Six hundred uniforms and a cheaper tender
A government school in a district where summer temperatures cross 42 °C and relative humidity stays above 75% for five months is buying uniforms for 600 students. The budget is ₹320 per uniform, of which about ₹60 is stitching; each uniform needs 1.4 m of fabric. Three samples were tested by a laboratory. Sample A: 100% cotton, 180 GSM, plain weave - shrinkage 6% warp and 5% weft, colour fastness to washing 3 and to rubbing 3, tensile strength 280 N, air permeability 320 mm/s, pilling rating 4; ₹150/m. Sample B: 67:33 polyester–cotton, 200 GSM, twill - shrinkage 1.5%/1.0%, fastness 4–5, strength 420 N, air permeability 90 mm/s, pilling 3; ₹185/m. Sample C: 100% polyester knit, 150 GSM - shrinkage 1%, fastness 4, strength 350 N, air permeability 40 mm/s, pilling 2; ₹110/m. The accountant is pressing for C on cost grounds; the principal fears children fainting in the heat; the PTA says polyester uniforms 'last longer and need no ironing'.
1. Which sample would you recommend, and why? Is any sample to be rejected outright?
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Reject C outright. Air permeability of 40 mm/s is the lowest of the three, and with 42 °C and 75% humidity, sweat cannot evaporate; a 100% polyester knit also absorbs almost no moisture, holds heat, builds static and, with pilling rated 2, will look shabby within a term. Knit also stretches out of shape in a uniform that is worn and washed hard.
Recommend B, with two conditions. It offers the best balance: strength 420 N, low shrinkage, fastness 4–5 and easy care, at ₹319 per uniform - inside the ₹320 budget. Its weakness is air permeability of 90 mm/s, roughly a third of cotton's. So the tender must specify a minimum air permeability (say ≥100 mm/s) and a loose, non-body-fitting cut; if the supplier's fabric tests below that, the fabric is not acceptable for this climate whatever its price.
A is comfortable (320 mm/s) and the cheapest fabric, but 6% warp shrinkage means buying about 1.48 m instead of 1.4 m, fastness 3 predicts visible fading and colour bleed, and 280 N is the weakest. It is defensible only if the tender specifies pre-shrunk, colour-fast cotton and accepts ironing and a shorter life.
The judgement: comfort and durability are not opposites here - B is both affordable and serviceable, but only with a performance specification attached.
2. Explain to the purchase committee what each test measures and what the tender document should require. Which test standards should be cited?
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Shrinkage (dimensional change after washing): how much the garment shortens; above 2–3% a uniform stops fitting after a few washes. Specify: ≤2% in warp and weft.
Colour fastness to washing and to rubbing: resistance to colour loss and to transfer onto skin and other clothes, rated 1–5. Specify: ≥4 for both, since uniforms are washed frequently and children sweat heavily.
Tensile strength: the force at which the fabric breaks; low values mean seam failure at knees and elbows. Specify: ≥300 N.
GSM: mass per unit area, a proxy for thickness and durability; 180–200 GSM is appropriate for shirting.
Air permeability: volume of air passing through a unit area - the single most important comfort property in a hot, humid district. Specify: ≥100 mm/s, together with a stated moisture regain or blend composition.
Pilling: formation of fibre balls on the surface, rated 1–5; poor pilling makes a uniform look old and can cause skin irritation. Specify: ≥4.
Standards to cite: ISO 6330 (domestic washing procedure for shrinkage), ISO 105 series (colour fastness), ISO 13934-1 (tensile strength), ISO 9237 (air permeability), and require a test report from an NABL-accredited laboratory with the tender sample retained as the reference piece.
3. The accountant says C saves about ₹105 per uniform, or ₹63,000 across 600 students. Work out the counter-argument using cost per wear and the shrinkage allowance.
Read the worked answer
Purchase cost per uniform (1.4 m fabric + ₹60 stitching):
- A: 1.4 × 150 = 210 + 60 = ₹270
- B: 1.4 × 185 = 259 + 60 = ₹319
- C: 1.4 × 110 = 154 + 60 = ₹214
So C is ₹105 cheaper than B and ₹56 cheaper than A at the counter.
But A needs 6% extra fabric to allow for shrinkage: 1.48 × 150 = 222 + 60 = ₹282.
Expected service life (school use, washed twice weekly): A about 1.5 years before fading and shrinkage make it unwearable; B about 3 years; C about 1 year, because pilling rated 2 and knit distortion appear within two terms.
Cost per wear (200 school days a year):
- A: 282 ÷ (1.5 × 200) = ₹0.94
- B: 319 ÷ (3 × 200) = ₹0.53
- C: 214 ÷ (1 × 200) = ₹1.07
The cheapest tender is the most expensive per wear, roughly twice B. Add the hidden costs the accountant has not counted: mid-year replacement of 600 uniforms, disruption to uniformity, parent complaints and a fresh tender. The ₹63,000 'saving' is a saving only on the invoice, not on the school's actual spend.