This presentation discusses pretreatment processes like scouring and bleaching. Scouring removes impurities from textiles using alkali to increase absorbency. The standard scouring recipe uses sodium hydroxide, soda ash, and wetting agents. Bleaching destroys color from fabrics using oxidizing agents to break color linkages. The standard bleaching recipe uses hydrogen peroxide, sodium silicate, and wetting agents. The presentation suggests future pretreatment methods may use eco-friendly enzymes instead of chemicals and integrate processes into single machines.

1. Presentation on
PRETREATMENT (SCOURING & BLEACHING)

2. PRESENTED
By
Name: Shawan Roy
ID: 11122107023
Intake: 5th
Section: 01
B.Sc. In Textile Engineering, BUBT
To
Md. Mahabub Hasan
Lecturer,
Department of Textile Engineering,
BUBT

3. CHAPTER
• What is pretreatment?
• Types of Pretreatment Process.
• What is Scouring?
• Objective of Scouring.
• Recipe of Scouring.
• Future of Scouring.
• What is Bleaching?
• Objective of Bleaching.
• Recipe of Bleaching.
• Future of Bleaching.
• Conclusion

4. PRETREATMENT
• Pretreatment means treatment
the fabric, yarn or fiber before
dyeing.
• Pretreatment processes include
desizing, scouring, and bleaching
which make subsequent dyeing
and softening processes easy.

5. TYPES OF PRETREATMENT PROCESS
• There are various types of
pretreatment process.
• Singeing
• Desizing
• Scouring
• Bleaching
• Mercerizing etc.

6. SCOURING
• The term scouring applies to the
removal of impurities such as oil,
wax gum, soluble impurities and
solid dirt commonly found in
textile material.
• The process consists essentially of
treatment with alkali, a good
supply of water is essential.

7. OBJECTIVE OF SCOURING
• To remove natural as well as
added impurities of essentially
hydrophobic character as
completely as possible.
• To increase absorbency of textile
materials.
• To leave the fabric in a highly
hydrophilic condition without
undergoing physical or chemical
treatment or damage.

8. RECIPE OF SCOURING
• Sodium Hadroxyde = 4gm/l
• Soda ash = 2gm/l
• Wetting Agent = 1cc/l
• Sequestering Agent = 1cc/l
• Detergent = 1gm/l
• Time = 30min
• Temperature = 95°C
• pH = 10.5 - 11
• M:L = 1:10

9. FUTURE OF SCOURING
• EcoScour or Bio-scouring is
possible in future scouring
process.
• Features:
– No caustic soda
– Neutral pH scouring process
– Combined scouring and bio-finishing
• Benefits
– Up to 31% shorter process
– Softer fabrics
– Enhanced absorbency/dye uptake
– Reduced fabric weight loss

10. BLEACHING
• The process of destroying natural
color from fabric is called
bleaching
• This bleaching done by destroying
the chromophore linkage from
fabric.
• Oxidizing or reducing agent must
be needed to break the
chromophore linkage

11. OBJECTIVE OF BLEACHING
• To produce white fabric by destroying
coloring matter with minimum fiber
degradation.
• Further improvement of whiteness by
treatment with optical whiteness agents.
• Removal of colored impurities.
• Removal of the seed coats.
• Minimum tendering of fiber.
• Technically reliable & simple mode of
operation.
• Low chemical & energy consumption.
• Increasing the degree of whiteness.

12. RECIPE OF BLEACHING
• Hydrogen peroxide = 5gm/l
• Sodium Silicate = 2.5gm/l
• Wetting Agent = 1cc/l
• Sequestering Agent = 1cc/l
• Detergent = 1gm/l
• Time = 30min
• Temperature = 95°C
• pH = 10.5 - 11
• M:L = 1:10

13. FUTURE OF BLEACHING
• Enzymatic bleaching is the advance
type of bleaching which is used in
future.
• Features:
– No Hydrogen peroxide
– Neutral pH bleaching process
– Enzyme should be automatically destroy.
• Benefits
– Up to 25% shorter process
– Enhanced brightness or whiteness of
fabric
– Increase the reflection of whitness.

14. CONCLUSION
• Now a days scouring and bleaching must be done in same
machine with combined recipe.
• Souring and bleaching are must be needed for white fabric.
• For dark shade of dyeing we can reduce our cost by removing
any of this process.
• But in light shade those two process must be needed.
• In future, we can imagine that the all pretreatment section are
must be done in one machine.