Pretreatment processes like singeing, desizing, scouring, and bleaching prepare textiles for dyeing by removing sizes, oils, and impurities. Faulty pretreatment can cause uneven dyeing. Other causes of dyeing faults include hard water, improper dye or chemical amounts, uneven agitation, and machine issues. To prevent faults, pretreatment and dyeing processes must be carefully controlled, and machines and water sources properly maintained.

1. PRESENTED BY :-
PRESENTATION ON DYEING FAULT DUE TO FAULTY
PRETREATMENT
PRESENTATION ON DYEING FAULT DUE TO FAULTY
PRETREATMENT

2. What is pretreatment?
The process which is done to make the textile materials
suitable for dyeing and printing. Such as singeing,
desizing, scouring, bleaching etc.

3. PROCESS OF PRETREATMENT
All the processes of this stream are carried out in an
aqueous state or aqueous medium. The main processes
of this section include :
• singeing
• Desizing
• Scouring
• Bleaching
• Mercerizing

4. Singeing:
• Singeing is an important part
of pretreatment. This is the burning off
of protruding fiber ends from the
surface of the fabric.

5. OBJECTIVES OF SINGEING
• Singed fabrics allow printing of fine intricate patterns
with high clarity and detail.
• Singed fabrics allow printing of fine intricate patterns
with high clarity and detail.

6. SIZING
• In sizing starch is applied to the yarn to make the yarn
suitable for next process

7. Objective of sizing
• To make a weavers beam with the exact number of
warp threads ready for weaving
• To increase the strength of the spun warp yarn without
affecting its extensibility.

8. Desizing:
• Desizing is the process or removing the
starch or size the covering the warp
yarn using enzyme. Oxidizing agent, or
other chemicals

9. Objectives Of Desizing:
• To eliminate the water repellent nature of si
zed cloth.
• To increase the absorbency.
• To reduce the consumption of chemicals in s
ubsequent process.

10. Scouring:
• Scouring is the process by which all
natural and additive impurities such as
oil, wax, fat, hand dust etc. are
removed to produce hydrophilic and
clean textile material. It is one of the
vital processes of wet processing.

11. Objects of Scouring:
To make the fabric highly hydrophilic.
To remove impurities such as oils,
waxes, gum, husks as nearly as
possible.
To increase absorbency of fabric or
textile materials without physical and
chemical damage.

12. Bleaching:
• Bleaching is chemical treatment
employed for the removal of natural
coloring matter from the substrate.
The material appears whiter after the
bleaching

13. Mercerizing:
• Mercerization is one of the most
important finishing processes of cotton
with a strong caustic alkaline solution
in order to improve the lustre, hand
and other properties. It imports gloss
to the fiber, increases its
hygroscopicity, strength and improves
its dye affinity.

14. Difference between mercerized and un-
mercerized fabric after dyeing

15. The faults which are visible after dyeing are called Dyeing faults . These
faults describes the quality of the fabrics . So to overcome from this faults
we have to know the causes and the remedies of these dyeing faults .

16. Causes Of Dyeing Defects
 Due to Material:
– Material having dead fibers or other defective fibers.
– Left over of Chemicals after scouring, bleaching etc.
– Material not properly singed, desized.
– Material not properly mercerized.
– Absorbency of the fabric not proper.
– Sticking of insoluble material on the fibers.
– Impurities are not removed properly.
– Uneven heat treatment.

17. Causes Of Dyeing Defects
 Due to Water Quality:
– More Hardness of water
– Water has metal ions such as iron.
– pH of water not proper
– Water having more chlorine
 Due to Improper Dye Solution:
– Improper weight ratio of colors, material and chemicals.
– Improper material to water ratio
– Improper filtering of concentrated colors.

18. Faults in Dyeing SectorFaults in Dyeing Sector

20. Causes:
1. Dye bath water hardness.
2. Deposition of ferrous or ferric ion on the fabric
surface
3. Defective plaiting device of the machine.
Remedies:
Check presence of any sharp object in
machine
Provide magnetic filters in water/ steam
line

21. Causes:
I.Change in pick-up percentage along the length of the
fabric .
II.Improper fabric Speed.
III.Machine over-loading.
IV.Running at lower nozzle pressure .
V.High bath draining temperature .
VI.Improper cycle time .
VII.Improper length of rope .

22. Causes:
i.Operator negligence
ii.Dye bath hardness
iii.Improper Agitation of dyestuff
iv.Dye molecule deposition on the fabric
Remedies:
Use adequate amount sequestrate to lower bath
hardness.
Proper agitation

23. Causes:
i)If uneven pretreatment is done, absorbency
and whiteness of fabric will be different at
different places and consequently uneven
dyeing will occurred.
ii) Very rapid addition of dyes and chemicals.
Remedy:
• By ensuring even pretreatment.
• Proper dosing of dyes and chemicals.

24. Sources & Causes:
1.Fluctuation of Temperature.
2.Improper dosing time of dyes & chemicals.
3.Batch to batch weight variation of dyes and chemicals.
4.Dyes lot variation.
5.Improper reel speed, pump speed, liquor ratio.
6.Improper pretreatment.

25. Remedies:
Use standard dyes and chemicals.
Maintain the same liquor ratio.
Follow the standard pretreatment procedure.
Maintain the same dyeing cycle.
Identical dyeing procedure should be followed for the same depth
of the Shade.

26. Sources & Causes:
I. Improper dyes solubility.
II. Hardness of water.
III. Faulty m/c speed, etc.
IV. Poor
V. migration property of dyes.
Remedies:
• Use standard dyes and chemicals.
• Proper m/c speed.

27. Sources & Causes:
1. Poor opening of the fabric rope
2.Shock cooling of synthetic material
3.If pump pressure & reel speed is not equal
4.Due to high speed m/c running
Remedy:
Anti- creasing agents are used to avoid crease
mark problem.
Maintaining proper reel sped & pump speed.
Lower rate rising and cooling the temperature
Reducing the m/c load
Higher liquor ratio

28. Sources & Causes:
I.More oil & grease use the wheel, roller bearing into place.
II.To stay unclean the m/c.
III.Be decay the roller.
IV.Fabric waste.
REMEDIES:-
Use a oil which has high viscosity.