Knitwear Washing, Blocking & Stabilization: The Complete Finishing Engineering Guide

Why Finishing Determines Final Knitwear Quality

Finishing directly affects:

• post-wash measurements

• softness and hand-feel

• shrinkage stability

• yarn blooming and loft

• colorfastness to washing and rubbing

• tumbling performance

• long-term pilling resistance

• neckline and rib recovery

• body drape

• fabric appearance

Finishing is often called the “heart of knitwear production” because it is the only stage that finalizes the garment’s true fit, feel, and stability.

The Complete OEM Finishing Workflow

Finishing usually follows this sequence:

1. Pre-wash inspection

2. Washing (wet finishing)

3. Softening or specialty chemicals (optional)

4. Dehydration / Water extraction

5. Tumble pre-setting (if needed)

6. Measurement blocking

7. Steam setting & stabilization

8. Drying (air dry or tumble dry depending on fiber)

9. Final measurement calibration

10. Quality control & shrinkage verification

Each step is controlled based on fiber type, stitch structure, and garment weight.

Washing Programs for Different Fiber Types

Different fibers require different wash programs.

Wool / Merino Washing

Wool is sensitive to:

• agitation

• heat

• pH imbalance

Wool finishing program includes:

• low RPM rotation

• temperature 20–30°C

• wool-safe detergent

• short dehydration cycle

• anti-shrink treatment

This ensures wool garments do not felt, shrink excessively, or lose elasticity.

Cashmere Washing

Cashmere is extremely delicate.

Program characteristics:

• cold water (15–20°C)

• minimal mechanical action

• high-end softener

• no tumble drying

• slow air drying with blocking

Cashmere develops its final softness only after gentle wet finishing.

Cotton Washing

Cotton can handle stronger washing but requires shrinkage control.

Program characteristics:

• 30–40°C

• medium agitation

• enzyme treatment (optional)

• controlled dehydration

Enzyme washing can reduce hairiness and improve surface smoothness.

Viscose / Modal / Tencel

Regenerated fibers absorb high water weight and stretch when wet.

Program characteristics:

• cold water

• no mechanical stretching

• careful lifting

• slow dehydration

• strict blocking

These fibers must be stabilized properly to avoid growth during wear.

Acrylic / Synthetic Blends

Very stable and easy to finish.

Program characteristics:

• warm water (30°C)

• normal agitation

• quick dehydration

• tumble drying allowed for some blends

Acrylic often achieves excellent dimensional stability.

Anti-Pilling Treatments

Pilling is influenced by:

• fiber length

• yarn twist

• stitch type

• washing and softening

• finishing chemistry

Factories apply anti-pilling treatments through:

Low-Impact Chemical Anti-Pill

Creates a protective layer on the fiber surface.

Enzyme Treatment

Removes loose hairs on cotton/viscose.

Steam Setting

Stabilizes surface fibers.

High-Twist Yarn Compensation

Adjusting finishing to reduce fuzzing.

Factories test pilling using ISO 12945.

Keywords targeted:

• anti-pilling sweater manufacturer

Colorfastness Optimization

Colorfastness is improved during finishing:

• using low-pH rinses

• reducing leftover dye particles

• applying color stabilizer chemicals

• avoiding excessive friction

• lowering dehydration RPM

Factories test:

• colorfastness to washing

• colorfastness to rubbing

• staining on multi-fiber test cloth

Keywords:

• colorfast sweater supplier

Shrinkage Control & Measurement Stabilization

Shrinkage is the #1 technical challenge in knitwear.

How factories control shrinkage:

• pre-shrink washing

• proper agitation level

• chemical stabilization

• blocking to exact dimensions

• calibrated steam setting

• yarn relaxation management

Typical shrinkage ranges after finishing:

Keywords:

• knitwear shrinkage control service

• pre-shrunk knitwear manufacturer

Blocking & Measurement Calibration

Blocking is the phase where garments are shaped to precise specifications.

Key blocking steps:

1. Lay garment on measurement template

2. Shape body width, length, sleeve length

3. Shape shoulder slope

4. Adjust neckline curve and opening

5. Ensure rib heights match target

6. Pin or clip corners to secure shape

7. Steam lightly to set the form

Blocking is crucial for:

• viscose/nylon blends

• women’s fashion sweaters

• heavy-gauge wool knits

• dresses and skirts

Blocking determines the proper silhouette and ensures the spec matches PPS approval.

Steam Setting & Final Stabilization

Steam setting “locks” the garment’s final dimensions.

Factors in steam setting:

• temperature (110–130°C)

• steam duration

• pressure

• panel tension

• rib elasticity balancing

• neckline stabilization

Steam setting improves:

• fiber memory

• measurement consistency

• wrinkle removal

• drape and softness

Factories use:

• steam chambers

• high-pressure steam guns

• steam tunnels (for large orders)

Specialty Finishing Techniques

Advanced finishing creates differentiated knitwear.

Brushing

Adds loft and softness (used for angora/mohair look).

Peach Finish

Creates a velvety surface.

Mercerization (Cotton)

Improves luster and dye uptake.

Anti-Felting

Used for wool and merino.

Silicon Softening

Improves hand-feel on synthetics.

Fabric Weight Adjustment

Wet finishing can increase or decrease garment weight.

Finishing for Different Product Categories

Women’s Fashion Knitwear

Needs:

• soft drape

• precise blocking

• stabilized rib openings

• color brilliance

Men’s Office Knitwear

Needs:

• stable measurements

• minimal shrinkage

• clean neckline

Streetwear

Needs:

• heavy-weight finishing

• controlled blooming

• high durability

Uniform Knitwear

Needs:

• anti-pilling

• colorfastness

• strong seams

• consistent shrinkage

Kids Knitwear

Needs:

• soft, hypoallergenic finishing

• controlled neckline stretch

• safe trims

Common Finishing Problems & Factory Solutions

Problem: Garment Shrinks Too Much

Cause: aggressive wash
Solution: lower agitation, adjust temperature, refine softener ratio

Problem: Color Fades After Washing

Cause: leftover dye
Solution: add color stabilizer

Problem: Neckline Loses Shape

Cause: rib tension imbalance
Solution: re-block & re-steam with rib reinforcement

Problem: Pilling Appears After Washing

Cause: insufficient fiber stabilization
Solution: enzyme wash or anti-pill chemical

Problem: Body Twisting

Cause: uneven tension or skewed stitches
Solution: adjust blocking & finishing sequence

Finishing Machines Used in OEM Knitwear Factories

Industrial Washing Machines

Preset textile programs for different fibers.

Hydro Extractors

High G-force dehydration without stretching fabric.

Tumble Dryers

Used only for stable fibers.

Steam Chambers

For large-batch stabilization.

Flat Drying Tables

Essential for viscose and cashmere.

Pressing & Steaming Stations

Used for final silhouette correction.

Inline QC During Finishing

Factories monitor:

• shrinkage rate

• colorfastness

• seam stability

• rib elasticity

• neckline dimensions

• garment weight

• surface uniformity

• pilling grades

QC checkpoints ensure bulk production remains identical to PPS approval.

Finishing for Export Requirements

Factories must meet:

• EU REACH compliance

• US AATCC washing standards

• ISO colorfastness

• carton humidity control

• odor-free packing

• correct folding methods

Export knitwear must pass moisture, weight, and surface appearance checks to avoid shipping issues.

Environmental & Sustainable Finishing Solutions

Sustainable brands request:

• low-liquor dyeing

• ozone finishing

• enzyme-based bio finishing

• water-saving industrial washing

• recycled water systems

• biodegradable softeners

These reduce environmental impact without compromising garment quality.