What Is Sizing in Textile Manufacturing?

Definition

Sizing is the process of applying a protective film (called the sizing solution) to warp yarns before weaving.

Purpose of Sizing

• Increase tensile strength

• Reduce hairiness

• Improve abrasion resistance

• Control yarn friction

• Enhance weaving efficiency

During the weaving process, warp yarns face constant friction from:

• Heald wires

• Reed dents

• Drop pins

• High-speed air-jet insertion

Sizing strengthens the warp thread so it can survive these mechanical stresses.

How Do You Know Sizing Is Done Optimally?

Optimal sizing is measurable. It is not guesswork.

Key Quality Control Parameters

Practical QC Tests

1. Size Add-On Test

Measures weight difference before and after sizing.

2. Moisture Test (Pleva System)

Online moisture monitoring ensures yarn is not over-dried.

3. Strength Testing

Single-end tensile testing confirms strength gain.

4. Visual Film Inspection

Checks for uniform coating and absence of patches.

Stable compound sizing systems help maintain consistent pick-up and adhesion .

What Are the Characteristics of an Optimally Sized Yarn?

An optimally sized warp yarn should have:

1. Uniform Film Formation

Even coating across the entire yarn length.

2. Reduced Hairiness

Fibers are bonded to the yarn body.

3. Improved Abrasion Resistance

Minimal fluff formation during rubbing.

4. Balanced Flexibility

Not too stiff (brittle), not too soft (sticky).

5. Controlled Diameter

Excessive add-on increases yarn thickness and affects fabric cover factor.

Hydroxylated starch-based compounds enhance bonding through additional hydroxyl functionality, improving film adhesion without excessive thickness .

Common Sizing Defects and How to Detect Them

1. Over-Sizing

Symptoms:

• Sticky yarn

• High loom friction

• Increased warp breaks

Detection:

• Excess size add-on %

• High fabric stiffness

2. Under-Sizing

Symptoms:

• High hairiness

• Frequent warp breakage

• Poor abrasion resistance

Detection:

• Low tensile strength gain

• Visible fiber protrusion

3. Uneven Size Pick-Up

Symptoms:

• Shade variation in dyed fabric

• Uneven weaving performance

Detection:

• Variable weight across warp sheet

• Moisture inconsistency

4. Brittleness (Over-Drying)

Symptoms:

• Warp snapping

• Reduced elongation

Detection:

• Low residual moisture

• High stiffness

Maintaining recommended temperature in the sizebox (typically 85–90°C depending on the sizing system) ensures proper penetration and stability .

Why Do Sizing Inconsistencies Happen?

Sizing inconsistencies arise from mechanical, chemical, or operational variations.

Mechanical Causes

• Uneven squeeze roll pressure

• Improper warp tension

• Temperature fluctuations in drying cylinders

Chemical Causes

• Incorrect cooking procedure

• Poor viscosity control

• Improper formulation balance

Advanced cooking systems using high-pressure autoclave techniques improve starch activation and stability .

Operational Causes

• Inadequate operator training

• Poor monitoring

• Irregular maintenance

How Can Quality Control Prevent Sizing Defects?

Preventive QC Measures

1. Viscosity Monitoring

Maintains proper flow and penetration.

2. Temperature Control

Stable cooking and sizebox temperature.

3. Moisture Regulation

Prevents brittleness or softness.

4. Pick-Up Calibration

Squeeze roll pressure calibration ensures uniform add-on.

5. Routine Yarn Testing

Regular tensile and abrasion testing.

How Sizing Chemicals Play a Role in Maintaining Quality

The formulation of sizing chemicals directly influences quality control stability.

Key Chemical Attributes for QC Stability

Modern compound sizing agents are engineered to:

• Reduce synthetic dependency

• Maintain film flexibility

• Support high-speed weaving

Sustainability-focused systems eliminate unnecessary synthetic binders while maintaining performance .

Quality Control Checklist for Textile Sizing

1. Check viscosity every batch

2. Monitor size add-on percentage

3. Maintain sizebox temperature

4. Measure residual moisture

5. Test yarn tensile strength

6. Inspect film uniformity

7. Track loom efficiency

How Quality Control in Sizing Impacts Weaving Performance

Proper QC results in:

• Lower warp breakage rate

• Higher loom efficiency

• Consistent woven fabric density

• Improved fabric quality

Sizing directly impacts:

• Shedding smoothness

• Reed beating stability

• Weft insertion reliability

Without QC, even high-quality yarn cannot perform efficiently in weaving.

FAQs

1. What is sizing in textiles?

Sizing is the application of a protective coating on warp yarns to improve weaving performance.

2. How do you measure size add-on?

By calculating weight difference before and after sizing.

3. What causes warp yarn brittleness?

Over-drying or excessive starch concentration.

4. How can uneven sizing be detected?

Through tensile testing, visual inspection, and add-on measurement.

5. Why is viscosity important in sizing?

It controls penetration, adhesion, and film formation.

References

TextileCoach – Sizing in Textile: QC Parameters (Add-on, Moisture, Strength, Elongation), 

https://www.textilecoach.net/post/sizing-in-textile-part-i

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Textile Learner – Sizing Defects, Causes and Remedies (Over/Under Sizing, Brittleness, Uneven Pick-Up), 

https://textilelearner.net/sizing-defects-causes-and-remedies/

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Textile Learner – Factors Affecting Size Add-On % on Warp Yarn (Pickup Control & Add-On Materials), 

https://textilelearner.net/size-add-on-materials/

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JEMIT – Sizing Efficiency and Cost Reduction Strategies (Hairiness, Tenacity, Viscosity, Weaving Efficiency), 

https://jemit.aspur.rs/archive/v3/n1/3.pdf

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JES KUET – Analysis of the Effect of Sizing Add-On % on Yarn Properties (Strength/Elongation), 

https://www2.kuet.ac.bd/JES/images/files/v13_2/11_JES_V13_2.pdf

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PMC – Hydroxypropylsulfonation/Caproylation of Cornstarch to Enhance Adhesion & Reduce Brittleness (Film Toughness, Viscosity Stability), 

https://pmc.ncbi.nlm.nih.gov/articles/PMC6680704/

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PMC – Novel Energy-Saving Environmentally Friendly Starch via Graft Copolymerization (Warp Sizing & Easy Removal), 

https://pmc.ncbi.nlm.nih.gov/articles/PMC10820382/

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Scribd – Overview of Textile Sizing Process (Strength, Smoothness, Hairiness Reduction), 

https://www.scribd.com/document/520555314/Study-on-Sizing-Process

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Slideshare – Sizing (Functions, Parameters, Defects Overview), 

https://www.slideshare.net/slideshow/sizing/37598595

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Scribd – Sizing Impact on Weaving Performance (Breaks, Efficiency, QC Links), 

https://www.scribd.com/document/888119273/TE-23051-TXE-2103

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UTS Testers – Controlling Sizing Equipment and Processes Can Reduce Hairiness (Role of Process Parameters), 

https://www.utstesters.com/blog/controlling-sizing-equipment-and-processes-can-reduce-hairiness_b56

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Tekmon – Quality Control in Textile Industry (General QC Framework & Checklists), 

https://www.tekmon.com/quality-control-in-textile-industry