Presented by:

T. SrivaniAsst. Prof., DFT

ABOUT SILK……….Fine, strong, soft, lustrous fibre produced by

silkworms.A natural protein fibre.The best-known type of silk is obtained from cocoons

made by the larvae of the mulberry silkworm Bombyx mori reared in captivity (sericulture).

The shimmering appearance for which silk is prized comes from the fibres' triangular prism-like cross section which allows silk cloth to refract incoming light at different angles.

It is a smooth, lustrous, elastic and fine filament, the length of which varies from cocoon to cocoon and species to species.

HISTORY OF THE USE OF SILKChinese are using silk since 27th century B.C.Became a valuable commodity in Greece and

Rome.During Roman Empire, silk was sold for its

weight in gold.SILK Production-Secret of China Chinese domesticated silkworms, fed them with mulberry leaves and unwound cocoons to form silk strands . The Chinese women

domesticating silkworms for obtaining silk from its cocoons.

Silk was transported to Rome through Silk road, bringing great wealth to China. They never revealed the production process .

Christian monks finally broke China’s monopoly of the silk production by smuggling silkworm eggs out of the country, and soon other countries started to produce their own silk.

PRODUCTION IN INDIA

STATISTICS                                                                       Review Of Silk Exports & Imports                                         

                               TABLE - I :  TOTAL EXPORT EARNINGS OF SILK ITEMS

   (Unit : Value in Crore Rs. & Million US $)

Itemwise Exports

    March April to March

    2008 2007 2007-2008 2006-2007

Rs US $ Rs US $ Rs US $ Rs US $

Natural Silk Yarn,Fabrics,Madeup 175.97 43.60 252.46 57.34 1525.68 378.87 2365.34 522.74

Readymade Garments 174.84 43.32 59.05 13.41 1043.47 259.12 817.87 180.74

Silk Carpet 1.29 0.32 3.64 0.83 56.26 13.97 132.36 29.25

Silkwaste 0.55 0.14 1.90 0.43 11.94 2.96 22.78 5.03

Total 352.65 87.38 317.05 72.01 2637.35 654.92 3338.35 737.76

 Provisional Figures

 Source : Foreign Trade Statistics of India (Principal Commodities & Countries), DGCI&S, Kolkata

SILK AS A FABRICSILK is the fabric that makes its own

statement.Silk garments are prized for their versatility,

wear ability and comfort.Silk has got amazing lustre and shine, which

makes it a royal fabric.

PHYSICAL PROPERTIESCross section- Triangular with rounded corners. This allows light to hit at many different angles, giving shine & brightness.Texture- Smooth and soft but not slippery. Strength- loses up to 20% of its strength when

wet. Elasticity- Moderate to poor, if elongated even a

small amount it remains stretched. Thermal properties- Weakened if exposed to too

much sunlight.

Effect of insects- Attacked by insects, especially if left dirty.

Comfort- Good absorbency. Comfortable in the summer and warm in the winter.

Appearance Retention- Moderate resistance to wrinkling. Electrical properties- Poor conductor of electricity and thus susceptible to static cling.

Shrinkage-Unwashed silk chiffon may shrink up to 8% due to a relaxation of the fibre macrostructure.

Aesthetics- Cultivated silk is a beautiful luxurious fibre with a smooth luxurious hand. Wild silks are duller and have a more coarse hand and texture.

Durability- Moderate abrasion resistance.

PHYSICAL PROPERTIES

PHYSICAL PROPERTIES ELASTICITY - Silk requires 0.90 gm tension per denier to stretch 1% at

65% R.H. - Wool requires only 0.32 gm tension per denier,

approximately 1/3rd MOISTURE TAKE-UP - moisture regain is 11% - after degumming regain is only 9% ELECTRIC PROPERTIES - Poor conductor of electricity - accumulates a static charge by friction, which

makes it difficult to handle in manufacturing process. SCROOP : The cracking sound emitted when the fibre is squeezed and

pressed. - scroop is not an inherent property of silk - silk can be scrooped by dipping it in dilute acetic or tartaric

acid.

CHEMICAL PROPERTIES• ACTION OF HEAT - can be heated to 140°C, at 170°C it rapidly disintegrates - degummed fibres on burning produce an odour like burning hair or wool, leaving a black crisp and easily crushable ash. • ACTION OF SUNLIGHT

- can lose upto 50% of its original strength when exposed to UV rays

• ACTION OF WATER- highly absorbent fibre- hard and impure water are the sources of contamination for silk

goods

• ACTION OF ACIDS- readily absorbs dilute acids which increases the lustre- readily affected by action of conc. Acids

• ACTION OF ALKALIES- less sensitive to dilute alkalies- on treatment with strong alkalies, the fibre dissolves

TYPES OF SILK Domestic silk Mulberry silk: White to yellow coloured. Fine and

used for apparel. Wild silk Muga silk: Golden yellow coloured. Obtained

from semi domesticated silkworm, fed on Som and Soalu leaves.

Eri silk: Obtained from domesticated silkworm, fed on Castor leaves.

Tussar silk or Kosa silk: Valued for purity and texture.

Domesticated silk comes from “Bombyx mori”, which feeds on mulberry leaves.

Wild silk is obtained from different caterpillars Tussar silk from genus ‘Antheria’ or ‘Attacus’Indian tussar from ‘Antheria Mylitta’, which feeds on leaves of Sal, Asam, Arjun, Bear or Kul.Muga silk from ‘Antheria Assama’, which feeds on Sum and Hualin leaves.Eri silk from ‘Attacus Racine’, which feeds on castor leaves.Chinese wild silk from ‘Antheria Pernyi’Japnese from ‘Antheria Yamamai’SERICULTURE: Technique of cultivating the silk cocoons or silk worms.

TYPES OF SILKMULBERY SILK:-

Mulberry silk comes from the silkworm, Bombyx mori L. which solely feeds on the leaves of mulberry plant.

TASAR SILK:- Tasar (Tussah) is copperish colour, coarse silk mainly used for furnishings and interiors.

TYPES OF SILK3. MUGA SILK:- This

golden yellow colour silk is prerogative  of India and the pride of Assam state. It is obtained from semi-domesticated multivoltine silkworm, Antheraea assamensis.

4.ERI SILK:- Also known as Endi or Errandi, Eri is a multivoltine silk spun from open-ended cocoons,

Mulberry silk

Tussar silkMuga silk

Eri silk

PRODUCTION OF SILKThe production of cultivated silk is known as sericulture.

Cultivation of mulberry silk

A silk moth lays eggs.

Silkworm fed on mulberry leaves.

35 days old silkworms are 10,000 times heavier than when they hatched. They are now ready to spin a silk cocoon.

A cocoon.

Production stages

• The silk is produced in two glands in the silkworm’s head and forced out in liquid form through openings called spinnerets.

• The silk solidifies when it comes in contact with the air.

• The silkworm spins approximately 1 mile of filament and completely encloses itself in a cocoon in about 2 or three days.

• The silkworm then changes into a moth. The silkworm is usually killed with heat before it reaches this stage because the moth secretes a fluid to dissolve the silk to emerge from cocoon. This damages the cocoon and the silk.

• The silk is obtained from the undamaged cocoons by brushing the cocoon to find the outside ends of the filament.

Process of obtaining fibre from cocoon

The silk filaments are then wound on a reel. One cocoon contains approximately 1,000 yards of silk filament. The silk at this stage is known as raw silk.

A yarn can now be formed by combining several filaments of silk.

Wild silk productionWild silk is obtained from cocoons that silkworms

produce in a natural uncontrolled environment. The most common type of wild silk is Tussah

Silk. Tussah silk is dark in color, coarse in texture and cannot be bleached.

Doupion is another type of wild silk. Doupioni silk is produced when two silkworms spin cocoons that are joined together.

Animal rightsAs the process of harvesting the silk from the

cocoon kills the larvae, silk-culture has been criticized in the early 21st century by animal rights activists.

Mahatma Gandhi was also critical of silk production based on the Ahimsa philosophy, i.e.,"not to hurt any living thing".

Ahimsa Silk, made from the cocoons of wild and semi-wild silk moths, is promoted in parts of Southern and North East India.

USESAbsorbent- Comfortable to wear in warm weather.Low conductivity - Keeps warm air close to skin

during cold.Elegant, soft luster and beautiful drape-

Furnishing , upholstery, wall coverings, window treatments, etc.

Clothing- Shirts, blouses, formal dresses, high fashion clothes, pyjamas, robes, sun dresses and underwear.

Parachutes, bicycle tires, comforter filling and artillery gunpowder bags.

A special manufacturing process makes it suitable as non-absorbable surgical sutures. Chinese doctors have used it to make prosthetic arteries.

Stiffened silkEmbossed

silkSinged silk

Pure dye silkBleached silkSteam fixed

silk

Enzyme finished

SILK IDENTIFICATION Non technical testsFeeling test- Smooth, soft, lustrous.Burning test- Pure silk burns slowly. Silk ash is round,

crisp, shiny, crushable black beads. Has an animal odour.

Technical testMicroscope test- Raw silk fiber from cultivated cocoon

is bave. It appears elliptical. Triangular cross section. Cultivated silk is a narrow fiber without markings. Wilk silk is coarser.

Chemical test- Concentrated cold Hydrochloric acid dissolves silk and wool fibres swell.

SILK BLENDSSilk and Cotton Soft, smooth, light weight, strength, comfort,

low cost.Silk and Linen Strength and absorbency, good hand, light

weight. Both add prestige.Silk and Wool Soft sheen, resilient, durable, good drape.

Used for suits and summer wear.

Silk+Cotton Silk +Wool

DYEING PROPERTIES Acid colors are dyed in strong acid baths

Direct colors dye silk in weak acid solutions

Basic colors may be dyed in weak acid or alkaline solutions

Vat colors are soluble only in fairly strong alkaline solutions

CARE OF SILK GARMENT Dry clean If sent to dry cleaners, inform them it’s a silk

garment. Hand washWash in cool water.Use small amount of soap or mild detergent.After washing it, rinse in cold water.Hang it or lay it flat in a shaded area to dry.If pressing is needed, use an all cotton iron board

cover, a low or moderate steam setting, and press on the wrong side of the fabric while ironing.

Other TipsTo keep white silk white, add peroxide and

ammonia to the wash. Do not use bleach or any washing detergent with

bleach To remove yellowness from white silk, add a few

teaspoons of white vinegar to the wash.

Machine wash

Dry cleanHand wash