Cover: AI-generated conceptual illustration for WEFTSIGNAL, not documentary photography.
Three different things get called the standard
A colour approval file usually holds three objects that look alike and mean different things: the physical standard the shade was set against, the lab dip submitted against it, and the bulk dye lot that arrived later. They were produced at different times, on different equipment, in different quantities. When a dispute starts, the first useful question is which of the three someone is holding.
What a lab dip is, and what it is not
CottonWorks, the textile education platform published by Cotton Incorporated, describes lab dipping as the first step in developing and approving a product’s colour, beginning with the brand’s request for a lab dip in a specified colour and substrate. It notes that the sample is dyed in a machine replicating the full-scale production procedure, though adjustments may be made when the formula is scaled up, then washed to remove unfixed dye and conditioned to standard humidity and temperature before measurement against the standard’s master spectral data. A lab dip is evidence about a formula on one substrate — not a prediction of a bulk lot.
A standard is a physical object, and physical objects age
This is why the electronic record matters. A physical standard is handled, shipped and stored; its surface changes slowly and unevenly, and the change is invisible to the people who work with it daily. The ISO catalogue entry for ISO 105-A02:1993, the grey scale used for assessing change in colour in colour fastness tests, states that a precise colorimetric specification of the scale is given as a permanent record against which newly prepared working standards, and standards that may have changed, can be compared. The same logic applies to a shade standard: without a spectral record there is nothing to compare an aged standard against.
Measurement happens under conditions, not in the abstract
ISO 105-J01:1997, which covers general principles for the measurement of surface colour, exists because instrumental colour measurement is only reproducible when the conditions around it are controlled and stated. Conditioning, the instrument, the aperture, the number of readings and how they are combined all belong to the result. An approval that records a colour difference without recording the conditions has recorded a number, not a decision.
Illuminant and metamerism: why a match can change its mind
Two samples can agree under one light source and disagree under another. That is metamerism, and it arises because different colourant combinations can produce the same apparent colour by different spectral routes. Change the light, and the two routes diverge. A colour decision made under an unnamed light is therefore a decision that cannot be reproduced, and the requirement is to name the illuminant — and, where the end use exposes the product to more than one, to say whether the match must hold under more than one.
What “approved” leaves out
The word approved, on its own, is the weakest item in most colour files. It says a decision was made, but not against what, under what light, or with what freedom to differ — the parts that get renegotiated when a bulk lot arrives, usually by people who were not in the room.
An illustrative example, not a recommendation
Suppose, illustratively, a lab dip is approved in a supplier’s office under a viewing cabinet, and no record names the light source. The bulk lot is dyed to the same formula on a different substrate lot, inspected under the same cabinet, and passes. Months later a buyer views the garment in daylight and sees a difference that was present all along. Nothing in the file is wrong; it simply did not record the one condition under which the match holds. The example is hypothetical, the control is not.
What a colour approval record should capture
What is written at approval is what makes the decision legible later, once the people who agreed it have moved on.
- Standard: the physical standard’s identity, and its spectral record.
- Substrate: fabric, construction and finishing route the dip was made on.
- Illuminant: the light source under which the match was judged.
- Method: the measuring conditions, named by designation.
- Basis: whether the requirement applies to one reading, a mean or every specimen.
- Iterations: revisions made, so the approved version is identifiable.
- Change control: who re-approves when substrate, colourants or dyehouse change.
Where this sits in the approval chain
Colour is one requirement among several settled before bulk, and it is rarely settled alone. Our pre-production approval explainer covers the wider gate, and the fabric specification checklist covers how a measurable property is written down so that it can be checked. A shade approved against an unnamed substrate or an unnamed light has been approved against nothing in particular.
Source and further reading
Sources consulted 16 October 2026: ISO — ISO 105-A02:1993, Textiles: tests for colour fastness, Part A02: grey scale for assessing change in colour; ISO — ISO 105-J01:1997, Textiles: tests for colour fastness, Part J01: general principles for measurement of surface colour; CottonWorks — Lab Dip Process. Cited by designation and catalogue page only. The framework, checklist and illustrative example in this explainer are WEFTSIGNAL editorial material, not requirements issued by those organisations.
Continue exploring textile industry coverage and our editorial standards.
