a) Basic Scale for Assessing Change in Colour
A scale that consists of five pairs of non-glossy grey-coloured chips, and in which a fastness rating of 5 (indicating no colour change) at one end of the scale is represented by two identical grey chips, and a fastness rating of 1 (indicating a severe colour change) at the other end of the scale is represented by a pair of grey chips having a colour difference of 13,6 Cielab units.
b) Basic Scale for Assessing Staining
A scale that consists of one pair of white and four pairs of non-glossy grey- and white-coloured chips, and in which a fastness rating of 5 (indicating severe staining) at one end of the scale is represented by the pair of white chips, and a fastness rating of 1 (indicating severe staining) at the other end of the scale is represented by a pair of chips having a colour difference of 34,1 Cielab units.
NOTE:
Both scales may be augmented to form a 9-step scale by the provision of similar chips that illustrate the perceived colour differences corresponding to the half-step fastness ratings.