Why Is the Sizing Process Important?

Sizing prepares warp yarns for the intense stresses of weaving. Without proper sizing:

• Abrasion at heddles and reeds increases

• End-breaks rise

• Loom stoppages multiply

• Fabric quality drops

• Production cost increases

Sizing creates a protective polymer film around yarns, improving:

• Strength

• Cohesion

• Smoothness

• Flexibility

In mills operating high-speed air-jet or rapier looms, stable and controlled sizing chemistry (like Alpenol’s low-add-on, high-adhesion systems) reduces variability and enhances weaving efficiency.

What Are the Checkpoints to Carry Out the Sizing Process Successfully?

Successful sizing is monitored across three stages:

1. Pre-Sizing Checkpoints

A. Yarn Quality Assessment

• Count consistency

• Twist level

• Hairiness

• Moisture content

• Fiber composition

Spun yarns with high hairiness demand stronger, flexible films; Alpenol formulations help compensate for these variations.

B. Size Recipe Validation

• Polymer selection (starch, PVA, acrylic blends)

• Solids concentration

• Additive compatibility

• Expected viscosity curve

C. Size Bath Preparation

• Proper dissolution

• Homogeneous mixing

• No lumps or gels

• Temperature stabilization (85–90°C typical for starch-based systems)

2. In-Process Checkpoints

A. Viscosity Monitoring

• Must remain within the standard window

• Measured every 1–2 hours

• Viscosity drift is a major cause of uneven pick-up

Alpenol’s stable rheological profile reduces drift and simplifies in-process control.

B. Size Pick-Up Control

• Ensure uniformity across warp sheet width

• Avoid over/under pick-up

• Use immersion depth, tension, and roller pressure adjustments

C. Squeeze Roller Pressure

• Uniform nip pressure

• No misalignment

• Roll hardness and wear checked regularly

D. Drying System

• Cylinder temperatures balanced

• Moisture content target (6–12% depending on yarn type)

• Over-drying → brittle yarn

• Under-drying → sticky yarn

3. Post-Sizing Checkpoints

A. Yarn Strength Testing

• Tensile strength improvement (ideally 15–25% increase)

• No brittle feel

B. Hairiness Reduction

• Smooth surface

• Reduced protruding fibers

• Measured via hairiness testers

C. Adhesion & Film Uniformity

• No flaking

• No powdering

• No sticking

• Film should be flexible and intact

D. Beam Build Quality

• Even tension

• No slack ends

• No overlapping or snarls

E. Loom Trial Performance

• Fewer end-breaks

• Stable warp sheet

• No excessive dust

Alpenol’s film-forming chemistry is designed to remain flexible even at lower add-on, improving success rates on beam performance and loom trials.

How Do You Know the Sizing Process Was a Success?

A sizing process is considered successful when the following technical metrics are met:

1. Target Size Pick-Up Achieved

Pick-up must be within the specified range for the yarn type.
For cotton → typically 8–14%.
Lower pick-up is possible with high-performance agents like Alpenol.

2. Improved Tensile Strength

Warp yarn strength should improve by at least 15–25%.
Strength consistency across samples is equally important.

3. Reduced Hairiness

Significant drop in surface fuzz and protruding fibers.

4. Cohesive & Flexible Size Film

The film should not crack or powder.
Flexibility ensures smooth shedding and beating-up.

5. Uniform Moisture Content

Target regain levels ensure correct yarn bending stiffness.

6. Low End-Break Rate in Loom Trials

A clear success indicator:

• Less warp shedding failure

• Fewer stoppages

• Better loom efficiency

Warp beams sized with Alpenol often show lower breakage and dust, particularly in spun yarn fabrics.

7. Smooth Warp Sheet Movement

No sticking, tangling, or roller deposits.

8. Clean Beam Build

No variation in tension across beam flanges.

What Are the Common Problems That Occur in Sizing?

How Are Problems in Sizing Solved?

1. Fixing Uneven Pick-Up

• Stabilize viscosity

• Adjust squeeze pressure

• Improve size circulation

• Ensure roller alignment

2. Preventing Flaking and Brittleness

• Increase moisture content slightly

• Reduce solids or adjust polymer blend

• Use flexible-film chemistries

3. Avoiding Sticky Yarn

• Raise drying temperature slightly

• Reduce plasticizer content

4. Improving Yarn Adhesion

• Modify size recipe

• Strengthen starch/PVA/acrylic balance

• Use high-adhesion engineered size agents

5. Reducing Hairiness

• Increase penetration

• Raise pick-up slightly

• Optimize pretension

Summary: What Proves Sizing Was Done Correctly?

A successful sizing process will show:

• Uniform size pick-up

• Higher strength

• Reduced hairiness

• Flexible film formation

• Low end-breaks during weaving

• Clean, smooth warp movement

• Stable loom efficiency

• Reduced dust, reduced deposition

• Excellent beam build quality

Alpenol’s modern sizing systems help mills achieve these outcomes at lower chemical usage and with more predictable control—making sizing success more repeatable and less operator-dependent.

FAQ

1. How do you know if sizing is successful?

Check strength, pick-up, hairiness, film flexibility, moisture content, and loom performance.

2. What is the most important sizing parameter?

Uniform size pick-up—without it, film quality and strength become inconsistent.

3. How can I reduce sizing defects?

Stabilize viscosity, control temperature, calibrate rollers, and use reliable sizing formulations.

4. Why does sizing affect weaving?

It protects warp yarn from mechanical stress, reducing breakages and improving fabric quality.

5. Does the type of sizing agent matter?

Yes. Starch-only systems can be brittle; blended or engineered systems like Alpenol create stronger, more flexible films.

References

1. Textile School – Warp sizing fundamentals
   https://www.textileschool.com/articles/warp-sizing/

2. Textile Learner – Sizing process & QC
   https://textilelearner.net/sizing-in-textile/

3. AATCC Standards – Tensile & abrasion testing
   https://www.aatcc.org/testing/

4. NPTEL – Fabric manufacturing and sizing technology (IIT)
   https://nptel.ac.in/courses/116/102

5. ScienceDirect – Sizing film formation & adhesion studies
   https://www.sciencedirect.com/topics/engineering/sizing

Indian Textile Journal – Advances in sizing controlhttps://indiantextilejournal.com