COMPARISON OF INSTRUMENTAL METHODS FOR ASSESSING COLOR FASTNESS .1. CHANGE IN COLOR

Different instrumental methods for assessing change in colour are desc ribed. A set of experimental results were used to test the performance of the various formulae and to illustrate the lack of agreement betwe en them and visual results. Each method is based on a different colour -difference formulae. The differences between the formulae are illustr ated by plotting constant Delta E contours for each of the formulae fo r various colour centres. The areas of colour where the formulae diffe r most from each other have been identified. The differences between t he methods in some areas were very large, up to a factor of five in te rms of Delta E, or two full grades of fastness.