Silk and Its Types

Different types of silks

Silk and its types:

Silk is a smooth, lustrous and elastic filament of small diameter which is obtained from cocoons spun by a wide variety of silkworm which is species of caterpillar. It is the only natural fiber in filament form. Its physical characteristics are totally different from wool and allied fiber.
Silk differs from all other natural fibers in that it is composed of an organized structure as the vegetable and other animal fibers, but is a structure less secretion in the form of a continuous thread. Silk is refereed as ‘The Queen Textiles’ which spells luxury, comfort and elegance.
Silk production is regarded as an important parameter for economic development of a country as it is a labor intensive and high income generating industry that churns out value added products of economic importance. In India, Silk is cultivated in southern and eastern part of the countries.

Chemical composition of raw silk fiber: 
  • Fibroin  70-75%
  • Sericine 20-25%
  • Waxy substance 2-3%
  • Natural colors 1-1.5%

Characteristics of Silk:

It is the strongest natural fiber and has excellent luster.It retains its shape and is relatively smooth.

It absorbs good amount of moisture.

It can be easily dyed.
It is cool to wear in the summer yet warm to wear in winter.
It is versatile and very comfortable.

Physical properties of Silk:
Strength: Silk is strong textile fiber that is, the fiber of same diameter. It I weaker when wet than when dry, silk fiber can sustain dead weight f 5-28grams before breaking.
Elasticity: Silk is elastic more than linen, cotton or rayon and has good resilience.
Hygroscopic moisture: Moisture absorption of silk is about 10-11% which is higher than cotton, linen and rayon. It absorbs perspiration and oil from skin.
Effect of heat: Unlike cotton at 110 degree Celsius, silk turns yellow after 15 min in an oven. It may turn yellow with the use of hot iron.
Effect of light and mildew: Silk is not resistant to light as compared to cotton and mildew is often fund on silk. It is relatively resistant to other bacteria and fungi.

Chemical properties of silk:

Effect of acids: Acids such as sulphuric acid, hydrochloric acid and nitric acid do not affect the silk if they are in the dilute state. It is more resistant to acids as compared to vegetable fibers.
Effect of alkalis: Concentration solutions of alkalis such as caustic soda of caustic potash dissolve silk. It is advisable to use a mild soap with no alkalis for washing silk fabrics.
Affinity for dyestuff: Silk has a natural affinity for dye. Basics, acids and direct dyes are all used on silks.
Action of bleaches: care should be taken to control bleaching conditions. Hydrogen peroxide and per borates bleaches are used when silk requires beaching.

Types of Silk

Silk is classified into two main categories:
Mulberry Silk
Non-mulberry silk: which is further classified as- Tasar, Eri and Muga

Mulberry (Cultivated) Silk:
It is main type of silk which is obtained from silkworm that feeds on leaves of mulberry plant.
The bulk of commercial silk produced in the World comes from this variety.
Mulberry silk comes from the silkworm, Bombyx Mori which solely feeds on the leaves of mulberry plant.
This type of silk accounts for 80% of Nation’s total production.
Most fabulous silk materials are produced out of this variety. Sarees from Kashmir, Banaras, and Mysore belong to this variety.

Tasar Silk (Non-mulberry silk):
Among the commercially important varieties of wild silk, Tasar is the most popular. Tasar silk worms are reared in tropical and temperate zones.
The cocoons are generally yellow or grey and the female spins larger than male.
The Tasar silkworm is very different from the domesticated mulberry silkworm and the insects mostly live in the wild on bushes and trees on which they feed. It is coarser as compared to mulberry silk. 

Muga Silk: 
The golden yellow Muga silk is secreted by a semi-domesticated multivoltine species. The cocoon is yellow or glossy white.
Muga silk is extracted from a rare species of insects which is not found anywhere in the World expect in the North Eastern part of India.
Muga is obtained from the silk worm called Antheraea Assama

Eri Silk:
Eri worms feeds on leaves of varieties of plant, among them castor is preferred variety of plant.
This is the only completely domesticated non-mulberry variety. Its silk is spun as it cannot be reeled.

Silk fabric care:
It is advisable to dry clean the silk fabrics. While hand washing, it should be washed in cold water and us small amount of soap or detergent. After washing it, rinse with cold water. If pressing is needed use an all cotton iron board cover with low or moderate steam setting and press on the wrong side of the fabric while ironing.

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