Dyeing is the process of coloring fibers, yarns or fabrics using chemicals. Different types of dyes are used for different dyeing processes and for cotton dyeing specifically. Reactive, vat, sulphur, azoic, basic, and natural dyes can be used. Reactive dyes must be anionic, soluble, lightfast, washfast and fix under alkaline conditions. Azoic dyes must be soluble but produce insoluble color, have excellent lightfastness and increased rubfastness. Sulphur dyes must produce sulphur linkages, be insoluble in water but soluble when mixed with reducing agents under alkaline conditions. Dyeing requires additional chemicals like solubilizing

2. Dyeing:
Dyeing is the process of coloring
fibre, yarn or fabric by using different
types of chemicals.
Mostly different types of dyes are
used for different dyeing processes.

3. Cotton Dyeing
Different Types of dyes are used for cotton dyeing.
Reactive Dyes
Vat Dyes
Sulphur Dyes
Azoic Dyes
Basic Dyes
Natural Dyes
All Purpose Dyes

4. Required Properties for
Reactive Dye
 Must be anionic to attract cellulose
 Need to have good solubility
 Must have good light fastness
 Must have good wash fastness
 Fixation must be done under alkaline condition
 Need to have less time requirement
 This dye is cheap and available

5. Required Properties of Azoic Dyes
 Die will be soluble but final color will be insoluble
 Have to have excellent light fastness
 Rub fastness should be increased as much can.
 Less binding effect should be created by Azo dye
 Temperature should keep <10 degree Celsius
during dyeing.

6. Required Properties of Sulphur Dyes
 Must produce sulphur linkage with fibre
 Need to be insoluble in water
 Reducing agent requirement should be good
 Must mix with reducing agent properly to be
soluble
 Dyeing is done under high alkaline condition
 Shade & wash fastness should be good.

7. Other chemicals used for dyeing
process of cotton:
• Solublizing Agent
• Reduction Agent
• Alkali
• Binding Agent
• Wetting Agent
• Antifoaming Agent
• Anti-migrating Agent
• Electrolyte

8. Requirements of the dye auxelariex
Solublizing Agent
Increase the solubility of dyes
Controls the sublimation at high temperature
Reduction Inhibitor
Mild oxidizing agent controls the reduction of dyes
at high temperature or during steaming.
Binding Agent
Use as an adhesive to fix the pigment dyes on
cotton fiber at high temperature.

9. Requirements of the dye auxelariex
Alkali
Caustic:
Controls the rate of reaction between
dyes and cellulose or in other words it is used
for fixation of Reactive Dyes.
Soda Ash:
Controls the rate of reaction between dyes
and cellulose or in other words it is used for
fixation of Reactive Dyes.
Increases the fastness properties during
washing

10. Antifoaming Agent
Used to prevent formation of foam during
stirring or during dyeing in one bath.
Anti-migrating Agent
Increases the viscosity of dyeing liquor to protect
migration of dyes under high temperature.
Electrolyte
Decreases solubility of dyes in liquor
Increases affinity between dyes and fiber under
moist condition

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