This document discusses various methods for desizing fabric after weaving to remove starch paste. It describes the objectives of desizing as removing starch paste to increase fabric absorbency, affinity for dry chemicals, and suitability for downstream processes. The key desizing methods discussed are rot steeping, acidic desizing using hydrochloric or sulfuric acid, alkaline desizing using caustic soda, enzymatic desizing using amylase enzymes, and oxidative desizing using chlorine or bromine. Each method is explained in terms of its process, advantages, and disadvantages. Enzymatic desizing is noted as requiring less time and avoiding fibre damage compared to other methods. Proper control of temperature, pH, and time is important for

1. Shree guru gobind singhji institute of
engineering and technology
DEPARTMENT OF TEXTILE TECHNOLOGY

2. Desizing
 INTRODUCTION:- Removal of size paste/ starch after weaving from the fabric. Fabric becomes free from the size paste by this .
 CLASSIFICATION OF METHODS FOR DESIZING:-
1.HYDROLYTIC :- 2. OXYIDATIVE:-
Rot steeping
Alkaline Chlorite
Acid desizing Bromite
Enzymatic desizing

3. Objectives of desizing
 To remove starch paste from fabric
 To increase the absorbency power of fabric
 To increase affinity of fabric to dry chemicals.
 To make fabric suitable for next process.’
 To increase the lustre of fabric and dyeing and printing.

4. Rot steeping desizing.
 advantages :-
1. Cheapest method compare to other.
2. No chemicals are required.
Disadvantages:-
1. Requires more space.
2. It is slow process, so desizing time is long
3. Mildew may attack the cloth during steeping.
4. And cause scales on fabric.

5. ACIDIC desizing

6.  Process –
1. Hydrochloric acid or dilute supjhuric acid used to hydrolyse the starch from fabric.
2. 0.25% -0.5% solution of acid at room temperature is suitable for this process.
3. The cloth is impregnated with diluteacid soln. in a bowl for 8 – 12 hours in a closed concrete pit.

7.  Advantages-
1. It is economical process.
2. This process is effective and give fairly uniform desizing.
3. This process is qquicker than rot steeping.
 Disadvantages-
1. The mineral acid which harmful to cellulose fibres if proper care is not taken.
2. Especially during storage stage, acid- wet fabric must not allowed to dry.
3. This would cause formation of hydrocellulose ,which will weaken the fibre,

8. ALKALI DESIZING
 REQUIREMENT :-
2-3 %CAUSTIC SODA
3-4 HOURS
60 DEGREE CEL.
 WORKING TRAIT :-MECHANISM

9. Enzymatic desizing
 What is enzyamatic desizing ?
--- its main intension is to remove starch from fabric. Contain amylase.
 How does amylase works on starch?
1. effect of inadequate desizing .
2. checking effectiveness of desizing
3. some typical size may not be affected by enzyme action i.e. tapiaco starch.

10. enzymes
 What Is enzyme ?
Types of enzyme:-
a substance produced by a living organism which acts as a catalyst to bring
about a specific biochemical reaction.
Vegetable Distase
Bacteria Rapidase
animal Amylase
Desizing enzymes are:
Animal origin: Viveral, Degomma, waste pancrease,
cotted blood, liver etc.
Vegetable origin:
i, biolase, Taka etc.

11. Condition for enzymatic desizing:-
Enzyme Concentr
ate g/L
Temperat
ure (ºC)
pH
Pancreati
c (animal)
1-3 50-60 6-7.5
Malt
extract
3-18 50-60 6-7.5
Bacterial 0.5-1 60-70 5.5-7.5

12. Advantages :-
 Time require for enzymatic desizing is less.
 No fibre damage occur.
 It is continuous process so greater production is possible by this.
 There is no chance for cellulose to hydrolysed like acid desizing.
Disadvantages:-
 If condition like temperature ,pH, time not maintained properly the desizing activity of enzyme
is destroyed.

13. Oxidation desizing
 Chlorine desizing :-
1. how desizing is possible?
2. safetry regarding chlorine desizing .
 Bromine desizing:- powerful action like
- 1. chlorine method free, nacent oxygen removes size.
2. oxygen breaks stable starch bonds.

14. Thank you
PRESENTED BY :-
1. VARAD WAGH
2. AJINKYA MULE
3. PRASHANT JADHAV
4. PRASAD SWAMI
5. GAURAV GODARE
GUIDED BY – MR. KAR