The use of The Society of Dyers and Colourists' Grey Scale, British Standard 2662: 1961, is described. The scale is a set of five pairs of color conitrast chips. Standard contrasts of 1 through 5 are equivalent to 12, 6, 3, 11/2 and 0 NBS units of color difference, respectively. The extent of fading of British Standard 1006: 1961 blue cloths on the walls of a daylighted gallery was studied by visual comparison with the standard grey scale over a period of seven years. The results are preseiited graphically; the precision of such visual reading is approximately ± 0.4 scale units. British Standard 1006: 1961 blue cloths are recommenided for use as fading standards, and two references concerning the influence of temperature, humidity and light types on the fading rate of this material are cited.