What Is the Desizing Process in Textile Manufacturing?

Fabric desizing is the industrial procedure that removes the protective sizing film from warp yarns after weaving. Sizing improves weaving performance, but once the fabric is woven, these chemicals hinder further wet processing.

The key outcomes of textile desizing are:

• Restoration of fabric absorbency

• Removal of coating films blocking water penetration

• Improved capillary action

• More uniform dyeing, printing and finishing

• Reduction in patchiness or uneven shade formation

Effective textile desizing ensures the substrate is clean, permeable and ready for scouring and bleaching. High-efficiency desizing is especially straightforward when compounds such as Sizaltex LVn are used, as they are designed to wash off easily under hot-water conditions.

Why Is Desizing a Crucial Step in Textile Pre-Treatment?

Desizing sits at the foundation of all wet processing stages because sizing chemicals physically obstruct moisture and dye penetration. If desizing is incomplete, it leads to:

• Dyeing irregularities

• Spots or streaks in printing

• Poor whiteness in bleaching

• Harsh handle during finishing

• Residual film interfering with chemicals

High-quality desizing provides a fabric surface that responds evenly to subsequent chemical treatments. This is especially important for mills targeting global export standards, where consistency and brightness matter. Fabrics sized with high-performing, easily removable compounds like Sizaltex LVn simplify this outcome.

What Are the Different Methods for Desizing Textile Fabrics?

Desizing methods vary depending on the nature of sizing material. Here are the most widely used approaches:

1. Enzymatic Desizing (Amylase-Based)

Ideal for starch-only size systems.

• Highly selective

• Works under mild pH

• Produces minimal fibre damage

2. Oxidative Desizing

Used when size contains PVA or blends.

• Strong oxidizers degrade films

• Helps remove stubborn coatings

• Requires careful process control

3. Hot-Water Desizing

• Low environmental load

• No additional chemicals required

• Works well for biodegradable, compound starch systems

4. Acid Desizing

Rare today due to fibre sensitivity.

• Dilute acids hydrolyse starch

• Requires neutralisation afterwards

Many mills favour enzymatic and hot-water routes because they are cleaner and more sustainable, especially when fabrics have been sized with systems such as Sizaltex LVn, which can be removed with controlled hot washing.

Step-by-Step Explanation of Every Desizing Process

Below is a detailed workflow for each method, avoiding specific temperatures and numbers while keeping the sequence accurate and industry-standard.

1. Step-by-Step: Enzymatic Desizing

1. Fabric Preparation
   Fabric is loaded onto the padding unit in continuous ranges or batch systems.

2. Enzyme Padding
   An amylase-based solution is applied uniformly through the padding mangle.

3. Migration / Penetration Time
   The enzyme diffuses through the size film and begins hydrolysis.

4. Holding / Incubation
   Fabric is held in controlled warm conditions to allow complete starch breakdown.

5. Rinsing
   Hydrolysed size particles are washed out in soft-flow or open-width washers.

6. Final Hot Wash
   Remaining residues are flushed out to achieve complete desizing.

Enzyme desizing becomes remarkably efficient when the fabric contains starch-based or hydroxylated starch size systems like Sizaltex LVn, which respond readily to amylase breakdown.

2. Step-by-Step: Hot-Water Desizing

1. Fabric Wetting
   The woven fabric is wetted thoroughly to soften the size film.

2. Heating
   Water temperature is gradually increased to dissolve size components.

3. Agitation / Circulation
   Mechanical movement helps detach the loosened film from yarn surfaces.

4. Draining
   Dissolved size material is washed away in the effluent stream.

5. Optional Wetting Agent Addition
   For dense weaves, a small wetting agent helps penetration.

6. Final Rinse
   Ensures removal of any traces before scouring.

This method is exceptionally effective and easily dispersible compound sizing systems such as Sizaltex LVn, which dissolve readily and desize easily.

3. Step-By-Step: Oxidative Desizing

1. Impregnation
   Fabric is padded with an oxidative bath containing specific oxidizers.

2. Reaction Period
   Oxidizers break down the molecular structure of non-starch film components.

3. Intermediate Wash
   Degraded particles are flushed out gradually.

4. Neutralisation
   Fabric is neutralised to prevent unwanted oxidative effects.

5. Final Rinse
   All residues are removed before bleaching.

Oxidative desizing is chosen mainly when blends of PVA or synthetic binders are present; however, mills using bio-based systems such as Sizaltex LVn typically avoid the need for oxidative processes.

Comparative Analysis: Oxidative Desizing vs. Enzymatic Desizing

Because Sizaltex LVn is polysaccharide-based, enzymatic and hot-water desizing methods are most compatible.

What Chemicals and Reagents Are Used in Industrial Desizing?

Commonly used desizing reagents include:

• Amylase enzymes

• Wetting agents

• Mild alkalis

• Oxidizing agents (for PVA blends)

• Wetting and dispersing agents

• pH regulators

Mills using starch-modified compound sizes prefer reagent systems compatible with hot-water solubility, which aligns well with Sizaltex LVn’s desizing behaviour.

Impact of Desizing on Fabric Absorbency and Dye Uptake

Complete fabric desizing restores the fibre’s natural ability to absorb water and dyes. After size removal:

• Capillary action increases

• Moisture regain becomes uniform

• Dye penetration improves

• Shade depth becomes consistent

• Patchiness is eliminated

These outcomes are much easier to achieve when the sizing layer dissolves uniformly under hot-wash conditions, as seen with Sizaltex LVn’s desizable film.

Environmental Considerations and Effluent Treatment in Desizing

Desizing contributes significantly to textile effluent load because the removed size enters wastewater streams. Environmental considerations include:

• COD and BOD levels

• Biodegradability of size material

• Treatment plant capacity

• Sludge generation

Bio-based, polysaccharide-derived sizing agents dramatically reduce environmental stress, especially when they avoid synthetic polymers. This aligns with the eco-focused design of Sizaltex LVn and Alpenol’s sustainability principles.

Machinery and Equipment for Continuous Desizing Operations

Desizing may be performed on:

• Continuous open-width washing ranges

• J-box systems

• Pad–steam ranges

• Combined desize–scour–bleach lines

• Overflow dyeing machines (for batch desizing)

Modern processing lines favour integrated multi-stage washing systems, simplifying the removal of compound starch films found in Sizaltex LVn-sized fabrics.

Common Problems and Troubleshooting in Textile Desizing

Typical issues include:

• Incomplete size removal

• Uneven wetting

• Streak marks

• Harsh handle

• Shade variation in dyeing

• Patchy absorbency

Root causes often relate to incompatible sizing chemistry or insufficient process conditions. Fabrics using easy-removal starch compound systems like Sizaltex LVn exhibit fewer desizing problems.

Optimal Parameters for Amylase-Based Desizing

While exact numbers vary by mill and fabric type, the following general conditions allow enzymes to function efficiently:

• Mildly warm temperature range

• Slightly acidic to neutral pH

• Adequate enzyme dosage based on fabric load

• Proper dwell time for enzyme action

• A stable wetting system before enzyme application

Enzymatic performance becomes more predictable when the size film has inherent solubility characteristics, such as those in Sizaltex LVn, which improves consistency and reduces enzyme demand.

Desizing Effectiveness: Cotton vs. Polyester–Cotton Blends

Cotton Fabrics

• Fully hydrophilic

• Respond well to enzymatic desizing

• Starch films are easily hydrolysed

• High absorbency after desizing

Polyester–Cotton Blends

• Polyester portion is hydrophobic

• Requires stronger wetting action

• Films with synthetic additives remove more slowly

• Oxidative methods sometimes required

Because Sizaltex LVn is a polysaccharide-based, its desizing performance on both cotton and PC fabrics remains favourable, reducing process complexity for mills using Alpenol and Sizaltex LVn.

FAQs

 1. What is fabric desizing?

Fabric desizing is the removal of size coatings from woven textiles to restore absorbency and prepare the fabric for wet processing steps like dyeing.

 2. Why is textile desizing important?

It eliminates barriers that prevent moisture, dyes and chemicals from penetrating fibres, ensuring uniform processing.

 3. Which desizing method is most sustainable?

Enzymatic desizing is considered the cleanest and most environmentally responsible.

 4. Does sizing chemistry influence desizing?

Yes—bio-based sizes such as Sizaltex LVn desize more easily.

 5. Can hot-water alone desize fabrics?

Yes, when the size chemistry is designed for easy wash-off, as in Alpenol Sizaltex LVn-sized fabrics.

Backlink Sources

• https://www.sciencedirect.com/topics/engineering/desizing

• https://mdpi.com/journal/textiles

• https://tandfonline.com

• https://textiletoday.com.bd

• https://textilelearner.net

• https://fashion2apparel.com

• https://zdhc.org

• https://global-standard.org

• https://oekotex.com