Shrinkage and Twist After Cutting Cotton Poplin
A factory receives 1,200 m of 100% cotton poplin for 600 school shirts on Monday. Cutting starts the same afternoon because the delivery date is tight. No shrinkage test is done, and the rolls are cut immediately after unwinding. The marker uses the buyer's approved pattern: 72 cm body length and 10 mm seam allowance. After the first 20 shirts are washed at 40 degrees Celsius and tumble-dried, the body length measures 69.2 cm and the side seams twist on 12 panels; the front placket pulls. The cutting master says the fabric was on the roll so it should be stable, and proposes adding 3 cm only to the hem of the remaining pieces. The supplier's label gives no shrink information. The buyer's tolerance is plus or minus 1 cm on body length and no visible twist when worn.
1. Explain the 69.2 cm result and the twisted side seams. Show the calculation.
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The washed length is 69.2 cm against 72 cm, so the garment is 2.8 cm short. Calculation: 2.8 divided by 72, multiplied by 100, equals about 3.9%. The fabric is shrinking about 4% in length. The pattern and marker had no shrinkage allowance, and the fabric was cut immediately after unwinding, so the garment could only shrink after washing.
The twist is a grain problem: panels were cut off-grain, or the fabric was not relaxed and aligned before cutting. The side seams follow the skew. Because twist appears on only 12 panels, it is not explained by shrinkage alone. Both causes must be corrected; adding length will not fix twist.
2. Evaluate the cutting master's proposal to add 3 cm only to the hem of the remaining pieces.
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The proposal is not acceptable. Adding 3 cm roughly covers the 4% length shrink (72 multiplied by 0.04 equals 2.88 cm), but only at the hem. It changes body proportion, pocket position, placket length, side vents and hem allowance, and may break the approved pattern. It does not address width shrinkage, so chest and collar may also be undersize, and it does not correct twist.
The proper correction is a wash test on the actual lot, then adjust the pattern in length and width with buyer approval, re-mark and re-cut on grain. Quarantine the 20 shirts and any cut panels. Do not mix corrected and uncorrected pieces in one lot.
3. Set out the cutting-room actions before the remaining fabric is cut.
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Cut a test swatch from each roll, wash and dry it under the buyer's stated conditions, and measure length and width shrinkage. Let the rolls relax flat for at least 24 hours before spreading; align the grain and check skew. Adjust the pattern or marker with the measured allowance and obtain buyer approval if dimensions change. Mark grainline, notches and pieces clearly. Spread without tension and do not stretch fabric to match marker length. Cut, bundle and label by roll, and keep test records. Cut a first garment and wash-test it before bulk. If the fabric cannot meet tolerance, tell the buyer rather than hiding the problem with a hem addition.