Knitwear QC Guide: Shrinkage, Pilling, and Tension Control for OEM/ODM Manufacturing

Why QC Matters in Knitwear Manufacturing

Unlike woven fabrics, knitwear is a loop-based structure that naturally stretches, shrinks, and reacts dynamically to tension, humidity, yarn twist, machine settings, and washing.
Poor QC leads to:

• Garment shrinkage beyond tolerance

• Uneven measurements

• Neck stretching

• Pilling after only 1–2 wears

• Fabric distortion

• Twisted side seams

• Inconsistent sizing across batches

OEM/ODM QC Responsibilities

A professional knitwear factory evaluates quality at four levels:

1. Yarn-level QC

2. Machine-level QC (knitting tension)

3. Panel-level QC (shape, size, shrinkage)

4. Finished-garment QC (pilling, appearance, fit)

Each step affects the next.

Shrinkage Control in Knitwear

What Causes Shrinkage in Knitwear?

Shrinkage occurs when knitted loops tighten during washing, steam finishing, or drying.
Major causes include:

• High yarn hairiness

• Low yarn twist

• Loose machine tension

• Unbalanced stitch density

• Wrong washing condition

• High agitation during laundry

• Fiber type (wool > viscose > cotton > synthetics)

Different fibers shrink differently, requiring unique control methods.

Shrinkage Standards for Brands

Typical Acceptable Shrinkage (after 1–3 washes)

• Cotton / cotton blends: 3–5%

• Viscose / modal / Tencel: 4–8%

• Wool / merino: 2–4%

• Acrylic / synthetics: <2%

• Wool blends: 2–3%

• Poly/cotton uniforms: <1%

Testing Standards

Shrinkage testing usually follows:

• ISO 6330 (most common)

• AATCC 135 (US brands)

Factories typically test shrinkage during:

• Yarn testing

• Panel washing

• First sample

• PPS (Pre-production sample)

• During bulk QC AQL checks

How Factories Control Shrinkage

Yarn-Level Prevention

Increase yarn twist

Higher twist = lower shrinkage risk.

Use pre-shrunk or steamed yarn

Especially important for viscose, wool, and cotton.

Knitting-Level Prevention

Tightening stitch density

Prevents loop relaxation.

Controlling machine tension

Unstable tension = unpredictable shrinkage.

Washing & Finishing Prevention

Pre-washing test panels

Before producing the full garment.

Gentle washing

Lower RPM, lower agitation.

Controlled drying

Tumble drying increases shrinkage for cotton/viscose.

Measurement Prevention

Over-measurement (positive ease)

Panels purposely knitted larger to compensate for shrinkage.

Common Shrinkage Problems & Solutions

Viscose/Modal/Tencel Shrinkage

• High shrinkage risk

• Fabric grows when wet, shrinks when dry
  Factory controls:

• Pre-shrinking

• Balanced tension

• High-twist viscose

• Reduced agitation washing

Wool Shrinkage (Felting)

• Wool fibers lock together during agitation
  Factory controls:

• Use Superwash wool

• Gentle wool washing programs

• Avoid high temperatures

Cotton Skewing / Twisting

• Caused by uneven yarn twist
  Factory controls:

• Use combed cotton

• Balanced knitting tension

Pilling Control in Knitwear

What Causes Pilling?

Pilling occurs when loose fibers on the yarn surface entangle and form small balls due to friction.

Primary pilling factors:

• Short fibers (recycled cotton, cashmere, low-grade wool)

• Low yarn twist

• Soft acrylic

• Loose stitches

• Friction during wear

• Improper finishing

Pilling Standards

Pilling Tests Used by Factories

• ISO 12945-2 (Martindale method)

• ASTM D4970

• Random Tumble Pilling Test (AATCC 151)

Typical Pilling Grades (1–5 scale)

• Grade 5 – No pilling

• Grade 4 – Excellent

• Grade 3 – Acceptable for fashion retail

• Grade 2 – Poor (reject)

• Grade 1 – Severe pilling (reject)

Brand Requirements

• Luxury brands: Grade 4–5

• High-street: Grade 3–4

• Fast fashion: Grade 3

• Uniforms: Grade 4+

How Factories Prevent Pilling

Fiber-Level Control

Choose long-staple fibers

Longer fibers = less hairiness.

Fiber blends

Nylon improves durability when blended with wool or viscose.

Yarn-Level Control

Increase yarn twist

Higher twist = fewer loose fibers.

Anti-pilling yarn technology

Mechanical or chemical surface treatment.

Knitting-Level Control

Adjust stitch density

Loose knits pill more easily.

Use plating or twist-support yarns

Adds stability to the face yarn.

Finishing-Level Control

Anti-pilling wash

Removes surface fuzz.

Shearing / singeing

Removes protruding fibers before washing.

Common Pilling Issues & Solutions

Soft Acrylic Sweaters Pill Easily

Solution: Use low-pilling acrylic blends or acrylic/nylon blends.

Viscose Pilling

Solution: Use high-twist viscose yarn + tighter stitch density.

Wool Pilling

Solution: Superwash wool or wool/nylon blends.

Cashmere Pilling

Solution: Longer cashmere fiber, higher twist, anti-pilling finishing.

Tension & Dimensional Stability in Knitwear

Why Tension Control Is Critical

Tension determines stitch size, fabric density, and panel shape.
Poor tension causes:

• Crooked panels

• Uneven sleeve lengths

• Neckline collapse

• Rib distortion

• Shrinkage inconsistency

• Misaligned jacquard/intarsia patterning

How Factories Control Tension

Machine-Level Control

Yarn feeder calibration

Ensures yarn enters the machine with consistent pull.

Take-down roller settings

Controls how tightly the knitted panel is pulled downward.

Machine humidity

Viscose, cotton, and wool behave differently in varying humidity.

Yarn-Level Control

Balanced twist

Uneven twist = panel skewing.

Lot consistency

Different yarn lots → inconsistent tension.

Panel-Level Control

Measure before & after washing

Factory compares pre-wash vs post-wash stability.

Common Tension Problems & Solutions

Panel Narrowing

• Too tight take-down tension

• Yarn too dry

Solutions: Lower tension, increase humidity.

Panel Growing (Too Wide)

• Loose tension

• Overfeeding yarn

Solutions: Increase stitch density and adjust feeder.

Rib Trims Stretching Out

• Low twist

• Loose rib structure

Solutions: Plated ribs / elastic yarn support.

Jacquard Pattern Distortion

• Uneven tension between colors

Solution: Individual feeder adjustment per color.

OEM/ODM QC Workflow (Factory Standard)

Stage 1: Yarn QC

Tests

• Count accuracy

• Twist

• Evenness (USTER)

• Tensile strength

• Moisture regain

• Hairiness

Stage 2: Knitting QC

Controls

• Tension consistency

• Needle condition

• Gauge precision

• Stitch size

• Panel shape

Stage 3: Washing & Finishing QC

Checks

• Shrinkage

• Skewing

• Colorfastness

• Hand-feel consistency

• Dimensional stability

Stage 4: Final QC

Inspection

• Full measurement

• Linking/seam strength

• Pilling test

• Visual defects

• Matching between panels

Factories use AQL standards (AQL 1.5–2.5 depending on brand requirements).