Different Types of Silk Fibres
Rakibul Islam Khan
Department of Textile Engineering
Ahsanullah University of Science & Technology (AUST)
Email: pl_20in@hotmail.com
Silk Fibre:
Silk is a natural protein fiber, some forms of which can be woven into textiles. It is obtained from the cocoon of the silkworm larva, in the process known as sericulture. A variety of silks, produced by caterpillars and mulberry silkworm, have been known and used in China, South Asia, and Europe since ancient times. The strands of raw silk as they are unwound from the cocoon consist of the two silk filaments mixed with sericin and other materials. About 75 % of the strand is silk i.e. fibroin and 23 % is sericin; the remaining materials consist of fat and wax (1.5 %) and mineral salts (0.5 %). As a natural protein fiber silk has a significant attraction towards natural dyes.
Silk is the longest and thinnest natural filament fiber with the longest filament around 3000 yards. It is relatively lustrous, smooth, lightweight, strong and elastic. It is essentially composed of protein fiber and is naturally a white-colored fiber. Silk is a poor conductor of electricity and thus susceptible to static cling.
Different Types of Silk Fibres:
Silk fibers can be classified based on their source, production method, and region. Silk is categorized based on origin as Chinese, Indian, Japanese and European silks. Chinese silk is indigenous to China and they produce one of the finest silk and are white, golden yellow, green, red or beige in colour. Silk fibres come in various types, each with unique characteristics and uses. Here are the main types of silk fibres:
a) Mulberry silk or Domestic silk:
The mulberry silkworm belongs to the species Bombyx mori and about 95% of the world’s production is of this species. It is also known as mulberry silk which is produced by domesticated silkworm raised on diet of mulberry leaves almost exclusively softer, finer and more lustrous than tussah silk. It typically comes in a white or off-white colour. This silk produces shades of white product. Mulberry silk is the most common and highest quality silk fibre. For making luxury silk fabric mulberry silk is used. Major mulberry silk-producing countries are China and India – China produces 80–82% of the world production and India about 15–18%.
b) Tussah silk or Wild silk:
Tasar (tussah) is coarse silk of copperish colour, mainly used for furnishings and interiors. It is less lustrous than mulberry silk, but has its own feel and appeal. Silk made from wild silkworms is called tussah silk. Tussah or tussar silk is perhaps best known as a wild silk that is collected in the forests of India and other countries in South Asia. The natural color of tussah silk is usually not white, but shades of pale beige, brown and grey. It is usually coarser and stronger texture than cultivated silk. Tussah silk is often used in traditional Indian garments and is prized for its rich texture.
c) Muga silk:
This is a golden-yellow-colored silk. It is obtained from the semidomesticated silkworm, which feeds on the aromatic leaves of som and soalu plants. Muga silk is an exclusive variety of silk produced in Assam, India. It has a unique sheen that becomes even more lustrous with washing. Muga silk is a high-value product and is used in the manufacture of products such as sarees, mekhalas and chaddars.
d) Eri silk:
This is got from the domesticated silkworm. It feeds mainly on castor leaves. It is known for its soft, warm, and wool-like texture, making it a popular choice for colder climates. Eri silk is heavier and more durable in comparison to mulberry silk. Unlike other silks, Eri silk is often harvested without killing the silkworm, earning it the name “peace silk.” Eri silk has both the softness of other silks and the insulating properties of wool, making it a promising silk species for further commercial development.
e) Spider silk:
Spider silk is another non-insect variety. It is soft and fine, but also strong and elastic. Archanids to which spiders belong consists of about 37,000 species and are known to produce silk with extraordinary properties. Different species of spiders produce silk from different glands such as ampullate (dragline), flagelliform etc. The extraordinary properties of spider silks depend heavily on the species and glands and shows substantial variations.
Spider silk is the most expensive variety of silk. It is incredibly strong and elastic, with tensile strength comparable to steel. Despite its impressive properties, spider silk is not widely used commercially due to the difficulty in producing it in large quantities. Because of the high cost of production, spider silk is not used in the textile industry; however, durability, resistance to extremes of temperature and humidity make it indispensable for cross-hairs in optical instruments Manufacturers use spider silk to produce microscopes, bulletproof vests, etc.
f) Marine silk:
Unique and distinct silks have been discovered in several marine animals but are probably the least studied among all the sources of silk. Marine silk, also known as byssus or sea silk, is a rare and ancient type of silk produced by certain marine mollusks, particularly the Pinna nobilis, a large Mediterranean bivalve. The byssus is a fibrous material that the mollusk secretes to anchor itself to the sea floor. These fibers are collected and processed to create a unique and luxurious textile.
g) Artificial silk:
Artificial silk or art silk, is a synthetic or man-made silk that mimics the appearance and texture of natural silk but typically costs less to produce. It is made by chemically processing wood pulp. Although artificial silk imitates the look and feel of silk, it is not as strong or durable as the real thing. Artificial silk is widely used in fashion and home textiles as a cost-effective substitute for silk.
h) Reeled silk or Thrown silk:
It is term for silk fibre that is unwound from the silkworm cocoon. It is the most fine silk, the fibres are very long, shiny and of great strength.
i) Raw silk:
Silk fibre as it comes from the cocoon is coated with a protective layer called silk gum, or sericin. The silk gum is dull and stiff. Silk with all of its gum is termed raw silk.
j) Spun silk:
Silk made from broken cocoon (from which the moths have already emerged) and short fibres, feels more like cotton.
k) Weighted silk:
When yarns are prepared for weaving, the skeins of yarn are boiled in a soap solution to remove the natural silk gum or sericin. The silk may lose from 20 to 30 percent of its original weight as a result of boiling. As silk has a great affinity for metallic salts such as those of tin and iron, the loss of weight is replaced through the absorption of metals. Thus a heavier fabric can be made at a lower price than that of pure silk, which is known as weighted silk.
l) Pure silk:
If the natural gum or sericin is removed from the silk and no further material is added to increase the weight of the fibre, i.e. silk containing no metallic weighting is called pure silk. Pure silk is exclusively soft and possesses fine luster.
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
