COMPARISON OF INSTRUMENTAL METHODS FOR ASSESSING COLOUR FASTNESS. PART 1 -CHANGE IN COLOUR

Different instrumental methods for assessing change in colour are described. A set of experimental results were used to test the performance of the various formulae and to illustrate the lack of agreement between them and visual results. Each method is based on a different colour-difference formulae. The differences between the formulae are illustrated by plotting constant AE contours for each of the formulae for various colour centres. The areas of colour where the formulae differ most from each other have been identified. The differences between the methods in some areas were very large, up to a factor of five in terms of ΔE, or two full grades of fastness.