Shrinkage Testing
Laboratory or practical testing to measure how much a fabric or garment shrinks after washing, drying, and steaming — critical for accurate sizing.
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What is Shrinkage Testing?
Shrinkage testing measures the dimensional change (usually reduction) in fabric or garment size after washing, drying, or steaming. It is one of the most important quality tests in fashion manufacturing — if shrinkage is not accounted for, garments will be too small after the first wash, leading to returns and customer dissatisfaction.
Types of shrinkage:
- Relaxation shrinkage: Fabric relaxing from tension applied during weaving/finishing — occurs in the first wash
- Progressive shrinkage: Gradual shrinkage over multiple wash cycles
- Felting shrinkage: Specific to wool — fibres interlock when agitated
- Thermal shrinkage: Heat-induced shrinkage from tumble drying or steam pressing
Testing methods:
- ISO 6330: Standard domestic washing and drying procedures
- AATCC 135: American standard for dimensional change in laundering
- Fabric marking method: Mark a 50cm × 50cm square on fabric, wash, measure change
- Garment wash method: Measure garment before and after washing at key points
Shrinkage expectations by fabric:
- Cotton (untreated): 3–8% length, 2–5% width
- Cotton (pre-shrunk/sanforised): 1–2%
- Linen: 4–10% (higher than cotton)
- Polyester: 0.5–1%
- Silk: 3–5%
- Wool: 5–15% if not treated (felting)
- Rayon/viscose: 5–10% (notorious for high shrinkage)
Why This Matters for Fashion Entrepreneurs
Shrinkage is the number one cause of sizing complaints in Indian fashion e-commerce. If a customer buys a Medium and it becomes a Small after one wash, you lose the customer and incur return shipping costs.
Prevention strategy:
- Test every fabric lot: Shrinkage varies between lots even from the same supplier
- Pre-shrink fabric or garments: Garment washing or fabric pre-shrinking eliminates the problem
- Cut with shrinkage allowance: If you know a fabric shrinks 5%, cut garments 5% larger
- Specify on care labels: Accurate care instructions prevent unnecessary shrinkage
Cost of getting it wrong:
A 5% sizing error on 500 garments at ₹500 average retail = ₹2,50,000 in potential returns, re-shipping, and refunds. A ₹1,000 shrinkage test prevents this entirely.
Sourcing Guide
Shrinkage testing options:
- In-house testing: Mark a sample, wash per care label instructions, measure — simple and free
- Factory testing: Most production factories can conduct basic shrinkage tests
- Independent labs: ATIRA, BTRA, SITRA, SGS, Intertek — certified testing
- Fabric supplier: Request shrinkage data with every fabric purchase
What to request from fabric suppliers:
- Shrinkage test report (both length and width)
- Test method used (ISO 6330 or AATCC 135)
- Number of wash cycles tested
- Drying method used in test (line dry vs tumble dry)
Pricing & Costs
Shrinkage testing costs:
- In-house test (fabric + wash): ₹0 (your time + water/detergent)
- Factory-conducted test: Usually included in quality checks
- Independent lab test: ₹500–1,500 per fabric sample
- Comprehensive dimensional stability test: ₹1,500–3,000
Pre-shrinking options:
- Fabric pre-shrinking (compressive/sanforising): ₹3–8 per meter
- Garment washing (includes pre-shrinking benefit): ₹8–30 per piece
Both are extremely cost-effective relative to return handling costs.
Frequently Asked Questions
Simple DIY method: (1) Cut a 50×50 cm fabric square, (2) Mark a 30×30 cm square inside with permanent marker, (3) Wash per your care label instructions, (4) Line dry or tumble dry per care label, (5) Measure the marked square — percentage change = shrinkage. Repeat 3 times for reliability. This takes 1–2 hours and costs nothing.
Pre-shrink fabrics with >2% expected shrinkage (cotton, linen, rayon, silk). Synthetic fabrics (polyester, nylon) with <1% shrinkage usually don't need pre-shrinking. Blends depend on the ratio — a 70/30 cotton-poly will shrink less than 100% cotton but still needs attention. When in doubt, pre-shrink. The cost is minimal (₹3–8/m for fabric, ₹8–30 per garment) and prevents problems.
Fabrics shrink more in the direction where yarns are under more tension during production. Typically, warp direction (length) has higher tension than weft (width), so length shrinkage exceeds width shrinkage. Knit fabrics can shrink more in width due to loop structure. This is why shrinkage is always reported as length × width (e.g., "5% length, 3% width"). Account for both dimensions in your pattern adjustments.
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