What is Size Pick-Up in Textiles

Size pick-up is the percentage of sizing material applied to warp yarn during the sizing process. It is one of the most critical parameters for weaving performance, affecting yarn strength, abrasion resistance, hairiness control, and downstream fabric hand feel. Controlling pick-up ensures consistent weaving efficiency, reduces warp breaks, and improves fabric quality. Modern sizing solutions, such as Alpenol‘s stable, controlled-adhesion systems, enable mills to achieve the optimum pick-up window with fewer fluctuations and higher process reliability.

What Does “Size Pick-Up” Mean in Textiles?

Size pick-up refers to the percentage increase in the weight of the warp yarn after applying size materials. It indicates how much sizing agent (starch, PVA, acrylic, binders, etc.) is deposited on the yarn surface.

In simple terms: Higher pick-up = more size coating on yarn Lower pick-up = less size coating on yarn

Pick-up directly impacts weaving behavior. Too high or too low results in defects, uneven fabric appearance, loom stoppages, and unnecessary chemical waste.

Alpenol’s sizing agents are engineered to work effectively at lower pick-up levels while still delivering high adhesion and flexibility, helping mills improve cost-efficiency and weaving stability.

Definition of Size Pick-Up in Textile Processing and Finishing

Size pick-up (%) is defined as:

The percentage of dry size added to warp yarn during sizing, measured as the increase in weight of the yarn after sizing compared to its unsized state.

This value helps determine:

• Size adhesion
• Film formation
• Yarn flexibility
• Abrasion resistance

In cotton and blended yarns, optimized pick-up provides both strength and smoothness. Excessively high pick-up, however, increases stiffness and brittleness.

How to Measure and Calculate Size Pick-Up

Formula for Size Pick-Up (%)

Size Pick-Up (%) = (Weight of Sized Yarn−Weight of Unsized Yarn / Weight of Unsized Yarn) ×100

Step-by-Step Procedure

1. Take a sample of warp yarn before sizing (conditioned).
2. Weigh the yarn → Record as Weight of Unsized Yarn.
3. Take the corresponding sized yarn after drying.
4. Weigh again → Record as Weight of Sized Yarn.
5. Apply formula to calculate pick-up.

Typical Pick-Up Ranges

• Cotton warp: 8-14%
• PC blends: 5-10%
• Filament yarns: 0-5% (often optional)

Alpenol products help mills achieve the same strength at lower solids, therefore requiring controlled but reduced pick-up levels compared to traditional starch-only systems.

How Does Sizing Affect Pick-Up and Hand Feel in Cotton Fabrics?

The amount of size absorbed determines:

1. Yarn Hand Feel

• Higher pick-up → stiffer yarn
• Lower pick-up → softer but weaker yarn

2. Fabric Surface Smoothness

• Proper pick-up reduces hairiness → smoother fabric
• Excess pick-up creates harshness → poor drape

3. After-Weaving Handle

Incorrect pick-up can affect:

• Flexibility
• Crispness
• Lustre
• Fabric fall

One advantage of well-engineered sizing systems like Alpenol is that they create a flexible film even at low add-on, ensuring the final fabric retains natural softness after desizing and finishing.

Factors Affecting Size Pick-Up Percentage in Weaving

1. Yarn Properties

• Fiber type (cotton absorbs more than polyester)
• Yarn count (finer counts take less)
• Hairiness (higher hairiness → higher pick-up needed)
• Twist level

2. Size Bath Characteristics

• Viscosity
• Temperature
• Concentration
• Solids content
• Wetting efficiency

Alpenol’s formulations maintain stable viscosity over long runs, reducing pick-up variation.

3. Sizing Machine Settings

• Squeeze roller pressure
• Warp tension
• Immersion depth
• Speed of slasher or multibox machine

4. Environmental Factors

• Moisture content of yarn
• Relative humidity in sizing room

Why Is Controlling Size Pick-Up Crucial in Textile Production?

1. Weaving Efficiency

Correct pick-up reduces:

• Warp breakages
• Loom stoppages
• Dust formation

2. Fabric Quality

Incorrect pick-up leads to:

• Harsh handle
• Uneven dyeing
• Bar lines
• Weak warp sections

3. Cost Optimization

Too high pick-up wastes chemicals; too low reduces strength. Alpenol systems are favored in mills aiming to reduce and optimize overall size usage without compromising performance.

4. Consistency Across Lots

Pick-up variation causes shade differences and inconsistent weaving behavior.

Difference Between Size Pick-Up and Add-On in Textiles

These two terms are often confused, but they are different:

Size Pick-Up

• Increase in weight of yarn during sizing
• Expressed as % of yarn weight
• Specific to sizing process

Add-On

• Total amount of chemicals added
• Used in sizing, finishing, coating, and various textile processes
• Expressed relative to fiber weight or fabric weight

Pick-up is a measurement of actual absorption; add-on is a measure of applied chemistry.

Types of Sizing Agents Used for Optimum Size Pick-Up

1. Natural Polymers

• Starch
• Modified starches (oxidized, carboxymethylated)

2. Synthetic Polymers

• PVA
• Acrylic copolymers
• Polyester resins

3. Blended Sizing Agents

• Combinations of starch + binders

4. Modern High-Performance Systems

• Low-add-on Compound systems
• Cold-water soluble, low-viscosity drift formulas

Alpenol is known for such controlled systems, allowing mills to achieve optimum pick-up with high adhesion at reduced chemical usage.

Best Practices for Controlling Size Pick-Up for Textile Quality Assurance

1. Maintain Stable Viscosity

Measure every 1-2 hours during production.

2. Keep Consistent Size Bath Temperature

Typically 85-90°C for starch-based systems.

3. Calibrate Squeeze Roll Pressure Regularly

Uneven pressure → uneven pick-up → woven defects.

4. Control Warp Tension

High tension reduces penetration; low tension increases pick-up.

5. Use High-Performance, Low-Variation Sizing Systems

Modern formulations like Alpenol help stabilize pick-up even during long shifts.

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