A random selection of 52 commercially prepared artists' varnishes and media from 11 different makers was analyzed by Fourier transform infrared spectroscopy. The compositions determined by this analysis are tabulated. The results are discussed in extensive notes to the table which refer to reports in the conservation literature on the use, testing, and observation of artificially and naturally aged materials of identical or similar composition used in artistic or conservation applications. The stability or longevity of these products can be inferred from these comparisons.