Silk is a natural protein fibre. It is produced by the silk worm which produces cocoon. Silk fiber is extracted from cocoon. Silk are mainly two types i.e. cultivated silk and wild silk. Cultivated silk is better than wild silk. Main properties of silk fibre are as follows:

1. Length: Length of silk fibre varies from 400 to 700 meters.

2. Fineness: It is very fine fibre. Fineness varies from 11 to 12 microns.

3. Cross-section: Its cross-section is triangular.

4. Strength: Strength of silk fibre is reasonably good. Its tenacity varies from 2.4 to 5.1 g/den.

5. Stretch and elasticity: Extensibility is 15% when at break. Recovery from stretch is 90% when extension is up to 2%.

6. Resiliency: resiliency is moderate.

7. Abrasion Resistance: Resiliency good.

8. Moisture Regain: 11%.

9. Effect Chemical properties:

· Effect of bleaches: Damages by the effects of strong bleaching agents. Hence, perfectly white silk fabric is not seen.

· Effect off acid & alkali: Strong mineral acid damages silk fibre & strong alkali also damages silk.

· Effect of organic solvent: Silk is unaffected by the organic solvent hence dry cleaning is safe.

· Dye-ability: Dyeing at low temperature by direct, acid, basic, vat & reactive dyes could be done.

· Biological properties: Normally unaffected by fungus, moths & insects.

· Flammability: Burns slowly when contact with flame. It also self extinguishes.

· Electrical & thermal conductivity: Heat and current flow rate is slow.

· Use: silk is widely used all over the world. It is used for children’s wear, ladies wears, tie, suits etc purposes.