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Training Manual — Section 4

Wash & Shrinkage

Shrinkage types and test methods, industrial wash processes, care symbols, and common wash problems.

Contents

01Types of Shrinkage02Shrinkage Test Method03Wash Types04Wash Care Symbols05Common Wash Problems06Dimensional Stability Control07Industrial Wash Process Control
Types of Shrinkage
Section 01

Types of Shrinkage

The four major shrinkage types and their causes.

1. Relaxation Shrinkage

  • Happens when fabric tension is released
  • Common in knits
  • Occurs during first wash

2. Felting Shrinkage

  • Wool fibers interlock
  • Caused by agitation + heat
  • Permanent shrinkage

3. Washing Shrinkage

  • Caused by water absorption
  • Cotton and viscose are most affected
  • Controlled by pre-shrinking

4. Heat Shrinkage

  • Caused by high dryer temperature
  • Synthetic fibers melt or deform
  • Avoid high heat

Quality Checkpoints

  • Shrinkage tolerance: ±3%
  • Measure before and after wash
  • Check length + width shrinkage
Shrinkage Test Method
Section 02

Shrinkage Test Method

Step-by-step process for measuring fabric shrinkage.

Step-by-Step Process

  • 1. Mark fabric/garment with 50cm × 50cm box
  • 2. Wash according to care label
  • 3. Dry flat or tumble dry (as required)
  • 4. Re-measure the box
  • 5. Calculate shrinkage percentage

Formula

  • Shrinkage (%) = (Original − Final) / Original × 100

Quality Checkpoints

  • Accurate marking
  • Correct wash cycle
  • Correct drying method
  • Proper measurement tools
Wash Types
Section 03

Wash Types

Industrial wash processes and their effects on fabric.

1. Enzyme Wash

  • Softens fabric
  • Removes fuzz
  • Used for denim, knits

2. Stone Wash

  • Creates worn look
  • Uses pumice stones
  • Risk: abrasion damage

3. Acid Wash

  • High contrast effect
  • Chemical spray + stones
  • Fashion denim

4. Softener Wash

  • Improves hand feel
  • Adds smoothness
  • Used for knits

5. Bio Wash

  • Enzyme treatment
  • Reduces pilling
  • Eco-friendly

Quality Checkpoints

  • Even wash effect
  • No over-washing
  • No fabric damage
  • Color consistency
Section 04

Wash Care Symbols

Major care symbols that guide garment maintenance.

Major Symbols

  • Machine wash
  • Hand wash
  • Do not bleach
  • Tumble dry
  • Line dry
  • Iron (low/medium/high)
  • Dry clean

Quality Checkpoints

  • Correct symbol usage
  • Based on fabric type
  • Based on garment construction
Common Wash Problems
Section 05

Common Wash Problems

Frequent issues encountered during washing, their mechanisms, and corrective actions.

Appearance Failures

  • Bleeding: improve dye fixation, after-wash, and colour separation
  • Pilling: review fibre, yarn, singeing, enzyme action, and abrasion
  • Creasing: correct load, liquor ratio, rotation, cooling, and unloading
  • Back staining: optimize dispersing agent, bath cleanliness, and rinsing
  • Uneven effect: stabilize loading, chemistry, temperature, and machine action

Dimensional Failures

  • Excess shrinkage: improve compaction and validate care cycle
  • Spirality: control yarn twist, knitting direction, finishing skew, and panel relaxation
  • Seam puckering: match thread, seam construction, differential feed, and material shrinkage
  • Growth: review elastane recovery, heat setting, and drying method

Corrective Workflow

  • Contain the affected lot and preserve machine-batch traceability
  • Compare approved standard, recipe, machine chart, and actual parameters
  • Test fabric, garment panels, trims, print, and thread separately
  • Run controlled trials changing one causal variable at a time
  • Approve rewash only after risk assessment and pilot confirmation

Quality Checkpoints

  • No uncontrolled rewash
  • Approved visual standard used
  • Root cause and corrective action documented
Section 06

Dimensional Stability Control

Engineering shrinkage, growth, spirality, and shape retention from fabric development through bulk production.

Test Protocol

  • Condition specimens under the specified atmosphere before marking
  • Use reference marks appropriate to fabric or garment test method
  • Apply specified wash, detergent, ballast, temperature, and drying cycle
  • Relax and recondition specimens before final measurement
  • Calculate each direction separately; negative values indicate growth

Production Controls

  • Set fabric relaxation time before spreading and cutting
  • Use shrinkage-adjusted patterns only from approved test evidence
  • Verify compaction, stenter overfeed, width, GSM, and residual shrinkage
  • Test every colour, fabric lot, wash route, and critical trim combination
  • Trend results and stop bulk before tolerance drift becomes systemic

Quality Checkpoints

  • Test method matches care label
  • Length and width reported separately
  • Buyer tolerance overrides generic ±3% guidance
Section 07

Industrial Wash Process Control

Repeatable bulk washing through recipe governance, machine control, chemical safety, and batch traceability.

Critical Parameters

  • Garment load, liquor ratio, water quality, and pH
  • Chemical identity, concentration, dosing sequence, and contact time
  • Temperature ramp, peak temperature, rotation, and mechanical action
  • Rinsing, neutralization, extraction, drying, and garment moisture
  • Machine type, capacity, calibration, maintenance, and cleanliness

Approval & Safety

  • Approve pilot and first bulk against sealed standard under controlled lighting
  • Verify SDS, PPE, chemical compatibility, storage, and dispensing controls
  • Monitor wastewater parameters and restricted-substance requirements
  • Record recipe version, operator, machine, batch, times, and deviations
  • Quarantine off-standard batches pending authorized disposition

Quality Checkpoints

  • Recipe version controlled
  • Bulk shade and hand feel within standard
  • Safety and environmental records complete

Continue your training

Explore the fabric knowledge manual and the full module library.

Fabric knowledge

Advanced reference

Technical controls & troubleshooting

Process Engineering

  • Define liquor ratio, loading factor, bath temperature, pH, time, rotation, and chemical sequence
  • Validate desizing before abrasion or enzymatic treatment of denim
  • Select cellulase type and activity to control surface cleaning without strength loss
  • Neutralize enzymes and oxidants completely before softening and drying
  • Control hydro-extraction and dryer temperature to prevent creasing and excess shrinkage
  • Approve wash standard using shade, hand feel, measurements, strength, and appearance

Dimensional Standards

  • Measure dimensional change to ISO 5077 after ISO 6330 laundering
  • Mark specimens with stable reference points and measure without tension
  • Report length, width, skew, bow, spirality, and seam torque separately
  • Use positive values for shrinkage and negative values for growth consistently
  • Apply care-label drying method because tumble and line drying produce different results
  • Confirm garment measurements after the specified number of wash cycles

Process Controls

  • Verify washing and shrinkage at incoming, first-output, inline, end-line, and final stages
  • Separate critical, major, and minor defects using the approved defect library
  • Use risk-based sampling; increase frequency after a failure or process change
  • Maintain shade, size, lot, roll, and bundle traceability throughout production
  • Quarantine nonconforming output until disposition and corrective action are approved
  • Confirm corrective action effectiveness on consecutive production checks

Troubleshooting

  • Contain affected wash output and identify the last verified-good checkpoint
  • Use 5 Why and fishbone analysis across material, machine, method, people, and environment
  • Compare failed output with the sealed sample, specification, and machine settings
  • Correct the root cause rather than relying on repeated inspection or repair
  • Run a controlled trial, validate results, then release the updated process setting
  • Update SOP, control plan, training record, and preventive-maintenance requirement

Written by Sanjeewa Dehiwalage — www.nosk.life — All rights reserved.

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