Problems, Causes and Remedies in Enzymatic Desizing

Last Updated on 11/03/2025

What is Enzymatic Desizing?

Enzymatic desizing is the process of degrading starch size on cotton fabrics using enzymes. It is an eco-friendly process used to remove starch-based sizing agents from fabrics. Enzymes are complex organic, soluble biocatalysts formed by living organisms that catalyze chemical reaction in biological processes. They are quite specific in their action on a particular substance. Enzymes have high molecular weights. A small quantity of enzyme is able to decompose a large quantity of the substance it acts upon. Enzymes are usually named by the kind of substance degraded in the reaction it catalyzes. Enzymes can originate from animal or vegetable sources. Amylases are the enzymes that hydrolyze and reduce the molecular weight of amylose and amylopectin molecules in starch, rendering it water soluble enough to be washed off the fabric. Amylase enzymes are highly effective catalysts for the hydrolysis of the amylose and amylopectin components of the starch. Effective enzymatic desizing requires strict control of pH, temperature, water hardness, electrolyte addition and choice of surfactant. Normal types are applied for several hours at 65–70°C.

The purpose of desizing process is to remove sizes that have been attached to warp yarns during a weaving process for better weavability. The earlier methods of the desizing involved the treatment of the textile materials using severe and harsh oxidative chemicals like hypochlorites, peroxides and chlorites or treating the fabric with very dilute solutions of mineral acids for a very long time. Both the methods, often, resulted in the damaging the substrate when the attempts were made to remove the sizing ingredients to a higher level. To overcome this problem enzymatic desizing is done. The main advantage of enzymatic desizing is that it is gentle and mild treatment, hence no adverse effect on cotton or polyester.

Types of Desizing Methods:

Different methods of desizing are: A desizing method is selected on the basis of analysis of size, type of fabric, eco friendliness, ease of removal, and cost of desizing and effluent treatment.

Different methods of desizing are:

1. Enzymatic desizing
2. Oxidative desizing
3. Acid steeping
4. Rot steeping
5. Desizing with hot caustic soda treatment, and
6. Hot washing with detergents

The most commonly used methods for cotton are enzymatic desizing. This desizing process consists of three main steps: application of the enzyme, digestion of the starch and removal of the digestion products. The common components of an enzymatic desizing bath are as follows:

• Amylase enzyme
• pH stabilizer
• Chelating agent
• Salt
• Surfactant, and
• Optical brightener

Common Problems / Causes and Remedies in Enzymatic Desizing

Though enzymatic desizing process is most popular and effective but it has some problems. The main problems / defects of enzymatic desizing process are point out below.

1. Incomplete desizing
2. Fabric Damage (Strength Loss)
3. Uneven desizing (width ways)
4. Uneven desizing (lengthways)
5. Uneven desizing (random)
6. Poor Removal of Sizing Residues

Causes and remedies of these problems are discussed following:

A. Incomplete Desizing

Residual starch remains on the fabric, leading to uneven dyeing, printing defects, or poor absorbency.

Causes:

1. Inadequate enzyme
2. Inappropriate desizing bath pH
3. Inappropriate desizing-bath temperature
4. Insufficient fabric pick-up
5. Insufficient digestion time
6. Poor enzyme activity
7. Deactivation of enzyme due to presence of metals or their contaminants
8. Ineffective wetting agent
9. Incompatible wetting agent

Remedies:

1. Sufficient enzyme
2. Optimum pH
3. Optimum temperature
4. Optimum squeeze pressure and use of wetting agent
5. Optimum digestion time
6. Use of good enzymes
7. Use of soft water and Use of appropriate sequestering agents
8. Use of good and effective agent
9. Use of compatible wetting Agent

B. Fabric Damage (Strength Loss)

Some enzymes may attack cellulosic fibers (e.g., cotton). Weakness, pilling, or fiber degradation in the fabric.

Causes:

1. Overuse of enzyme or excessive reaction time.
2. High mechanical agitation.
3. Incorrect pH or temperature leading to fiber degradation.

You may also like: Application of Enzymes in Textile Processing

Remedies:

1. Use the recommended enzyme concentration and time.
2. Reduce mechanical action during washing.
3. Maintain controlled temperature and pH within safe limits.

C. Uneven Desizing (width ways)

Causes:

1. Uneven pad pressure [across the width]
2. Non-uniform pad temperature
3. Non-uniform chemical concentration in the bath

Remedies:

1. Uniform squeeze pressure
2. Uniform bath temperature
3. Uniform chemical concentration

D. Uneven Desizing (lengthways)

Causes:

1. Uneven pick-up (along the length)]
2. Preferential drying of outer layers of the batch
3. Temperature variation during digestion

Remedies:

1. Uniform pick-up along the fabric length
2. Covering the batch with polythene or other suitable sheet and keeping the batch rolling
3. Covering the batch with polythene or other suitable sheet and keeping the batch rolling

E. Uneven Desizing (random)

Causes:

1. Poor wetting agent
2. Inappropriate bath temperature
3. Foaming in the bath
4. Improper use of defoamer
5. Uneven liquor distribution during padding
6. Non-uniform washing after desizing

Remedies:

1. Use of effective and compatible wetting agent
2. Optimum bath temperature
3. Use of appropriate defoamers
4. Use of appropriate defoamers
5. Uniform liquor distribution during padding
6. Thorough and uniform washing after desizing

F. Poor Removal of Sizing Residues

Enzymes remain active on the fabric, causing unintended fiber breakdown.

Causes:

1. Incomplete enzymatic breakdown of starch.
2. Improper washing after desizing.
3. Presence of synthetic sizing agents not affected by enzymes.

Remedies:

1. Ensure sufficient enzyme activity by maintaining optimal conditions.
2. Use hot water washing (80-90°C) to remove degraded starch completely.
3. If synthetic sizes are present, use a combination of oxidative or alkali desizing.

Conclusion

Enzymatic desizing is an effective and sustainable technique for removing sizing agents from textiles. However, several issues such as incomplete desizing, fabric damage, uneven desizing, poor residue removal, and enzyme inactivation can arise due to improper process conditions. Achieving optimal results requires careful attention to process parameters such as enzyme concentration, pH, temperature, and contamination control.

References

Mazharul Islam Kiron

Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.

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