric was first developed in ancient China, with some of the earliest examples

found as early as 3500 BC. Legend gives credit for developing silk to a Chinese empress,

Lei Zu (Hsi-Ling-Shih, Lei-Tzu). Silks were originally reserved for the Kings of China for their own use

and gifts to others, but spread gradually through Chinese culture and trade both geographically

and socially, and then to many regions of Asia. Silk rapidly became a popular luxury fabric in the

many areas accessible to Chinese merchants because of its texture and luster. Silk was in

great demand, and became a staple of pre-industrial international trade. In July 2007, archeologists

discovered intricately woven and dyed silk textiles in a tomb in Jiangxi province, dated to

the Eastern Zhou Dynasty roughly 2,500 years ago. Although historians have suspected a

long history of a formative textile industry in ancient China, this find of silk textiles

employing “complicated techniques” of weaving and dyeing provides direct

and concrete evidence for silks dating before the Mawangdui-discovery and other

silks dating to the Han Dynasty (202 BC-220 AD).

The first evidence of the silk trade is the finding of silk in the

hair of an Egyptian mummy of the 21st dynasty, c.1070 BC. Ultimately

the silk trade reached as far as the Indian subcontinent,

the Middle East, Europe, and North Africa. This trade

was so extensive that the major set of trade routes

between Europe and Asia has become known as

the Silk Road. The highest development

was in China.

The Emperors of China strove to keep knowledge of sericulture secret to maintain

the Chinese monopoly. Nonetheless sericulture reached Korea around 200 BC, about

the first half of the 1st century AD had reached ancient Khotan, and by AD 300

the practice had been established in India.

Thailand

Silk is produced, year round, in Thailand by two types of silkworms,

the cultured Bombycidae and wild Saturniidae. Most production

is after the rice harvest in the southern and northeast parts

of the country. Women traditionally weave silk on hand looms,

and pass the skill on to their daughters as weaving is considered

to be a sign of maturity and eligibility for marriage.

Thai silk textiles often use complicated patterns in various

colours and styles. Most regions of Thailand have their own

typical silks. A single thread filament is too thin to use on its

own so women combine many threads to produce a thicker,

usable fibre. They do this by hand-reeling the threads

onto a wooden spindle to produce a uniform strand of

raw silk. The process takes around 40 hours to

produce a half kilogram of Thai silk.

Many local operations use a reeling machine for this task, but some silk threads

are still hand-reeled. The difference is that hand-reeled threads produce three grades of silk: two

fine grades that are ideal for lightweight fabrics, and a thick

grade for heavier material. The silk fabric is soaked in extremely cold water and bleached

before dyeing to remove the natural yellow coloring of Thai silk yarn. To do this, skeins

of silk thread are immersed in large tubs of hydrogen peroxide. Once washed and dried,

the silk is woven on a traditional hand operated loom.[

India

Silk, known as “Paat” in Eastern India, Pattu in southern parts of India

and Resham in Hindi/Urdu, has a long history in India. Recent

archaeological discoveries in Harappa and Chanhu-daro suggest

that sericulture, employing wild silk threads from native silkworm

species, existed in South Asia during the time of the

Indus Valley Civilization, roughly contemporaneous

with the earliest known silk use in China. Silk is widely

produced today. India is the second largest producer of silk

after China. A majority of the silk in India is produced in Karnataka

State, particularly in Mysore and the North Bangalore regions of

Muddenahalli, Kanivenarayanapura, and Doddaballapur.

India is also the largest consumer of silk in the world. The

tradition of wearing silk sarees in marriages by the brides

is followed in southern parts of India. Silk is worn by people as a symbol

of royalty while attending functions and during festivals. Historically silk

was used by the upper classes, while cotton was used by the poorer classes.

Today silk is mainly produced in Bhoodhan Pochampally (also known as Silk City),

Kanchipuram, Dharmavaram, Mysore, etc. in South India and Banaras in the

North for manufacturing garments and sarees. “Murshidabad silk”, famous from

historical times, is mainly produced in Malda and Murshidabad district of West

Bengal and woven with hand looms in Birbhum

and Murshidabad district.

Another place famous for production of silk is Bhagalpur. The silk from Pochampally

is particularly well-known for its classic designs and enduring quality. The silk is

traditionally hand-woven and hand-dyed and usually also has silver threads woven into

the cloth. Most of this silk is used to make sarees. The sarees usually are very expensive and

vibrant in color. Garments made from silk form an integral part of Indian weddings and other

celebrations. In the northeastern state of Assam, three different types of silk are produced,

collectively called Assam silk: Muga, Eri and Pat silk. Muga, the golden silk, and Eri are

produced by silkworms that are native only to Assam. The heritage of silk rearing

and weaving is very old and continues today especially with the production of Muga and

Pat riha and mekhela chador, the three-piece silk sarees woven with traditional motifs.

Mysore Silk Sarees, which are known for their soft texture,

last many years if carefully maintained.

Ancient Mediterranean

In the Odyssey, 19.233, when Odysseus, while pretending to be someone

else, is questioned by Penelope about her husband’s clothing, he says

that he wore a shirt “gleaming like the skin of a dried onion” (varies with

translations, literal translation here) which could refer to the

lustrous quality of silk fabric. The Roman Empire knew of and traded

in silk. During the reign of emperor Tiberius, sumptuary laws were passed

that forbade men from wearing silk garments, but these proved ineffectual. Despite the

popularity of silk, the secret of silk-making only reached Europe around AD 550,

via the Byzantine Empire. Legend has it that monks working for the emperor

Justinian I smuggled silkworm eggs to Constantinople in hollow canes from

China. All top-quality looms and weavers were located inside the

Palace complex in Constantinople and the cloth produced was used

in imperial robes or in diplomacy, as gifts to foreign dignitaries.

The remainder was sold at very high prices.

Chemical properties

Silk emitted by the silkworm consists of two main proteins, sericin and fibroin, fibroin

being the structural center of the silk, and serecin being the sticky material surrounding it.

Fibroin is made up of the amino acids Gly-Ser-Gly-Ala-Gly-Ala and forms

beta pleated sheets. Hydrogen bonds form between chains, and side chains form above

and below the plane of the hydrogen bond network. The high proportion

(50%) of glycine, which is a small amino acid, allows tight packing and the

fibers are strong and resistant to breaking. The tensile strength is due to the many

interseeded hydrogen bonds, and when stretched the force is applied to these

numerous bonds and they do not break. Silk is resistant to most mineral acids, except

for sulfuric acid, which dissolves it.

It is yellowed by perspiration.

Uses

Silk’s absorbency makes it comfortable to wear in warm

weather and while active. Its low conductivity keeps

warm air close to the skin during cold weather. It is often

used for clothing such as shirts, ties, blouses, formal dresses,

high fashion clothes, lingerie, pyjamas, robes, dress suits,

sun dresses and kimonos. Silk’s attractive luster and drape

makes it suitable for many furnishing applications. It is

used for upholstery, wall coverings, window treatments

(if blended with another fiber), rugs, bedding and wall hangings.

While on the decline now, due to artificial fibers, silk has had many industrial

and commercial uses; parachutes, bicycle tires, comforter filling and artillery

gunpowder bags. A special manufacturing process removes the outer

irritant sericin coating of the silk, which makes it suitable as non-absorbable

surgical sutures. This process has also recently led to the

introduction of specialist silk underclothing for children and adults

with eczema where it can significantly

reduce itch.

Cultivation

Silk moths lay eggs on specially prepared paper. The eggs hatch and the caterpillars

(silkworms) are fed fresh mulberry leaves. After about 35 days and 4 moltings, the caterpillars

are 10,000 times heavier than when hatched and are ready to begin spinning a cocoon.

A straw frame is placed over the tray of caterpillars, and each caterpillar begins spinning a

cocoon by moving its head in a “figure 8” pattern. Two glands produce liquid silk and force

it through openings in the head called spinnerets. Liquid silk is coated in sericin, a water-soluble

protective gum, and solidifies on contact with the air. Within 2–3 days, the

caterpillar spins about 1 mile of filament and is completely encased in a cocoon.

The silk farmers then kill most caterpillars by heat, leaving some to

metamorphose into moths to breed the next generation of caterpillars.

Harvested cocoons are then soaked in boiling water to soften the sericin

holding the silk fibers together in a cocoon shape. The fibers are then

unwound to produce a continuous thread. Since a single thread is too fine and

fragile for commercial use, anywhere from three to ten

strands are spun together to form

a single thread of silk.

Animal rights

As the process of harvesting the silk from the cocoon kills the

larvae, sericulture has been criticized in the early 21st century by

animal rights activists, especially since artificial silks are available.

Mohandas Gandhi was also critical of silk production based on the Ahimsa

philosophy “not to hurt any living thing.” This led to Gandhi’s promotion

of cotton spinning machines, an example of which can be seen at

the Gandhi Institute. He also promoted Ahimsa silk, wild silk

made from the cocoons of wild and semi-wild silk moths.

Ahimsa silk is promoted in parts of Southern India for those

who prefer not to wear silk produced by

killing silkworms.

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