Rolls from the same dye lot can still differ in shade, because continuous dyeing and finishing drift over the length of a run and because rolls from different batches are sometimes grouped under one lot number. You avoid it by fixing the approved standard early, asking for one dye lot per order where possible, having every roll measured against the standard, and accepting only rolls grouped within a tolerance you have agreed. The point is to catch variation at the mill, not on your cutting table.
Shade variation within a delivery is the most common complaint on woven fabric from India. It is expensive because a garment cut from two rolls of slightly different shade is a reject, even though each roll is a perfectly good fabric on its own.
Where roll-to-roll variation comes from
- Drift in a continuous dye range as chemical concentrations, speed or temperature change over a long run.
- Different jigger or jet batches combined under one lot number.
- Finishing differences, since a resin or softener finish can shift the shade of fabric that was dyed together.
- Centre-to-selvedge variation on wide fabric, which appears as a shade difference between rolls once pieces are cut.
- Different greige lots behind the dye lot, which take up dye differently.
Controls to agree before dyeing
Approve a lab dip and, for a larger order, a bulk strike-off or pilot roll, and keep a sealed piece of the approved standard at the mill, at your office and with your inspector. Ask the mill to dye the full order quantity in one lot if the machine capacity allows, and to tell you in advance if it cannot. Agree a tolerance, usually expressed as a Delta E value measured on a spectrophotometer under an agreed illuminant, along with a visual check in a light cabinet.
Controls at the end of the run
Every roll should be read on the spectrophotometer against the standard, and the readings should be recorded on the packing list or a shade report. Rolls that fall inside the tolerance are grouped into shade bands and labelled so that your cutting room can keep one band per garment. Rolls outside the tolerance should be held back and either redyed, sold elsewhere or shipped only with your written agreement.
Ask for roll-to-roll continuity cards, small swatches cut from the end of each roll and mounted in sequence, so you can see the drift for yourself before the goods leave. For yarn-dyed fabrics the same logic applies to the yarn lots rather than the fabric dye lot.
How we keep shade in check
We visit the mill during dyeing, collect the shade report and continuity cards, and inspect rolls before loading with your sealed standard in hand. Where readings look inconsistent, we send cuttings from sampled rolls to an NABL-accredited lab for an independent check. For a quick look at your current shade controls, we offer a free 20-minute sourcing review.