Degumming

100% Silk Fibers

1. Degumming (to get rid of non-fibrous materials (sericin))

2. Bleaching (to make the goods whiter)

Carbonising

• 100% Wool Fibers

• 1. Carbonising (to remove leave, bark and other parts of the plants from the wool fibers)

• 2. Scouring (to get rid of fat and oil from the fibers)

• 3. Bleaching (to make the fibers whiter)

• Morphology of Textile Fibers• 1. Crystalline Regions are the regions that cannot

absorb water, humidity and dyestuff solutions but they are the part for fiber strength.

• 2. Non-Crystalline Regions or Amorphous regions are the regions that can absorb water, humidity and dyestuff therefore they can be dyed but they are a very weak part of the fibers.

3. Orientation of the Crystalline Regions alongside the fiber axis

This property is very important in that it will increase the tensile strength of the fiber i

f it presents in the optimal quantity.

Introduction• The outer hydrophobic layer has to be removed to make the fabric

absorbent

• The process by which the water-resistant layer is removed is called ‘scouring’

• In cotton textile processing, scouring is also known as kiering, kier-boiling or boiling out– Boiling the cloth or yarn in alkaline chemicals– The boiler or vessel in which this is done is called a “kier” and hence

the terms “kiering” and “kier-boiling”

• Changes taking place during “Scouring”

– The saponifiable oils in it are converted into soaps

– The unsaponifiable oils and waxes it contains are emulsified

– The proteins are hydrolysed into soluble products

– The pectose and pectins are changed into soluble salts of pectic or metapectic acids

– Mineral matter is dissolved– Dirt particles are removed and held in a stable form in the kier liquor

• Saponification

– Vegetable oils, animal fats and mineral oils are not soluble in water

– A vegetable oil is a glyceride of fatty acid

– When oil such as this is heated with a solution of NaOH in water• Oil splits up into fatty acid and glycerine• Glycerine dissolves freely in water• Fatty acid reacts with NaOH to form its sodium salt i.e. soap which

is also soluble in water

– The conversion of glycerides of fatty acids into soaps by using NaOH is known as “saponification”

• Emulsification

– Waxes present in the fibre cannot be removed by saponification

– They can however be removed from the fibre by converting them into emulsion, which can be held into kier solution

– An emulsion is a fairly stable mixture of two liquids, which normally do not mix with each other

– The soap formed by the saponification of oils in the kier acts as the emulsifying agent

Waxes + Soap Emulsion (already formed by a saponification or added)

Solvent ScouringSolvent Scouring• Scouring is done with trichloroethylene

• The fabric is impregnated and passed through trichloroethylene where the wax and oil dissolves and are removed

• Other impurities that remain will be degraded and dissolved during ‘peroxide bleaching’

• Satisfactory in conjunction with peroxide bleaching

Standard Recipe for scouring• Standard Recipe: The amount of different chemicals used in a kier boiler

may vary according to – Hardness of water.– Quality / Quantity of cotton.– Fabric construction/ texture, yarn twist etc.– But in generally, the following amounts of the chemical are used.

• Caustic Soda (Strong)→ 2-5% owf• Soda ash (mild)→ 0.3-0.5%• Sequestering agent→0.05-0.5%• Wetting agent→ 0.25-1.0%• M:L→1:4 to1:5• Temp→100˚C-120˚C• Time→12hrs - 4hrs