The surest way to avoid shade variation between production lots is to dye the whole order in one lot where possible, and to control everything else in writing when it is not. Shade differences come from different dye lots, different greige, different machines and different operators, and the mill will not control these for you unless the contract tells it to. The tools are familiar to any competent dye house: lab dip approval under a named light source, a retained standard, shade bands, roll grouping and a numerical tolerance. The buyer's job is to ask for all of them and to check the evidence.
Variation shows up in three forms. Lot to lot, where the first delivery and the repeat do not match. Roll to roll inside one lot, which is a problem on the cutting table. And within the roll, as centre to selvedge difference or tailing from the start to the end of a batch. Each needs a slightly different control.
Controls to put in the contract
- Lab dip approval under an agreed light source, usually D65 daylight plus a store light such as TL84, with a check for metamerism between them.
- A sealed approved standard, countersigned by both sides, with one set held by you and one by the mill.
- A written tolerance, either a delta E limit under a named formula such as CMC 2:1, typically below 1.0 against the standard, or a grey scale rating of 4 or better for colour change.
- One dye lot per colour per order where quantities allow. If several lots are unavoidable, each lot must be measured against the standard and the results shared before finishing.
- Shade bands or a shade continuity card for every lot, with swatches cut from the start, middle and end of the batch.
- Roll grouping, so that rolls within one shade group are packed and labelled together and your cutting room never mixes groups within a garment.
- Lot-wise testing of colour fastness to washing, rubbing and light, since a shade that passes visually can still fail in use.
What the mill should be doing
Ask how the dye house manages greige. Consistent shade starts with consistent fibre and preparation, so a mill that switches cotton sources mid-order or runs RFD (ready for dyeing) fabric through different bleaching recipes will struggle to match. Ask whether they use a spectrophotometer and a recipe management system, or match by eye. Continuous dyeing ranges usually give better consistency than jigger or jet batches for long runs of solid shades.
Insist on seeing shade continuity cards before you approve shipment, not after. Many disputes end with a mill saying the rolls were within tolerance and the buyer saying they were not, with no shared record of what was measured. A card with measured delta E values against the retained standard settles it.
What to do on your side
Keep the retained standard in the dark and at room temperature, and replace it on repeat orders if it has aged. Sequence your purchase orders so that colours recur in one bulk lot rather than small repeats, which force new lots. Brief your cutting room to work within shade groups. And when you place a repeat, send the mill the lot number and the standard reference, not just the colour name.
How we help
We attend lab dip and bulk approval at the mill, cut sealed swatches from each lot and send them to an NABL-accredited lab for delta E and fastness testing against your retained standard. Shade continuity cards are checked before loading, and the roll grouping is verified against the packing list during loading supervision. A free 20-minute sourcing review covers how to write the tolerance into your next contract.