The Hospital Sheeting That Shrank Past Spec
A weaving unit in Nagaon wins a hospital tender for 10,000 m of bleached cotton sheeting. The tender specifies, on the finished fabric: 40s x 40s, 100 ends/inch, 60 picks/inch, 56 in width, about 120 g/m2, and residual shrinkage not more than 5% after three standard domestic washes. The unit weaves grey at 63.0 in with 90 ends/inch and 54 picks/inch at 98 g/m2, and sends the whole 10,000 m to a processor for desizing, scouring and bleaching. The processor returns the roll at 57.5 in width, 98.6 ends/inch, 56 picks/inch and 112 g/m2, stentered and dried under warp tension. A pre-shipment wash test on three samples gives 54.5 in width and 58.3 picks/inch, with a further 4% loss in length. The buyer's inspector rejects the lot as undersized, overweight and over-ended. The processor says the loomstate was "already like that", and the unit has already received 60% of the contract value.
1. Using the numbers, explain what happens to the fabric between loom, processor and wash, and identify the two decisions that produced the rejection.
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Width. Grey 63.0 in to processed 57.5 in is an 8.7% contraction - partly normal crimp interchange and relaxation, partly the processor stentering to a width chosen by the processor rather than derived from the tender. The first domestic wash then takes 57.5 in to 54.5 in, another 5.2%, which alone breaks the 5% limit. Measured from loomstate, the total is 63.0 to 54.5 in, a 13.5% width loss.
Ends and mass. Ends/inch rise as the cloth contracts: 90 x (63.0/54.5) = 104 ends/inch, 4% above the 100 specified. Area density follows the same logic. The washing step shrinks length about 7.4% from loomstate (3.6% at processing plus 4% at wash), so mass per square metre becomes roughly 98 x (63.0/54.5) x (1/0.926) = about 122 g/m2 against 120 specified - the unit has effectively given away several percent of yarn mass on 10,000 m.
The two decisions. First, the grey construction was set to look correct on the loom, with no allowance for what happens in finishing and washing. Second, the processor was allowed to deliver stentered, tension-dried cloth with no mechanical compressive shrinkage and no guaranteed residual-shrinkage figure. Latent shrinkage from stentering is released in the buyer's first wash, and the unit carries the cost.
2. Recalculate the grey construction needed to meet the tender, and state what you would now require from the processor.
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Use the observed loomstate-to-washed factors. Width factor = 63.0/54.5 = 1.156. Length factor = 1/0.926 = 1.080. Area factor = 1.156 x 1.080 = 1.248.
Targets on the washed fabric: 56.0 in, 100 ends/inch, 120 g/m2.
- Grey width = 56.0 x 1.156 = 64.7 in (weave 64.5–65 in).
- Grey ends/inch = 100 / 1.156 = 86.5, so 86–87 ends/inch.
- Total ends on the loom = 64.7 x 86.5 = about 5,600 ends - check the reed and healds can carry this, since the earlier set was 63 x 90 = 5,670 ends, so the same reed width is broadly workable.
- Grey GSM = 120 / 1.248 = 96 g/m2.
What to require from the processor. A written residual-shrinkage guarantee (not more than 5% by the tender's wash method), achieved by compressive shrinkage/compacting rather than by stentering alone; delivery width and ends/inch stated with tolerances; length and width shrinkage test results supplied per lot; and rejection, rework and freight at the processor's cost if the guarantee fails. Pay the balance only on approval of the test report, and wash-test three samples from each finished lot before dispatch.
3. The unit wants to ship the rejected 10,000 m as it is, at a reduced rate. Evaluate this option against remaking, on the evidence you have.
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What the buyer would actually get. A cloth 1.5 in narrow, about 4% over-ended and roughly 2 g/m2 heavy, with 5.2% width shrinkage and about 7.4% length shrinkage on first wash. For hospital sheeting that is cut and sewn into flat sheets and drawsheets, the length shrinkage matters more than the width: a sheet cut to a nominal size will not fit the mattress after the hospital's first boil wash.
Discount option. A reduced rate only works if the buyer re-specifies the fabric in writing - narrower width, declared shrinkage - and if the price cut covers the extra metres the hospital will need per sheet plus the sewing and replacement cost. That is unlikely at a 5% shrinkage level, and a government tender usually cannot be varied after inspection without a fresh sanction.
Remake option. Recutting to 64.7 in grey with 86.5 ends/inch means re-reeding, which is a few hours of loom work, not a new warp - the 60% already received is not lost. The cheaper route is usually: negotiate a written deviation on the existing lot for non-critical uses (underpads, trolley covers), and remake the balance to the corrected construction with the processor's shrinkage guarantee attached.
Decision rule. Compare the discount needed to make the lot acceptable per metre against the re-reeding and processing cost per metre; with 10,000 m and a live tender, remake is normally the lower-risk choice.