The Shrinking School Uniform Order
A parent brings in 4 m of a 100% cotton twill bought online, labelled "pre-shrunk, maximum shrinkage 3%." The fabric is 150 cm wide. She wants two identical school skirts for her daughters, each needing a cut piece 70 cm long on the lengthwise grain and 140 cm wide before seam allowance. She has already washed the fabric once in warm water and tumble-dried it hot, and now the piece measures 3.85 m by 147 cm. She asks you to cut both skirts from what remains. You know the skirts will be washed weekly in warm water and tumble-dried, and the school requires hems of at least 4 cm.
1. Using the measured figures, decide whether both skirt pieces can be cut from the remaining fabric, showing your calculation.
Read the worked answer
First work out what the fabric can actually yield after the wash it has already had.
- Length now: 385 cm. Each piece needs 70 cm, so 2 × 70 = 140 cm plus hem and seam allowances. Even allowing 10 cm per skirt for hems and waist finishing, that is 160 cm - well within 385 cm.
- Width now: 147 cm. Each piece needs 140 cm across the width, which leaves only 7 cm spare. That is the binding constraint, not length.
So the answer is yes on length but marginal on width. The 140 cm requirement plus a 1.5 cm seam allowance on each side gives 143 cm, which still fits inside 147 cm with 4 cm to spare. Both skirts can be cut side by side across the width if the pattern pieces are placed with their long edges parallel to the selvedge. The limiting factor is that any further shrinkage would make the width insufficient, so the pieces must be cut now and the remaining offcuts kept for pockets or waistbands.
2. The label claimed 3% maximum shrinkage, yet the fabric shrank more. Explain what likely happened and advise the parent on how to treat the finished skirts.
Read the worked answer
Measure the actual shrinkage: length went from 400 cm to 385 cm, a loss of 15 cm, which is 3.75%. Width went from 150 cm to 147 cm, a loss of 3 cm, or 2%. The length figure exceeds the stated 3% maximum, so either the label was inaccurate or the hot tumble dry exceeded the conditions the manufacturer tested under. "Pre-shrunk" usually means the fabric was mechanically or chemically shrunk during finishing, not that it will never shrink again; cotton relaxes and shrinks further with heat and agitation.
Advice to give:
- Pre-wash any leftover fabric the same way before using it for pockets, so those pieces do not pucker after the skirt is washed.
- Wash the finished skirts in warm water (around 40 °C) rather than hot, and avoid a hot tumble dry - line dry or use a low setting. Residual shrinkage in cotton continues over the first few washes.
- Cut generous hem allowances (5–6 cm rather than the minimum 4 cm) so that if the skirt shortens in later washes the hem can be let down and still meet the school's 4 cm rule.
- Keep a record of the wash conditions so the parent can show the retailer if she wants to complain about the inaccurate label.