Silk is a natural protein fibre, some forms of which can be woven into textiles. A variety of silks, produced by caterpillars or silkworms. 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.
Types of Silk Fibre
We will describe the types of silk fibre focusing on two topics. These two pint are , according to industrial uses. Other is cocoons obtained from different species of silkworms which in turn feed on a number of food plants. First we will describe the types of silk fibre according to industrial uses.
According to industrial uses
It comes from the cocoon which 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.
Silk made from wild silkworms is called tussah silk. The natural color of tussah silk is usually not white. It has shades of pale beige, brown and grey. It is usually coarser than cultivated silk.
It is also known as mulberry silk which is produced by domesticated silkworm. It is raised on diet of mulberry leaves almost exclusively softer, finer and more lustrous than tussah silk. This silk produces shades of white product.
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.
Silk made from broken cocoon (from which the moths have already emerged) and short fibres. It feels more like cotton.
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. Thus it is known as weighted 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 it is called pure silk. Pure silk is exclusively soft and possesses fine luster.
Types of Silk Fibre
According to cocoons and silkworms
There are four major types of silk of commercial importance, obtained from different species of silkworms which in turn feed on a number of food plants. These are:
Except mulberry, other varieties of silks are generally termed as non-mulberry silks. India has the unique distinction of producing all these commercial varieties of silk.
The bulk of the commercial silk produced in the world comes from this variety and often silk generally refers to mulberry silk. Mulberry silk comes from the silkworm, Bombyx mori L. Which is solely feeds on the leaves of mulberry plant. These silkworms are completely domesticated and reared indoors. In India, the major mulberry silk producing states are Karnataka, Andhra Pradesh, West Bengal, Tamil Nadu and Jammu & Kashmir. These accounts for 92 % of country’s total mulberry raw silk production.
Tasar (Tussah) is copperish colour. Coarse silk mainly used for furnishings and interiors. It is less lustrous than mulberry silk. But has its own feel and appeal. Tasar silk is generated by the silkworm, Antheraea mylitta. It is mainly thrive on the food plants Asan and Arjun. The rearings are conducted in nature on the trees in the open. In India, tasar silk is mainly produced in the states of Jharkhand, Chattisgarh and Orissa. Besides Maharashtra, West Bengal and Andhra Pradesh . Tasar culture is the main stay for many a tribal community in India.
Oak Tasar: (also known as temperate tasar)
Filaments of the cocoons of this silk from Bihar were originally unwound and plied together on a mud pot, or Matka ( Today, they are alikely to be reeled on a woman’s thigh).
From the four basic categories of silks the other silk fabrics are
- China Silk
- Organza silk
- Cotton silk
- Crepe silk
- Bracade silk
- Taffeta silk
- Thai silk
- Satin silk
- Blended silk
Author: Asif Hossain
Member of (A.1) Team