A study of the yellowing/bleaching characteristics of two commercial paints (linseed oil and linseed alkyd paints -- compositions supplied) and three experimental paints (based on alkali or decolorized linseed oil or the pure triglycende trilinolenin) during sequential exposure to dark and light. The degree of yellowing is measured by reflectance spectrophotometry using a Beckman DB instrument. Graphs are presented for the text samples of yellowness index versus time for a series of cycles of exposure to light and darkness. The linseed oil paints were found to yellow less and more slowly with each cycle. Linseed oil alkyds, however, yellowed at about the same rate and to the same extent through each cycle. -- AATA