School Blazer Fabric Specification
A local school has ordered 1,200 blazers for Years 10–11. The supplier must choose between two fabrics: (A) 65% polyester/35% cotton twill at £7.40 per metre, 150 cm wide, and (B) 100% cotton twill at £9.10 per metre, 140 cm wide. Each blazer requires 1.8 m of fabric at the current marker efficiency of 82%. The school washes uniforms at 60°C and tumble-dries them. A pilot wash test of five cycles showed fabric A pilling grade 3–4 and shrinkage 1.2% warp/0.8% weft; fabric B pilling grade 2–3 and shrinkage 4.5% warp/3.0% weft. The school also wants a lower environmental impact and has asked about microfibre shedding. Delivery is in 10 weeks; both fabrics are in stock. The supplier has one opportunity to specify the fabric before cutting begins.
1. Recommend which fabric the supplier should specify. Justify your choice using the cost, performance and care evidence, and explain one risk of your recommendation.
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Recommendation: specify Fabric A (65/35 polyester/cotton).
Cost reasoning
- Fabric needed per blazer = 1.8 ÷ 0.82 = 2.195 m.
- Fabric A: 2.195 × £7.40 = £16.24 per blazer; 1,200 × £16.24 = £19,488.
- Fabric B: 2.195 × £9.10 = £19.97 per blazer; total = £23,964.
- Saving with A = £4,476, about 18.7% of the fabric budget.
Performance reasoning Fabric A shrinks only 1.2%/0.8%, which is within a typical ≤2% specification. Fabric B shrinks 4.5% in the warp; after the school’s 60°C wash and tumble-dry cycle, sleeves and hems are likely to shorten and the blazer may distort, causing complaints and returns. Fabric A also has better pilling resistance (3–4 versus 2–3), which matters for a garment worn daily and washed frequently. The polyester content gives wrinkle resistance and shape retention, useful for school uniform.
Risk of the recommendation Fabric A sheds microfibres, which conflicts with the school’s environmental question and could damage the supplier’s reputation. The supplier should acknowledge this and offer care guidance (for example a microfibre-catching wash bag) or investigate a recycled-polyester blend. Before cutting, a production sample should be washed five times to confirm the pilot results.
2. Describe a suitable test programme to check whether Fabric A will meet the school’s wash-care requirements, and explain how you would interpret the results against a specification.
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Test programme
- Dimensional stability: mark 500 mm benchmarks on three specimens in warp and weft. Wash to a defined domestic procedure (for example ISO 6330, 60°C, 5 cycles) and tumble-dry between cycles. Re-measure and calculate percentage change.
- Pilling: test washed specimens using a pilling box or Martindale method (for example ISO 12945-2), with at least three trained assessors.
- Colour fastness to washing: use ISO 105-C06 at 60°C; assess colour change and staining of adjacent multifibre strip against grey scales.
- Appearance after washing: assess seam puckering, creasing and distortion against a reference sample.
Specification and interpretation A workable specification would be: shrinkage ≤2.0% in warp and weft; pilling ≥4 after 5 washes; colour change ≥4 and staining ≥3–4. Fabric A’s pilot shrinkage (1.2%/0.8%) passes, but its pilling grade of 3–4 sits at or below the boundary. If the specification requires grade 4, Fabric A fails and the supplier must either negotiate a lower pilling requirement, apply an anti-pilling finish, or re-test a larger sample. Results must be compared with the unwashed control and with the school’s actual 60°C/tumble-dry routine, not just a gentle 40°C laboratory cycle.
3. Explain why the school might still prefer 100% cotton despite the test data, and what the supplier could do to reduce the shrinkage risk if cotton were chosen.
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Why the school might prefer cotton Cotton is breathable, soft against the skin, naturally derived and biodegradable, and it does not shed plastic microfibres. For adolescent wearers in heated classrooms, comfort and moisture absorption may be valued more than easy-care performance. The school may also have a sustainability policy that prioritises natural fibres and avoids fossil-fuel-derived polyester. Parental expectations about “natural” fabric can influence the decision even when the test data favour the blend.
Reducing shrinkage risk The supplier should not simply accept 4.5% shrinkage. Options include:
- Specify a pre-shrunk, compacted or sanforised cotton and obtain a shrinkage guarantee from the mill.
- Re-test the actual production lot, because the pilot may not represent bulk fabric.
- Increase seam and hem allowances, or adjust the pattern length, to accommodate expected shrinkage.
- Give a clear care label: wash at 40°C, do not tumble-dry, or wash before first wear if the school accepts this.
- Consider a cotton-rich blend with a small elastane or polyester content only if the school’s fibre policy permits it.
The trade-off is that cotton may cost more (£23,964 versus £19,488 for the order) and still perform less well in pilling. The supplier should present both options honestly with test evidence, rather than promising performance the fabric cannot deliver.