The characteristics of the spectral reflectance curves of colored substances can be used in qualitative and quantitative analysis. The method is non-destructive. The absorption bands in the usual curve are not as numerous as those in the typical infrared spectral analysis, but the technique of differential spectral curve analysis, the analysis of the difference between two absorption curves, can provide considerable precision to the interpretation. There are now available computers, such as the Davidson and Hemmendinger Comic, which greatly facilitate the analysis of curves. (Davidson, H. R.; Hemmendinger, H., and Landry, J. L. R., Jr., J. Soc. Dyers Colourists, 79 (1963), pp. 577-589). The authors suggest the use of the method in the analysis of pigments, in studies of fading, and in the verification, during the removal of varnishes, of the presence or absence of glazes.