Blend Claim on a Handloom Yarn Lot
A handloom cooperative in Karur bought 500 kg of open-end yarn at ₹210/kg, invoiced as 65/35 polyester-cotton. Members complain that the yarn feels harsh, generates static on the warping creel, and takes dye unevenly in their soft-flow machines. A 5.000 g sample was tested in the co-op's small lab. In 70% sulphuric acid at 25°C, 1.40 g dissolved and 3.60 g remained. Oven-dry moisture regain was 2.8%. A burn test left a hard black bead and gave a faint chemical odour; the flame did not continue to burn after removal. The supplier's invoice states a tolerance of ±3% on blend components. Cotton in the local market is ₹160/kg and polyester staple fibre is ₹95/kg; yarn conversion and overheads are estimated at ₹80/kg. The co-op has already woven 120 m of fabric from the lot and has another 300 kg in store. They want to know whether to reject the lot, negotiate a price cut, or use it for a different product.
1. Using the solubility and moisture-regain results, estimate the blend ratio and decide whether the lot meets the ±3% tolerance. Show the calculation.
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70% sulphuric acid at room temperature dissolves cotton but leaves normal polyester substantially undissolved. Therefore:
- Cotton = 1.40 g / 5.00 g × 100 = 28.0%
- Polyester = 3.60 g / 5.00 g × 100 = 72.0%
The invoice says 65/35 polyester-cotton, i.e. 65% polyester and 35% cotton. The measured polyester content is 72%, a deviation of +7 percentage points, which is outside the stated ±3% tolerance. The moisture-regain result supports this: expected regain for 65/35 is (0.65 × 0.4) + (0.35 × 8.5) = 3.24%, while 72/28 would be about 2.67%. The measured 2.8% is much closer to the higher-polyester blend. The burn test only confirms that a synthetic fibre is present; the hard black bead is characteristic of polyester, but it cannot quantify the ratio. Conclusion: the lot does not meet the invoiced composition.
2. Explain why the observed static and uneven dyeing are consistent with the tested composition, and state one risk of using the lot for the intended handloom fabric.
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Polyester is hydrophobic and has very low moisture regain, so a blend richer in polyester than claimed will generate more static, especially during dry warping and weaving. It also feels harsher and less absorbent than a normal 65/35 blend. Dyeing behaviour is the stronger clue: cotton is normally dyed with reactive dyes and polyester with disperse dyes. If the co-op's recipe assumes 65/35 and uses only a reactive dye, the extra polyester will remain largely undyed, giving a pale, heather-like or uneven shade. If a two-dye recipe is used, the shade will still shift because the actual blend is 72/28 rather than 65/35. A practical risk is that the woven fabric will not match the approved handle, absorbency or union shade, and may be rejected by the buyer. The lot is safer for dark shades where the polyester can be dyed with a disperse dye and the cotton with a reactive dye, but only after a fresh shade recipe is established.
3. Calculate the fair fibre value per kg of the actual blend and of the invoiced blend, and recommend a negotiating position for the 300 kg remaining. Include conversion cost.
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Fibre value of the invoiced 65/35 blend: (0.65 × ₹95) + (0.35 × ₹160) = ₹61.75 + ₹56.00 = ₹117.75/kg. Add ₹80/kg conversion: ₹197.75/kg.
Fibre value of the tested 72/28 blend: (0.72 × ₹95) + (0.28 × ₹160) = ₹68.40 + ₹44.80 = ₹113.20/kg. Add ₹80/kg conversion: ₹193.20/kg.
The blend claim is worth ₹117.75 − ₹113.20 = ₹4.55/kg less than invoiced. On the 300 kg remaining, that is ₹4.55 × 300 = ₹1,365. On the whole 500 kg lot it is ₹2,275. Note that the invoice price of ₹210/kg is above even the fair value of the claimed blend (₹197.75/kg), so the ₹4.55/kg figure is the blend-related claim, not the whole commercial margin. Recommendation: document the test, ask for a replacement at the correct blend or a price credit of about ₹4.55/kg on the remaining 300 kg, and seek compensation on the 200 kg already used. Do not use the remaining yarn for pale or union shades until a dyeing trial proves the recipe.