The document discusses dyeing processes for textiles. It defines dyeing as changing a textile's physical or chemical properties to make it uniformly colored. The objectives of dyeing are to increase attractiveness, make fabrics suitable for various uses and decorative purposes. The dyeing process involves 4 steps - dye molecules attaching to and migrating within fiber molecules through hydrogen bonding. Common dye types include acid, basic, direct, disperse, sulfur, mordant, reactive, and vat dyes. Dyeing machines include open and enclosed types, and types where materials, liquor, or both circulate. Common dyeing faults result from uneven processes, improper temperatures/times, and machine issues.

1. SHYAMOLI TEXTILE ENGINEERING COLLEGE

3. Contents:
 Defination
 Objectives
 Theory of dyeing
 Various types of dyes
 Flow chart of Dyeing process
 Dyeing machines
 Dyeing faults
 Causes of Dyeing defeats

4. DYEING:
 The process by which a textile material is to be
changed physically or chemically , so that it
looks mono uniform colored is called dyeing.

5. Objectives of Dyeing:
 To increase the attractiveness of the
textile goods.
 To make the fabric suitable for
various usage.
 To make the textile goods suitable for
decorative purposes.

6. The whole process of dyeing is completed
by 4 steps:
1) Dye molecules comes to the fabric surface
from the dye bath.
2) Fiber absorbs the dye molecule from the
outer surface of the fiber to the internal
surface of the cellulose.
3) Migrates the dye molecules everywhere of
the fiber molecules.
4) Fixing the dye molecules to the fiber
molecules by hydrogen bond.

7. Flow chart of Dyeing
process:
Grey textile material
Singeing
Desizing
Scouring
Bleaching
Mercerizing
Dyeing/Printing
Finishing
Marketing

8. Various classes and types of
dyes :
 Acid Dyes
 Basic (Cationic) Dyes
 Synthetic Dyes
 Direct Dyes
 Disperse Dyes
 Sulfur Dyes
 Mordant Dyes
 Reactive Dyes
 Metalized Dyes
 Gel Dyeing
 Developed Dyes
 Azo Dyes
 Aniline Dyes
 Vat Dyes

9.  Acid dyes are water-soluble anionic dyes that
are applied to fibers such as silk, wool, nylon.
 Basic dyes are water-soluble cationic dyes
that are mainly applied to acrylic fibers.
 Direct dyeing is done in a neutral or
slightly alkaline dye bath with the addition
of sodium chloride (NaCl) or sodium
carbonate(Na2CO3). It is used on cotton,
paper, leather, wool, silk and nylon.

10.  Azoic dyeing is a technique in which an
insoluble Azo dye is produced directly onto
or within the fiber.
 Sulfur dyes are inexpensive dyes used to dye
cotton with dark colors. Dyeing is effected by
heating the fabric in a solution of an organic
compound.
 Vat dyes are essentially insoluble in water and
incapable of dyeing fibers directly.

11.  Mordant dyes require a mordant, which
improves the fastness of the dye against
water, light and perspiration.
 Reactive dyes utilize a chromophore attached
to a substituent that is capable of
directly reacting with the fiber substrate.

12. Dyeing Machine:
According to dyeing process:
1) Open dyeing machine
2) Enclosed dyeing machine
According to material and liquor movement:
1) Material move but liquor does not circulate i.e; jigger
2)Liquor circulate but materials does not move i.e; all package dyeing
machine.
3)Both materials and liquor circulate i.e; jet dyeing machine

13. Knit dyeing by jet dyeing machine
Knit dyeing :

14. Sequence of Operation for Knit Fabric Dyeing:
Grey fabric inspection
↓
Batching
↓
Fabric turning
↓
Loading to the m/c
↓
Pre-treatment (Scouring & Bleaching)
↓
Dyeing
↓
Dewatering
↓
Drying
↓
Compacting & Calendaring
↓
Final inspection & packing

15. Faults of Dyeing:
 Uneven Dyeing
 Batch to Batch Shade variation
 Patchy dyeing effect
 Roll to roll variation or Meter to Meter variation
 Crease mark
 Dye spot
 Wrinkle mark
 Softener Mark

16. Dyeing Faults
Major dyeing faults which occur during are mentioned below:
 Uneven Dyeing:
Due to uneven scouring and uneven bleaching.
Lack of control dyeing machine.
 Batch to Batch Shade variation
Improper Temperature.
Improper time of dyes & chemicals.
 Patchy dyeing effect
Faulty injection of alkali.
Improper addition of color.
Due to hardness of water.

17.  Crease mark:
Poor opening of the fabric rope
If pump pressure & reel speed is not equal
Due to high speed m/c running
 Dye spot:
Improper Dissolving of dye particle in bath.
Improper Dissolving of caustic soda particle in
bath.