A 2/60s Warp Label and a Trader's 'Same Count' Claim
A handloom cooperative in Chennimalai has a warp beam marked “2/60s cotton, 2,400 ends, 100 m” and a weft supply of 40s cotton. The weave plan is 60 ends/inch in the warp and 48 picks/inch in the weft, 40 inches wide on the loom. A trader offers 20 tex polyester yarn at a lower price and claims it is “the same count” as the warp. The cooperative currently uses the same twist multiplier of 3.5 for both warp and weft; the weaver reports frequent warp breaks and a slightly hairy warp. Warp waste is 5% and weft waste is 8%. The current warp costs ₹420/kg and the weft costs ₹390/kg. The cooperative must quote for 100 m of fabric and needs to know whether the trader's claim is safe to accept.
1. Convert the warp and weft counts into tex, and calculate the warp and weft yarn weights needed for 100 m of fabric, including the stated waste.
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Use tex = 590.5 ÷ Ne. The warp is 2/60s, meaning two 60s singles plied; the resultant count is 60 ÷ 2 = 30s Ne. Therefore warp tex = 590.5 ÷ 30 = 19.68 tex. The weft is 40s Ne, so weft tex = 590.5 ÷ 40 = 14.76 tex.
Warp: 2,400 ends × 100 m × 19.68 g/1,000 m = 4,723 g = 4.72 kg. With 5% waste, buy 4.72 × 1.05 = 4.96 kg.
Weft: picks per metre = 48 × 39.37 = 1,890 picks/m. Weft length per pick = 40 inches = 1.016 m. Mass per metre of fabric = 1,890 × 1.016 × 14.76 ÷ 1,000 = 28.34 g/m. For 100 m = 2.834 kg; with 8% waste = 3.06 kg.
So the quote needs about 4.96 kg warp and 3.06 kg weft. The 20 tex polyester is close to 19.68 tex, but count equivalence is not the same as performance equivalence.
2. Evaluate the trader's claim that 20 tex polyester is “the same count” as 2/60s cotton. Should the cooperative use it for the warp? Give reasons based on fibre properties and the reported warp breaks.
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The claim is numerically almost correct: 20 tex is within about 1.6% of 19.68 tex, so the linear density is similar. But count is only one variable. Polyester is stronger, more abrasion-resistant and more extensible than cotton, so it could reduce warp breaks. It is also thermoplastic and less moisture-absorbent, which changes sizing, heat-setting, static behaviour and comfort. A polyester warp may give a leaner, less absorbent fabric and could change cover because polyester density differs from cotton.
The immediate break problem is more likely caused by insufficient warp twist. With a twist multiplier of 3.5, TPI = 3.5 × √60 = 27.1 for the 60s singles; at 4.2 it would be 32.5. Warp needs higher twist than weft for abrasion resistance, so the cooperative should raise the warp TM to about 4.2 while keeping the weft near 3.2 (TPI = 3.2 × √40 = 20.2). For a plied yarn, the ply twist should be balanced against the singles twist.
Recommendation: first correct the warp twist and loom tension. Accept 20 tex polyester only if the buyer accepts a blend or synthetic warp and the savings cover re-setting, heat-setting and any comfort loss.
3. Compute the yarn cost for 100 m of fabric using the current yarns, and state one condition under which the cheaper 20 tex polyester warp would still be rejected.
Read the worked answer
Warp cost = 4.96 kg × ₹420/kg = ₹2,083.20. Weft cost = 3.06 kg × ₹390/kg = ₹1,193.40. Total yarn cost = ₹2,083.20 + ₹1,193.40 = ₹3,276.60 for 100 m, before dyeing, sizing and weaving charges.
The polyester offer may lower the yarn bill, but it should still be rejected if the buyer's contract specifies 100% cotton or requires high moisture absorbency, non-thermoplastic behaviour, or a particular hand and drape. It should also be rejected if the price saving does not cover the cost of changing sizing, loom settings and heat-setting, or if the polyester warp would alter the fabric cover and shade acceptance. In a hot-weather market, the comfort claim of cotton can be worth more than a small yarn saving. The decision should be made on the whole fabric cost and the buyer's specification, not on the count alone.