Knit Garment Shrinkage After a Pre-Shrunk Fabric Claim
A garment manufacturer buys 100% cotton single jersey, 160 g/m2, 30s combed, tubular, for a 50,000-piece order. The customer requires after three home launderings at 40 C: length shrinkage no more than -5.0% and width no more than -4.0%. Current finished-fabric test results are length -7.5% and width -2.0%. The in-house compactor can compact up to 6% length but gains about 1.5% width for every 2% length compaction; the stenter can remove width but adds cost and may affect hand. The current marker uses 0% length and width allowance because the knitter sold the fabric as pre-shrunk. Fabric is tubular, 68 cm laid width, and the knitter reports 5% spirality. The order ships in 10 days; 8,000 garments have already been cut using the current marker, and fabric for the remainder is in greige. The customer has rejected a previous lot for excessive length shrinkage and is unlikely to accept a concession.
1. Calculate the compaction needed to bring length shrinkage within tolerance, allowing a safety margin. Assess whether the compactor can achieve it and what will happen to width.
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The minimum compaction is found from the ratio of the allowed residual shrinkage to the current shrinkage: Required compaction = 1 - (1 - 0.05)/(1 - 0.075) = 1 - 0.95/0.925 = 1 - 1.027 = 2.7%. Add a 0.8% safety margin for lot and wash variation, so target 3.5% length compaction. The compactor can reach 6%, so the length target is feasible.
Width effect: the compactor gains about 1.5% width for every 2% length compaction, or 0.75% width per 1% compaction. At 3.5% compaction, width gain is about 2.6%. The current width shrinkage is -2.0%, so after compaction and washing the width would move to about +0.6% (growth). That is normally acceptable if the customer's width tolerance is only a shrinkage limit, but the actual garment width must be checked. If width growth is unacceptable, a light stenter correction can remove width, but it adds cost and may reduce bulk and hand.
2. Propose a finishing and cut plan for the remaining 42,000 garments, including test protocol and allowance policy. Explain how you would handle spirality.
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Finish the greige fabric in a controlled compaction range of 3.0-4.0%, not at the maximum 6%, to preserve hand and limit width growth. After compaction, condition and relax the fabric for at least 24 hours before cutting. Use a marker with 0% length allowance because the shrinkage is now built into the fabric, but add a 1% length buffer only if the first production lot shows variability. For width, cut to the measured compacted width; if width growth exceeds the pattern limit, stenter-correct only that lot.
Test protocol: take five specimens from each lot, wash three times at 40 C, dry as the customer specifies, and measure length and width after each wash. Acceptance: length -3.5% to -5.0%, width -2.0% to +1.0%, no edge curl, and spirality no more than 3%. Spirality at 5% is a separate risk; control it by requesting low-twist or balanced yarn, or by cutting with a compensatory offset. Do not rely on washing to remove spirality after cutting.
3. Decide what to do with the 8,000 garments already cut with 0% allowance. Recommend whether to recut, rework, or ship with a concession, and give the commercial reasoning.
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Do not ship the 8,000 cut garments. With 0% allowance and -7.5% length shrinkage, they will be short by about 2.5 percentage points beyond the -5.0% limit after washing. The customer has already rejected a previous lot for the same issue, so a concession is unlikely and would damage the relationship.
Recut replacements from compacted fabric. Use the already-cut panels only if they can be converted into a shorter style approved by the customer, or sell them as seconds through a separate channel. Rework by garment washing is not reliable because the panels are already cut and the shrinkage is not uniform; it also risks further width and spirality changes. The commercial rule is: compare the cost of recutting 8,000 pieces with the cost of a rejected shipment, air freight, and lost future orders. Recutting is the lower-risk decision. Inform the customer only if the recut affects the ship date; otherwise replace the panels and protect the delivery.