Numeric Standard
Colour variance measurement defines the acceptable deviation between a dye batch and the target standard using three-dimensional coordinates. In digital colour matching, colorimetric tolerance is set as a maximum sphere of acceptability around the standard point. The laboratory uses a spectrophotometer to measure the delta-E value of the dyed fabric.
This value must fall within the defined boundary to be accepted.
Factory Limits
Industrial production requires larger acceptability boundaries than laboratory samples due to dyeing machine variations. While a brand might set a colorimetric tolerance of zero point five delta-E for development samples, the bulk production limits are often wider to accommodate unavoidable process drift. If the tolerance is too tight, the mill will reject many batches and have to re-dye the fabric, which damages the fibres and wastes water.
Light Source
Visual inspection remains a backup to numeric limits but must be carried out under standard illumination. Fabric rolls that meet the colorimetric tolerance under one light source can fail under another. The spectrophotometer calculates the deviation under multiple illuminants to ensure consistency.
This minimizes color disputes between the brand and the mill.
Pass Fail
Quality managers use automated software to decide whether a batch can be shipped. If the sample falls within the colorimetric tolerance, it is automatically passed. This makes color approval fast and objective.
