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Silk is a
natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and ...
protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a No ...

protein
fiber Fiber or fibre (from la, fibra, links=no) is a natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including ...

fiber
, some forms of which can be
woven Woven fabric is any textile A textile is a flexible material made by creating an interlocking bundle of yarn Yarn is a long continuous length of interlocked fibres, suitable for use in the production of textiles, sewing, crocheting, knit ...

woven
into
textile A textile is a flexible material made by creating an interlocking bundle of yarn Yarn is a long continuous length of interlocked fibres, suitable for use in the production of textiles, sewing, crocheting, knitting, weaving, embroidery, ...

textile
s. The protein fiber of silk is composed mainly of
fibroin Fibroin is an insoluble protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one location to another. Prote ...
and is produced by certain insect
larva A larva (plural larvae ) is a distinct juvenile form many animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that f ...
e to form cocoons. The best-known silk is obtained from the cocoons of the larvae of the
mulberry silkworm ''Bombyx mori'', the domestic silk moth, is an insect from the moth Moths are a paraphyletic group of insects that includes all members of the Order (biology), order Lepidoptera that are not Butterfly, butterflies, with moths making up the ...
''
Bombyx mori ''Bombyx mori'', the domestic silk moth, is an insect from the moth Moths are a paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and all descendants of that ancestor excluding a ...

Bombyx mori
'' reared in captivity (
sericulture Sericulture, or silk farming, is the cultivation of silkworm ''Bombyx mori'', the domestic silk moth, is an insect from the moth Moths are a paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last ...

sericulture
). The shimmering appearance of silk is due to the triangular
prism A prism An optical prism is a transparent optics, optical element with flat, polished surfaces that refraction, refract light. At least one surface must be angled—elements with two parallel surfaces are not prisms. The traditional geometrical ...

prism
-like structure of the silk fibre, which allows silk cloth to refract incoming light at different
angle In Euclidean geometry Euclidean geometry is a mathematical system attributed to Alexandrian Greek mathematics , Greek mathematician Euclid, which he described in his textbook on geometry: the ''Euclid's Elements, Elements''. Euclid's method c ...

angle
s, thus producing different colors. Silk is produced by several insects; but, generally, only the silk of moth caterpillars has been used for textile manufacturing. There has been some research into other types of silk, which differ at the molecular level. Silk is mainly produced by the larvae of insects undergoing
complete metamorphosis Holometabolism, also called complete metamorphosis (biology), metamorphosis, is a form of insect development which includes four life stages: egg (biology), egg, larva, pupa and imago or adult. Holometabolism is a synapomorphy, synapomorphic trait ...
, but some insects, such as
webspinner The order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or waste, and the habit ...
s and raspy crickets, produce silk throughout their lives. Silk production also occurs in
hymenoptera Hymenoptera is a large order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or wa ...

hymenoptera
(
bee Bees are flying insects closely related to wasps and ants, known for their role in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

bee
s,
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The ...

wasp
s, and
ant Ants are eusocial Eusociality (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population i ...

ant
s),
silverfish The silverfish (''Lepisma saccharinum'') is a species of small, primitive, wingless in the (formerly ). Its derives from the insect's silvery light grey colour, combined with the fish-like appearance of its movements. The (''L. saccharinum'' ...

silverfish
,
mayflies Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern U.S.; also up-winged flies in the United Kingdom) are aquatic insects belonging to the order (biology), order Ephemeroptera. This order is part of an ancient gro ...

mayflies
,
thrips Thrips (Order (biology), order Thysanoptera) are minute (mostly 1 mm long or less), slender insects with fringed wings and unique asymmetrical mouthparts. Different thrips species feed mostly on plants by puncturing and sucking up the con ...

thrips
,
leafhopper A leafhopper is the common name for any species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the la ...

leafhopper
s,
beetle Beetles are a group of insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known a ...

beetle
s,
lacewing The insect Insects or Insecta (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Thr ...

lacewing
s,
flea Flea, the common name for the order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, tr ...
s,
flies Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

flies
, and
midge A midge is any small fly, including species in several family (biology), families of non-mosquito Nematoceran Diptera. Midges are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zo ...

midge
s. Other types of
arthropod An arthropod (, (gen. ποδός)) is an invertebrate animal having an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda,Reference showing that Euarthropoda is a phylum: ...
s produce silk, most notably various
arachnid Arachnida () is a class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytica ...

arachnid
s, such as
spider Spiders (order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or waste, and the ...

spider
s.


Etymology

The word silk comes from ang, sioloc, from grc, σηρικός, translit=sērikós, "silken", ultimately from the Chinese word "sī" and other Asian sources—compare
Mandarin Mandarin may refer to: * Mandarin (bureaucrat), a bureaucrat of Imperial China (the original meaning of the word) ** by extension, any senior government bureaucrat A bureaucrat is a member of a bureaucracy and can compose the administration o ...
"silk", Manchurian ,
Mongolian Mongolian may refer to: * Something of, from, or related to Mongolia, a country in Asia * Mongolian people, or Mongols * Mongolia (1911–24), the government of Mongolia, 1911–1919 and 1921–1924 * Mongolian language * Mongolian alphabet * Mongo ...

Mongolian
.


History

The production of silk originated in
China China (), officially the People's Republic of China (PRC; ), is a country in East Asia East Asia is the eastern region of Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere ...

China
in the
Neolithic The Neolithic period is the final division of the Stone Age The Stone Age was a broad prehistoric Prehistory, also known as pre-literary history, is the period of human history Human history, also known as world history, is t ...
period, although it would eventually reach other places of the world ( culture, 4th millennium BC). Silk production remained confined to China until the
Silk Road The Silk Road () was and is a network of trade routes connecting the Eastern world, East and Western culture, West, from the 2nd century BCE to the 18th century CE. It was central to the economic, cultural, political, and religious interactions ...

Silk Road
opened at some point during the latter part of the 1st millennium BC, though China maintained its virtual
monopoly A monopoly (from Greek el, μόνος, mónos, single, alone, label=none and el, πωλεῖν, pōleîn, to sell, label=none) is as described by Irving Fisher, a market with the "absence of competition", creating a situation where a specific ...

monopoly
over
silk production File:Silkworm & cocoon.jpg, 200px, Silkworm and cocoon Sericulture, or silk farming, is the cultivation of silkworms to produce silk. Although there are several commercial species of silkworms, ''Bombyx mori'' (the caterpillar of the domestic sil ...

silk production
for another thousand years.


Wild silk

Several kinds of wild silk, produced by
caterpillar Caterpillars ( ) are the larva, larval stage of members of the order Lepidoptera (the insect order comprising butterfly, butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawfly ...

caterpillar
s other than the
mulberry ''Morus'', a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In ...

mulberry
silkworm, have been known and spun in
China China (), officially the People's Republic of China (PRC; ), is a country in East Asia East Asia is the eastern region of Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere ...

China
,
South Asia South Asia is the southern region of Asia Asia () is 's largest and most populous , located primarily in the and . It shares the continental of with the continent of and the continental landmass of with both Europe and . Asia cov ...

South Asia
, and
Europe Europe is a continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of scienc ...

Europe
since ancient times, e.g. the production of Eri silk in
Assam, India Assam (, ) is a state in northeastern India India (Hindi: ), officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by population, second-most populous country, the List of ...

Assam, India
. However, the scale of production was always far smaller than for cultivated silks. There are several reasons for this: first, they differ from the domesticated varieties in colour and
texture Texture may refer to: Science and technology * Surface texture, the texture means smoothness, roughness, or bumpiness of the surface of an object * Texture (roads), road surface characteristics with waves shorter than road roughness * Texture (co ...
and are therefore less uniform; second, cocoons gathered in the wild have usually had the pupa emerge from them before being discovered so the silk thread that makes up the cocoon has been torn into shorter lengths; and third, many wild cocoons are covered in a mineral layer that prevents attempts to reel from them long strands of silk. Thus, the only way to obtain silk suitable for spinning into textiles in areas where commercial silks are not cultivated was by tedious and labor-intensive
carding Carding is a mechanical process that disentangles, cleans and intermixes fibres to produce a continuous web or sliver (textiles), sliver suitable for subsequent processing. This is achieved by passing the fibres between differentially moving surf ...
. Some natural silk structures have been used without being unwound or spun. Spider webs were used as a wound dressing in ancient Greece and Rome, and as a base for
painting Painting is the practice of applying paint Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, ...
from the 16th century. Caterpillar nests were pasted together to make a fabric in the
Aztec Empire The Aztec Empire, or the Triple Alliance ( nci, Ēxcān Tlahtōlōyān, Help:IPA for Nahuatl, jéːʃkaːn̥ t͡ɬaʔtoːˈlóːjaːn̥, was an alliance of three Nahua peoples, Nahua city-states: , , and . These three city-states ruled th ...

Aztec Empire
. Commercial silks originate from reared silkworm pupae, which are bred to produce a white-colored silk thread with no mineral on the surface. The pupae are killed by either dipping them in boiling water before the adult moths emerge or by piercing them with a needle. These factors all contribute to the ability of the whole cocoon to be unravelled as one continuous thread, permitting 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. A technique known as demineralizing allows the mineral layer around the cocoon of wild silk moths to be removed, leaving only variability in color as a barrier to creating a commercial silk industry based on wild silks in the parts of the world where wild silk moths thrive, such as in Africa and South America.


China

Silk use in fabric was first developed in ancient China. The earliest evidence for silk is the presence of the silk protein
fibroin Fibroin is an insoluble protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one location to another. Prote ...
in soil samples from two tombs at the
neolithic The Neolithic period is the final division of the Stone Age The Stone Age was a broad prehistoric Prehistory, also known as pre-literary history, is the period of human history Human history, also known as world history, is t ...
site
Jiahu Jiahu () was the site of a Neolithic settlement based in the central plain of ancient China, near the Yellow River. It is located between the floodplains of the Ni River (China), Ni River to the north, and the Sha River to the south, north of ...

Jiahu
in
Henan Henan (; ; alternatively Honan) is a landlocked province of China The provincial level administrative divisions () are the highest-level administrative divisions of China. There are 34 such divisions claimed by the People's Republic of ...

Henan
, which date back about 8,500 years. The earliest surviving example of silk fabric dates from about 3630 BC, and was used as the wrapping for the body of a child at a
Yangshao culture The Yangshao culture was a Neolithic The Neolithic period is the final division of the Stone Age, with a wide-ranging set of developments that appear to have arisen independently in several parts of the world. It is first seen about 12,000 ye ...
site in Qingtaicun near
Xingyang Xingyang (), is a county-level city of Henan, Henan Province, South Central China, South Central China, it is under the administration of the prefecture-level city of Zhengzhou. It is situated 15 kilometers to the west of Zhengzhou city proper. Th ...
, Henan. Legend gives credit for developing silk to a Chinese empress,
Leizu Leizu (), also known as Xi Ling-shi (, Wade–Giles Hsi Ling-shih), was a legendary Chinese Chinese can refer to: * Something related to China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the Li ...

Leizu
(Hsi-Ling-Shih, Lei-Tzu). Silks were originally reserved for the Emperors of China for their own use and gifts to others, but spread gradually through
Chinese culture Chinese culture () is one of the world's oldest cultures, originating thousands of years ago. The culture prevails across a large geographical region in East Asia and is extremely diverse and varying, with customs and traditions varying grea ...
and trade both geographically and socially, and then to many regions of
Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere, Eastern and Northern Hemisphere, Northern Hemisphere of the Earth, Hemispheres. It shares the continental landmass of Eurasia with the cont ...

Asia
. Because of its texture and lustre, silk rapidly became a popular luxury fabric in the many areas accessible to Chinese merchants. Silk was in great demand, and became a staple of pre-
industrial Industrial may also refer to: Industry * Industrial archaeology, the study of the history of the industry * Industrial engineering, engineering dealing with the optimization of complex industrial processes or systems * Industrial loan company, a f ...
international
trade Trade involves the transfer of goods from one person or entity to another, often in exchange for money. Economists refer to a system A system is a group of Interaction, interacting or interrelated elements that act according to a set of r ...

trade
. Silk was also used as a surface for writing, especially during the Warring States period (475-221 BCE). The fabric was light, it survived the damp climate of the Yangtze region, absorbed ink well, and provided a white background for the text. In July 2007, archaeologists discovered intricately woven and dyed silk
textile A textile is a flexible material made by creating an interlocking bundle of yarn Yarn is a long continuous length of interlocked fibres, suitable for use in the production of textiles, sewing, crocheting, knitting, weaving, embroidery, ...

textile
s in a tomb in
Jiangxi Jiangxi (; ; alternately romanized as Kiangsi or Chianghsi, Gan Chinese Gan, Gann or Kan is a group of Sinitic languages spoken first language, natively by many people in the Jiangxi province of China, as well as significant populations in ...

Jiangxi
province, dated to the Eastern
Zhou dynasty The Zhou dynasty ( ; Old Chinese Old Chinese, also called Archaic Chinese in older works, is the oldest attested stage of Chinese Chinese can refer to: * Something related to China China, officially the People's Republic of China ( ...
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 evidence for silks dating before the
Mawangdui Mawangdui () is an archaeological site An archaeological site is a place (or group of physical sites) in which evidence of past activity is preserved (either prehistoric Prehistory, also known as pre-literary history, is the period of hu ...
-discovery and other silks dating to the
Han dynasty#REDIRECT Han dynasty The Han dynasty () was the second Dynasties in Chinese history, imperial dynasty of China (202 BC – 220 AD), established by the rebel leader Liu Bang and ruled by the House of Liu. Preceded by the short-lived Qin dynas ...

Han dynasty
(202 BC – 220 AD). Silk is described in a chapter of the '' Fan Shengzhi shu'' from the Western Han (202 BC – 9 AD). There is a surviving calendar for silk production in an Eastern Han (25–220 AD) document. The two other known works on silk from the Han period are lost. The first evidence of the long distance silk trade is the finding of silk in the hair of an
Egypt Egypt ( ar, مِصر, Miṣr), officially the Arab Republic of Egypt, is a transcontinental country This is a list of countries located on more than one continent A continent is one of several large landmasses. Generally identi ...

Egypt
ian
mummy A mummy is a dead human Humans (''Homo sapiens'') are the most abundant and widespread species In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, B ...

mummy
of the 21st dynasty, c.1070 BC. The silk trade reached as far as the Indian subcontinent, the
Middle East The Middle East ( ar, الشرق الأوسط, ISO 233 The international standard An international standard is a technical standard A technical standard is an established norm (social), norm or requirement for a repeatable technical task whi ...

Middle East
,
Europe Europe is a continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of scienc ...

Europe
, and
North Africa North Africa or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in th ...

North Africa
. This trade was so extensive that the major set of trade routes between Europe and Asia came to be known as the
Silk Road The Silk Road () was and is a network of trade routes connecting the Eastern world, East and Western culture, West, from the 2nd century BCE to the 18th century CE. It was central to the economic, cultural, political, and religious interactions ...

Silk Road
. The
Emperors of China Emperor of China, or ''Huángdì'' (), was the monarch A monarch is a head of stateWebster's II New College DictionarMonarch Houghton Mifflin. Boston. 2001. p. 707. Life tenure, for life or until abdication, and therefore the head of state of ...
strove to keep knowledge of
sericulture Sericulture, or silk farming, is the cultivation of silkworm ''Bombyx mori'', the domestic silk moth, is an insect from the moth Moths are a paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last ...

sericulture
secret to maintain the Chinese
monopoly A monopoly (from Greek el, μόνος, mónos, single, alone, label=none and el, πωλεῖν, pōleîn, to sell, label=none) is as described by Irving Fisher, a market with the "absence of competition", creating a situation where a specific ...

monopoly
. Nonetheless, sericulture reached
Korea Korea is a region In geography, regions are areas that are broadly divided by physical characteristics (physical geography), human impact characteristics (human geography), and the interaction of humanity and the environment (environmental ...

Korea
with technological aid from China around 200 BC, the ancient
Kingdom of Khotan The Kingdom of Khotan was an ancient Iranian peoples, Iranian Saka Buddhism, Buddhist kingdom located on the branch of the Silk Road that ran along the southern edge of the Taklamakan Desert in the Tarim Basin (modern Xinjiang, China). The ancien ...

Kingdom of Khotan
by AD 50, and India by AD 140. In the ancient era, silk from China was the most lucrative and sought-after luxury item traded across the Eurasian continent, and many civilizations, such as the ancient Persians, benefited economically from trade. File:Women placing silkworms on trays together with mulberry leaves (Sericulture by Liang Kai, 1200s).jpg , The silkworms and mulberry leaves are placed on trays. File:Men preparing twig frames where silkworms will spin cocoons (Sericulture by Liang Kai, 1200s).jpg, Twig frames for the silkworms are prepared. File:Weighing and sorting the cocoons (Sericulture by Liang Kai, 1200s).jpg, The cocoons are weighed. File:Soaking the cocoons and reeling the silk (Sericulture by Liang Kai, 1200s).jpg, The cocoons are soaked and the silk is wound on spools. File:Weaving the silk (Sericulture by Liang Kai, 1200s).jpg, The silk is woven using a loom.


Northeastern India

In the northeastern state of
Assam Assam (, ) is a state in Northeast India, northeastern India, south of the eastern Himalayas along the Brahmaputra Valley, Brahmaputra and Barak River valleys. Assam covers an area of . The state is bordered by Bhutan and Arunachal Pradesh to ...

Assam
, three different types of indigenous variety 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. They have been reared since ancient times similar to other East and South-East Asian countries.


India

Silk has a long history in India. It is known as ''Resham'' in eastern and north India, and ''Pattu'' in southern parts of
India India, officially the Republic of India (Hindi Hindi (Devanagari: , हिंदी, ISO 15919, ISO: ), or more precisely Modern Standard Hindi (Devanagari: , ISO 15919, ISO: ), is an Indo-Aryan language spoken chiefly in Hindi Belt, ...

India
. Recent archaeological discoveries in
Harappa Harappa (; Urdu Urdu (; ur, , ALA-LC: ) is an Indo-Aryan language spoken chiefly in South Asia South Asia is the southern region of Asia, which is defined in both geography, geographical and culture, ethno-cultural terms. The regi ...

Harappa
and
Chanhu-daro Chanhu-daro is an archaeological site belonging to the Indus Valley Civilization. The site is located south of Mohenjo-daro, in Sindh, Pakistan. The settlement was inhabited between 4000 and 1700 BCE, and is considered to have been a centre ...
suggest that
sericulture Sericulture, or silk farming, is the cultivation of silkworm ''Bombyx mori'', the domestic silk moth, is an insect from the moth Moths are a paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last ...

sericulture
, employing
wild silkImage:Muga Silkworm.JPG, Antheraea assamensis, Muga silkworms on a som tree Wild silks have been known and used in many countries from early times, although the scale of production is far smaller than that from cultivated silkworms. Silk cocoons and ...
threads from native
silkworm ''Bombyx mori'', the domestic silk moth, is an insect from the moth Moths are a paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and all descendants of that ancestor excluding a ...

silkworm
species, existed in
South Asia South Asia is the southern region of Asia Asia () is 's largest and most populous , located primarily in the and . It shares the continental of with the continent of and the continental landmass of with both Europe and . Asia cov ...

South Asia
during the time of the
Indus Valley Civilisation , c. 2500 BCE. Terracotta Terracotta, terra cotta, or terra-cotta (; Italian language, Italian: "baked earth", from the Latin ''terra cocta''), a type of earthenware, is a clay-based ceramic glaze, unglazed or glazed ceramic, where the ...
(now in
Pakistan Pakistan, . Pronounced variably in English as , , , and . officially the Islamic Republic of Pakistan, is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a popul ...

Pakistan
and India) dating between 2450 BC and 2000 BC, while "hard and fast evidence" for silk production in China dates back to around 2570 BC. Shelagh Vainker, a silk expert at the
Ashmolean Museum The Ashmolean Museum of Art and Archaeology () on Beaumont Street, Oxford, England, is the world's second university museum (after the establishment of the Kunstmuseum Basel in 1661 by the University of Basel in Switzerland) and Britain's first pu ...
in Oxford, who sees evidence for silk production in China "significantly earlier" than 2500–2000 BC, suggests, "people of the Indus civilization either harvested silkworm cocoons or traded with people who did, and that they knew a considerable amount about silk." India is the second largest producer of silk in the world after China. About 97% of the raw mulberry silk comes from six Indian states, namely,
Andhra Pradesh Andhra Pradesh (English: Telugu: ) is a States and union territories of India, state in the south-eastern Coastal India, coastal region of India. It is the List of states and union territories of India by area, seventh-largest state by area c ...

Andhra Pradesh
,
Karnataka Karnataka (; ISO The International Organization for Standardization (ISO; ) is an international standard are technical standards developed by international organizations (intergovernmental organizations), such as Codex Alimentarius in f ...

Karnataka
,
Jammu and Kashmir Jammu is the winter capital of the Indian union territory of Jammu and Kashmir (union territory), Jammu and Kashmir. It is the headquarters and the largest city in Jammu district of the union territory. Lying on the banks of the river Tawi River ...
,
Tamil Nadu Tamil Nadu (; ) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspape ...

Tamil Nadu
,
Bihar Bihar (; ) is a states and union territories of India, state in eastern India. It is the list of states and union territories of India by population, third-largest state by population and list of states and union territories of India by area ...

Bihar
, and
West Bengal West Bengal (, Bengali Bengali or Bengalee, or Bengalese may refer to: *something of, from, or related to Bengal, a large region in South Asia * Bengalis, an ethnic and linguistic group of the region * Bengali language, the language they sp ...

West Bengal
. North Bangalore, the upcoming site of a $20 million "Silk City"
Ramanagara Ramanagara is a city and a city municipal council in the India India (Hindi: ), officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by population, second-most populous count ...
and
Mysore Mysore (), officially Mysuru (; Kannada: ಮೈಸೂರು), is a city in the southern part of the state of Karnataka, India. Mysore city is geographically located between 12° 18′ 26″ north latitude and 76° 38′ 59″ east longitude. I ...

Mysore
, contribute to a majority of silk production in Karnataka. In
Tamil Nadu Tamil Nadu (; ) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspape ...

Tamil Nadu
, mulberry cultivation is concentrated in the
Coimbatore Coimbatore ( ta, கோயம்புத்தூர், translit=kōyampuththūr, ), also known as Kovai or Covai (), is one of the major metropolitan cities in the Indian state India India (Hindi: ), officially the Republic o ...

Coimbatore
,
Erode Erode () is a city in the Indian state of Tamil Nadu. The seventh largest urban agglomeration in the state, after Chennai, Coimbatore, Madurai, Tiruchirapalli, Tiruppur and Salem, Tamil Nadu, Salem. It is also the administrative headquarters of ...

Erode
,
Bhagalpur Bhagalpur is a city of historical importance on the southern banks of the river Ganges in the Indian state of Bihar. It is the List of cities in Bihar by population, 3rd largest city of Bihar and also the headquarters of Bhagalpur district and B ...
i,
Tiruppur Tiruppur or Tirupur ( ) is a city in the Indian state of Tamil Nadu Tamil Nadu () is a States and union territories of India, state in southern India. Its capital and largest city is Chennai. Tamil Nadu lies in the southernmost part of the Ind ...
, Salem, and
Dharmapuri Dharmapuri, is a town in the western part of Tamil Nadu Tamil Nadu () is a States and union territories of India, state in southern India. Its capital and largest city is Chennai. Tamil Nadu lies in the southernmost part of the Indian subcont ...
districts.
Hyderabad Hyderabad ( , , ) is the capital and largest city of the India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the ...
,
Andhra Pradesh Andhra Pradesh (English: Telugu: ) is a States and union territories of India, state in the south-eastern Coastal India, coastal region of India. It is the List of states and union territories of India by area, seventh-largest state by area c ...

Andhra Pradesh
, and
Gobichettipalayam Gobichettipalayam () is the Selection grade municipality in the India India (Hindi: ), officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by population, second-most populous ...

Gobichettipalayam
,
Tamil Nadu Tamil Nadu (; ) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspape ...

Tamil Nadu
, were the first locations to have automated silk reeling units 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 northeastern 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 The word filament, which is descended from Latin ''filum'' meaning " thread", is used in English for a variety of thread-like structures, including: In commerce * Fiber Fiber or fibre (from la, fibra, links=no) is a natural or #Man-made f ...

filament
is too thin to use on its own so women combine many threads to produce a thicker, usable fiber. 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 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 Hydrogen peroxide is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by hav ...

hydrogen peroxide
. Once washed and dried, the silk is woven on a traditional hand-operated loom.


Bangladesh

The
Rajshahi Division Rajshahi Division ( bn, রাজশাহী বিভাগ) is one of the eight first-level administrative divisions of Bangladesh Divisions are the first-level administrative division in Bangladesh. There are currently 8 divisions of Bangla ...
of northern Bangladesh is the hub of the country's silk industry. There are three types of silk produced in the region: mulberry, endi, and tassar.
Bengal Bengal (; bn, বাংলা/বঙ্গ, translit=Bānglā/Bôngô, ) is a geopolitical, cultural and historical region located in South Asia, specifically in the eastern part of the Indian subcontinent at the apex of the Bay of Bengal, p ...

Bengal
i silk was a major item of international trade for centuries. It was known as Ganges silk in medieval Europe. Bengal was the leading exporter of silk between the 16th and 19th centuries.


Central Asia

The 7th century CE murals of Afrasiyab in
Samarkand fa, سمرقند , native_name_lang = , settlement_type = City , image_skyline = , image_alt = , image_caption = Clockwise from the top: The Reg ...

Samarkand
,
Sogdiana Sogdia () ( sog, soɣd) or Sogdiana was an ancient Iranian peoples, Iranian civilization between between the Amu Darya and the Syr Darya, and in present-day Uzbekistan, Tajikistan, Kazakhstan, and Kyrgyzstan. Sogdiana was also a province of the Ac ...
, show a Chinese Embassy carrying silk and a string of silkworm cocoons to the local Sogdian ruler.


Middle East

In the
Torah The Torah (; he, תּוֹרָה, "Instruction", "Teaching" or "Law") includes the first five books of the Hebrew Bible The Hebrew Bible or Tanakh (; Hebrew: , or ), is the Biblical canon, canonical collection of Hebrew language, Heb ...

Torah
, a scarlet cloth item called in Hebrew "sheni tola'at" שני תולעת – literally "crimson of the worm" – is described as being used in purification ceremonies, such as those following a leprosy outbreak (Leviticus 14), alongside
cedar wood Cedar is part of the English common name of many trees and other plants, particularly those of the genus ''Cedrus''. Some botanical authorities consider ''Cedrus'' the only Cedrus#Nomenclature, "true cedars". Many other species with similarly aro ...
and
hyssop ''Hyssopus officinalis'' or hyssop is a in the or mint family native to Southern , the , and the region surrounding the . Due to its purported properties as an , , and , it has been used in . Description Hyssop is a brightly coloured shrub o ...
(
za'atar Za'atar ( ; ar, زَعْتَر, ) is a culinary herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables Vegetables are parts of plants that are consumed by humans or other animals as f ...

za'atar
). Eminent scholar and leading medieval translator of
Jewish Jews ( he, יְהוּדִים ISO 259-2 , Israeli pronunciation ) or Jewish people are an ethnoreligious group and nation originating from the Israelites Israelite origins and kingdom: "The first act in the long drama of Jewish history is ...

Jewish
sources and books of the
Bible The Bible (from Koine Greek Koine Greek (, , Greek approximately ;. , , , lit. "Common Greek"), also known as Alexandrian dialect, common Attic, Hellenistic or Biblical Greek, was the koiné language, common supra-regional form of Gree ...

Bible
into
Arabic Arabic (, ' or , ' or ) is a Semitic language The Semitic languages are a branch of the Afroasiatic language family originating in the Middle East The Middle East is a list of transcontinental countries, transcontinental region ...

Arabic
, Rabbi
Saadia Gaon Sa'adiah ben Yosef Gaon ( ar, سعيد بن يوسف الفيومي ''Saʻīd bin Yūsuf al-Fayyūmi''; he, סעדיה בן יוסף אלפיומי גאון; alternative English Names: Rabbeinu Sa'adiah Gaon ("our Rabbi heSaadia Gaon"), often a ...
, translates this phrase explicitly as "crimson silk" – חריר קרמז حرير قرمز. In
Islamic Islam (; ar, اَلْإِسْلَامُ, al-’Islām, "submission
o God Oh God may refer to: * An exclamation; similar to "oh no", "oh yes", "oh my", "aw goodness", "ah gosh", "ah gawd"; see interjection An interjection is a word or expression that occurs as an utterance on its own and expresses a spontaneous feeling ...
) is an Abrahamic religions, Abrahamic monotheistic religion teaching that Muhammad is a Muhammad in Islam, messenger of God.Peters, F. E. 2009. "Allāh." In , ed ...
teachings, Muslim men are forbidden to wear silk. Many religious jurists believe the reasoning behind the prohibition lies in avoiding clothing for men that can be considered feminine or extravagant. There are disputes regarding the amount of silk a fabric can consist of (e.g., whether a small decorative silk piece on a cotton caftan is permissible or not) for it to be lawful for men to wear, but the dominant opinion of most Muslim scholars is that the wearing of silk by men is forbidden. Modern attire has raised a number of issues, including, for instance, the permissibility of wearing silk
necktie A necktie, or simply a tie, is a piece of cloth worn by men and women for decorative purposes around the neck The neck is the part of the body on many vertebrate Vertebrates () comprise all species of animal Animals (also called M ...

necktie
s, which are masculine articles of clothing.


Ancient Mediterranean

In the ''
Odyssey The ''Odyssey'' (; grc, Ὀδύσσεια, Odýsseia, ) is one of two major ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí ...
'', 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.
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of general and fundamental questio ...

Aristotle
wrote of ''
Coa vestis Coa vestis is an ancient Ancient history is the aggregate of past eventsWordNet Search – 3.0 ...
'', a wild silk textile from Kos. Sea silk from certain large sea shells was also valued. The Roman Empire knew of and traded in silk, and Chinese silk was the most highly priced luxury good imported by them. During the reign of emperor Tiberius, sumptuary laws were passed that forbade men from wearing silk garments, but these proved ineffectual. The Historia Augusta mentions that the third-century emperor Elagabalus was the first Roman to wear garments of pure silk, whereas it had been customary to wear fabrics of silk/cotton or silk/linen blends. Despite the popularity of silk, the secret of silk-making only reached Europe around AD 550, via the Byzantine Empire. Contemporary accounts state that monks working for the emperor Justinian I Smuggling of silkworm eggs into the Byzantine Empire, smuggled silkworm eggs to Constantinople from China inside hollow canes. All top-quality looms and weavers were located inside the Great Palace of Constantinople, Great 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.


Medieval and modern Europe

Italy was the most important producer of silk during the Medieval age. The first center to introduce silk production to Italy was the city of Catanzaro during the 11th century in the region of Calabria. The silk of Catanzaro supplied almost all of Europe and was sold in a large market fair in the port of Reggio Calabria, to Spanish, Venetian, Genovese, and Dutch merchants. Catanzaro became the lace capital of the world with a large silkworm breeding facility that produced all the laces and linens used in the Vatican. The city was world-famous for its fine fabrication of silks, velvets, damasks, and brocades. Another notable center was the Italian city-state of Republic of Lucca, Lucca which largely financed itself through silk-production and silk-trading, beginning in the 12th century. Other Italian cities involved in silk production were Genoa, Venice, and Florence. The Piedmont area of Northern Italy became a major silk producing area when water-powered silk throwing machines were developed. The Llotja de la Seda, Silk Exchange in Valencia from the 15th century—where previously in 1348 also ''perxal'' (percale) was traded as some kind of silk—illustrates the power and wealth of one of the great Mediterranean mercantile cities. Silk was produced in and exported from the province of Granada, Spain, especially the Alpujarras region, until the Morisco rebellions in Granada, Moriscos, whose industry it was, were expelled from Granada in 1571. Since the 15th century, silk production in France has been centered around the city of Lyon, France, Lyon where many mechanic tools for mass production were first introduced in the 17th century. James I of England, James I attempted to establish silk production in England, purchasing and planting 100,000 mulberry trees, some on land adjacent to Hampton Court Palace, but they were of a species unsuited to the silk worms, and the attempt failed. In 1732 John Guardivaglio set up a silk throwing enterprise at List of mills in Stockport, Logwood mill in Stockport; in 1744, Burton Mill was erected in Macclesfield; and in 1753 Old Mill was built in Congleton. These three towns remained the centre of the English silk throwing industry until silk throwing was replaced by silk waste, silk waste spinning. British enterprise also established silk filature in Cyprus in 1928. In England in the mid-20th century, raw silk was produced at Lullingstone Castle in Kent. Silkworms were raised and reeled under the direction of Zoe Lady Hart Dyke, later moving to Ayot St Lawrence in Hertfordshire in 1956. During World War II, supplies of silk for UK parachute manufacture were secured from the Middle East by Peter Gaddum. File:Vestido Javiera Carrera.jpg, Dress made from silk File:WLA vanda Bed lit a la polonaise.jpg, Bed covered with silk File:"Almgrensrosen"- ett 100 år gammalt mönster 2013.JPG, A hundred-year-old pattern of silk called "Almgrensrosen" File:Necktie knot.jpg, The
necktie A necktie, or simply a tie, is a piece of cloth worn by men and women for decorative purposes around the neck The neck is the part of the body on many vertebrate Vertebrates () comprise all species of animal Animals (also called M ...

necktie
originates from the cravat (early), cravat, a neckband made from silk


North America

Wild silk taken from the nests of native caterpillars was used by the Aztecs to make containers and as paper. Silkworms were introduced to Oaxaca Valley, Oaxaca from Spain in the 1530s and the region profited from silk production until the early 17th century, when the king of Spain banned export to protect Spain's silk industry. Silk production for local consumption has continued until the present day, sometimes spinning wild silk. King James VI and I, James I introduced silk-growing to the British colonies in America around 1619, ostensibly to discourage tobacco planting. The Shakers in Kentucky adopted the practice. The history of industrial silk in the United States is largely tied to several smaller urban centers in the Northeast region. Beginning in the 1830s, Manchester, Connecticut emerged as the early center of the silk industry in America, when the Cheney Brothers became the first in the United States to properly raise silkworms on an industrial scale; today the Cheney Brothers Historic District showcases their former mills. With the mulberry tree craze of that decade, other smaller producers began raising silkworms. This economy particularly gained traction in the vicinity of Northampton, Massachusetts and its neighboring Williamsburg, Massachusetts, Williamsburg, where a number of small firms and cooperatives emerged. Among the most prominent of these was the cooperative utopian Northampton Association for Education and Industry, of which Sojourner Truth was a member. Following the destructive Mill River Flood of 1874, one manufacturer, William Skinner (manufacturer), William Skinner, relocated his mill from Williamsburg to the then-new city of Holyoke. Over the next 50 years he and his sons would maintain relations between the American silk industry and its counterparts in Japan, and expanded their business to the point that by 1911, the Skinner Mill complex contained the largest silk mill under one roof in the world, and the brand Skinner Fabrics had become the largest manufacturer of silk satins internationally. Other efforts later in the 19th century would also bring the new silk industry to Paterson, New Jersey, with several firms hiring European-born textile workers and granting it the nickname "Silk City" as another major center of production in the United States. World War II interrupted the silk trade from Asia, and silk prices increased dramatically. U.S. industry began to look for substitutes, which led to the use of synthetic fiber, synthetics such as nylon. Synthetic silks have also been made from lyocell, a type of cellulose fiber, and are often difficult to distinguish from real silk (see spider silk for more on synthetic silks).


Malaysia

In Terengganu, which is now part of Malaysia, a second generation of silkworm was being imported as early as 1764 for the country's silk textile industry, especially songket. However, since the 1980s, Malaysia is no longer engaged in sericulture but does plant mulberry trees.


Vietnam

In Vietnamese legend, silk appeared in the first millennium AD and is still being woven today.


Production process

The process of silk production is known as
sericulture Sericulture, or silk farming, is the cultivation of silkworm ''Bombyx mori'', the domestic silk moth, is an insect from the moth Moths are a paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last ...

sericulture
. The entire production process of silk can be divided into several steps which are typically handled by different entities. Extracting raw silk starts by cultivating the silkworms on mulberry leaves. Once the worms start pupating in their cocoons, these are dissolved in boiling water in order for individual long fibres to be extracted and fed into the spinning reel. To produce 1 kg of silk, 104 kg of mulberry leaves must be eaten by 3000 silkworms. It takes about 5000 silkworms to make a pure silk kimono. The major silk producers are
China China (), officially the People's Republic of China (PRC; ), is a country in East Asia East Asia is the eastern region of Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere ...

China
(54%) and
India India, officially the Republic of India (Hindi Hindi (Devanagari: , हिंदी, ISO 15919, ISO: ), or more precisely Modern Standard Hindi (Devanagari: , ISO 15919, ISO: ), is an Indo-Aryan language spoken chiefly in Hindi Belt, ...

India
(14%). Other statistics: The environmental impact of silk production is potentially large when compared with other natural fibers. A life-cycle assessment of Indian silk production shows that the production process has a large carbon and water footprint, mainly due to the fact that it is an animal-derived fiber and more inputs such as fertilizer and water are needed per unit of fiber produced.


Properties


Physical properties

Silk fibers from the ''Bombyx mori'' silkworm have a triangle, triangular cross section (geometry), cross section with rounded corners, 5–10 μm wide. The fibroin-heavy chain is composed mostly of beta-sheets, due to a 59-mer amino acid repeat sequence with some variations. The flat surfaces of the fibrils reflect light at many angles, giving silk a natural sheen. The cross-section from other silkworms can vary in shape and diameter: crescent-like for ''Anaphe'' and elongated wedge for ''tussah''. Silkworm fibers are naturally extruded from two silkworm glands as a pair of primary filaments (brin), which are stuck together, with sericin proteins that act like glue, to form a bave. Bave diameters for tussah silk can reach 65 μm. See cited reference for cross-sectional SEM photographs. Silk has a smooth, soft texture that is not slippery, unlike many synthetic fibers. Silk is one of the strongest natural fibers, but it loses up to 20% of its strength when wet. It has a good moisture regain of 11%. Its Elasticity (physics), 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. One example of the durable nature of silk over other fabrics is demonstrated by the recovery in 1840 of silk garments from a HMS Royal George (1756), wreck of 1782: 'The most durable article found has been silk; for besides pieces of cloaks and lace, a pair of black satin breeches, and a large satin waistcoat with flaps, were got up, of which the silk was perfect, but the lining entirely gone ... from the thread giving way ... No articles of dress of woollen cloth have yet been found.' Silk is a poor conductor of electricity and thus susceptible to static cling. Silk has a high emissivity for infrared light, making it feel cool to the touch. Unwashed silk chiffon may shrinkage (fabric), shrink up to 8% due to a relaxation of the fiber macrostructure, so silk should either be washed prior to garment construction, or dry cleaning, dry cleaned. Dry cleaning may still shrink the chiffon up to 4%. Occasionally, this shrinkage can be reversed by a gentle steaming with a press cloth. There is almost no gradual shrinkage nor shrinkage due to molecular-level deformation. Natural and synthetic silk is known to manifest piezoelectricity, piezoelectric properties in proteins, probably due to its molecular structure. Silkworm silk was used as the standard for the denier (measure), denier, a measurement of linear density in fibers. Silkworm silk therefore has a linear density of approximately 1 den, or 1.1 dtex.


Chemical properties

Silk emitted by the silkworm consists of two main proteins, sericin and
fibroin Fibroin is an insoluble protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one location to another. Prote ...
, fibroin being the structural center of the silk, and serecin being the sticky material surrounding it. Fibroin is made up of the amino acids glycine, Gly-serine, Ser-Gly-alanine, Ala-Gly-Ala and forms beta sheet, 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 allows tight packing. This is because glycine's R group is only a hydrogen and so is not as sterically constrained. The addition of alanine and serine makes the fibres strong and resistant to breaking. This tensile strength is due to the many interceded hydrogen bonds, and when stretched the force is applied to these numerous bonds and they do not break. Silk resists most mineral acids, except for sulfuric acid, which dissolves it. It is yellowed by perspiration. Chlorine bleach will also destroy silk fabrics.


Variants


Regenerated silk fiber

RSF is produced by chemically dissolving silkworm cocoons, leaving their molecular structure intact. The silk fibers dissolve into tiny thread-like structures known as microfibrils. The resulting solution is extruded through a small opening, causing the microfibrils to reassemble into a single fiber. The resulting material is reportedly twice as stiff as silk.


Applications


Clothing

Silk's absorption (chemistry), 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, necktie, ties, blouses, formal dresses, high-fashion clothes, lining (sewing), lining, lingerie, pajamas, robes, formal wear, dress suits, sun dresses, and Eastern folk costumes. For practical use, silk is excellent as clothing that protects from many biting insects that would ordinarily pierce clothing, such as mosquitoes and horse-fly, horseflies. Fabrics that are often made from silk include charmeuse, habutai, chiffon (fabric), chiffon, taffeta, crêpe (textile), crêpe de chine, dupioni, noil, tussah, and shantung (fabric), shantung, among others.


Furniture

Silk's attractive lustre and drape makes it suitable for many furnishing applications. It is used for upholstery, wall coverings, window treatments (if blended with another fiber), carpet, rugs, bedding, and wall hangings.


Industry

Silk had many industrial and commercial uses, such as in parachutes, bicycle tires, silk comforter, comforter filling, and artillery gunpowder bags.


Medicine

A special manufacturing process removes the outer 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, which has been used for skin conditions including eczema. New uses and manufacturing techniques have been found for silk for making everything from disposable cups to drug delivery systems and holograms.


Biomaterial

Silk began to serve as a biomedicine, biomedical material for sutures in surgeries as early as the second century CE. In the past 30 years, it has been widely studied and used as a biomaterial due to its strength of materials, mechanical strength, biocompatibility, tunable degradation rate, ease to load cellular growth factors (for example, BMP-2), and its ability to be processed into several other formats such as films, gels, particles, and scaffolds. Silks from ''Bombyx mori'', a kind of cultivated silkworm, are the most widely investigated silks. Silks derived from ''Bombyx mori'' are generally made of two parts: the silk fibroin fiber which contains a light chain of 25kDa and a heavy chain of 350kDa (or 390kDa) linked by a single disulfide bond and a glue-like protein, sericin, comprising 25 to 30 percentage by weight. Silk fibroin contains hydrophobic beta sheet blocks, interrupted by small hydrophilic groups. And the beta-sheets contribute much to the high mechanical strength of silk fibers, which achieves 740 MPa, tens of times that of polylactic acid, poly(lactic acid) and hundreds of times that of collagen. This impressive mechanical strength has made silk fibroin very competitive for applications in biomaterials. Indeed, silk fibers have found their way into tendon tissue engineering, where mechanical properties matter greatly. In addition, mechanical properties of silks from various kinds of silkworms vary widely, which provides more choices for their use in tissue engineering. Most products fabricated from regenerated silk are weak and brittle, with only ≈1–2% of the mechanical strength of native silk fibers due to the absence of appropriate secondary and hierarchical structure,


Biocompatibility

Biocompatibility, i.e., to what level the silk will cause an immune response, is a critical issue for biomaterials. The issue arose during its increasing clinical use. Wax or silicone is usually used as a coating to avoid fraying and potential immune responses when silk fibers serve as suture materials. Although the lack of detailed characterization of silk fibers, such as the extent of the removal of sericin, the surface chemical properties of coating material, and the process used, make it difficult to determine the real immune response of silk fibers in literature, it is generally believed that sericin is the major cause of immune response. Thus, the removal of sericin is an essential step to assure biocompatibility in biomaterial applications of silk. However, further research fails to prove clearly the contribution of sericin to inflammatory responses based on isolated sericin and sericin based biomaterials. In addition, silk fibroin exhibits an inflammatory response similar to that of tissue culture plastic in vitro when assessed with human mesenchymal stem cells (hMSCs) or lower than collagen and PLA when implant rat MSCs with silk fibroin films in vivo. Thus, appropriate degumming and sterilization will assure the biocompatibility of silk fibroin, which is further validated by in vivo experiments on rats and pigs. There are still concerns about the long-term safety of silk-based biomaterials in the human body in contrast to these promising results. Even though silk sutures serve well, they exist and interact within a limited period depending on the recovery of wounds (several weeks), much shorter than that in tissue engineering. Another concern arises from biodegradation because the biocompatibility of silk fibroin does not necessarily assure the biocompatibility of the decomposed products. In fact, different levels of immune responses and diseases have been triggered by the degraded products of silk fibroin.


Biodegradability

Biodegradability (also known as biodegradation)—the ability to be disintegrated by biological approaches, including bacteria, fungi, and cells—is another significant property of biomaterials today. Biodegradable materials can minimize the pain of patients from surgeries, especially in tissue engineering, there is no need of surgery in order to remove the scaffold implanted. Wang et al. showed the in vivo degradation of silk via aqueous 3-D scaffolds implanted into Lewis rats. Enzymes are the means used to achieve degradation of silk in vitro. Protease XIV from Streptomyces griseus and α-chymotrypsin from bovine pancreases are the two popular enzymes for silk degradation. In addition, gamma radiation, as well as cell metabolism, can also regulate the degradation of silk. Compared with synthetic biomaterials such as polyglycolides and polylactides, silk is obviously advantageous in some aspects in biodegradation. The acidic degraded products of polyglycolides and polylactides will decrease the pH of the ambient environment and thus adversely influence the metabolism of cells, which is not an issue for silk. In addition, silk materials can retain strength over a desired period from weeks to months as needed by mediating the content of beta sheets.


Genetic modification

Genetic modification of domesticated silkworms has been used to alter the composition of the silk. As well as possibly facilitating the production of more useful types of silk, this may allow other industrially or therapeutically useful proteins to be made by silkworms.


Cultivation

Silk moths lay eggs on specially prepared paper. The eggs hatch and the caterpillars (silkworms) are fed fresh
mulberry ''Morus'', a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In ...

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 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 heat the cocoons to kill them, leaving some to metamorphosis, 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 by boiling them, sericulture has been criticized by animal welfare and rights activists. Mohandas Karamchand Gandhi, Mahatma Gandhi was critical of silk production based on the Ahimsa philosophy, which led to the promotion of cotton and Ahimsa silk, a type of
wild silkImage:Muga Silkworm.JPG, Antheraea assamensis, Muga silkworms on a som tree Wild silks have been known and used in many countries from early times, although the scale of production is far smaller than that from cultivated silkworms. Silk cocoons and ...
made from the cocoons of wild and semi-wild silk moths. Since silk cultivation kills silkworms, People for the Ethical Treatment of Animals (PETA) urges people not to buy silk items.


See also

*Art silk *Bulletproofing *International Year of Natural Fibres *Mommes *Rayon *Sea silk *Silk waste *Sinchaw *Spider silk


References


Citations


Bibliography

* * Hill, John E. (2004)
''The Peoples of the West from the Weilüe''
魏略 ''by Yu Huan'' 魚豢'': A Third Century Chinese Account Composed between 239 and 265 AD.'' Draft annotated English translation. Appendix E. * Hill, John E. (2009) ''Through the Jade Gate to Rome: A Study of the Silk Routes during the Later Han Dynasty, 1st to 2nd centuries CE''. BookSurge, Charleston, South Carolina. . * Magie, David (1924). ''Historia Augusta Life of Heliogabalus''. Loeb Classical Texts No. 140: Harvard University Press..


Further reading

* Feltwell, John (1990). ''The Story of Silk''. Alan Sutton Publishing. . * Good, Irene (December 1995). "On the question of silk in pre-Han Eurasia". ''Antiquity''. Vol. 69, Number 266. pp. 959–968. * Kuhn, Dieter (1995). "Silk Weaving in Ancient China: From Geometric Figures to Patterns of Pictorial Likeness." ''Chinese Science''. 12. pp. 77–114. * Xinru Liu, Liu, Xinru (1996). ''Silk and Religion: An Exploration of Material Life and the Thought of People, AD 600–1200''. Oxford University Press. * Xinru Liu, Liu, Xinru (2010). ''The Silk Road in World History''. Oxford University Press. ; (pbk). * * Sung, Ying-Hsing. 1637. ''Chinese Technology in the Seventeenth Century – T'ien-kung K'ai-wu''. Translated and annotated by E-tu Zen Sun and Shiou-chuan Sun. Pennsylvania State University Press, 1966. Reprint: Dover, 1997. "Chapter 2. Clothing materials". * Kadolph, Sara J. (2007). ''Textiles'' (10th ed.). Upper Saddle River: Pearson Prentice Hall. pp. 76–81. * Ricci, G.; et al. (2004). "Clinical Effectiveness of a Silk Fabric in the Treatment of Atopic Dermatitis". ''British Journal of Dermatology''. Issue 150. pp. 127–131.


External links


References to silk by Roman and Byzantine writersHistory of traditional silk in martial arts uniforms
*[https://phys.org/news/2009-09-thread-fabric-insect-silks.html New thread in fabric of insect silks, physorg.com] {{Authority control Silk, Animal glandular products Articles containing video clips Biomaterials Chinese inventions Insect products Silk Road Woven fabrics