The Effects of Aqueous Washing and Bleaching Treatments on Cotton Duck Canvas

This study investigates whole-object cleaning treatments for paintings having large areas of bare cotton canvas. It evaluates short- and long-term impact of various aqueous washing/bleaching treatments on fabric color and tensile strength. Material forming the subject of the testing was cotton duck from the studio of artist Morris Louis; it was artificially aged by exposure to elevated temperature. Immediate effects of treatments were monitored, as were consequences of further post-treatment accelerated ageing. Post-treatment ageing assessed impact of treatments on long-term stability. Color measurements, specifically lightness differences ΔL*, served as indicators of appearance change caused by ageing-derived discoloration and the treatments. Corresponding changes in fabric strength were measured by instrumental tensile testing done on individual warp and weft yarns separated from the various test samples. Large numbers of yarns of each specimen condition were tested for tensile strength. Statistical analysis was conducted on the sets of tensile strength data to determine significance of differences in mean tensile strength values. Study results may inform understanding of possible outcomes—short and long term—of washing/bleaching treatments on paintings showing large areas of discolored, bare cotton canvas. Findings may guide choice of treatment and treatment parameters according to the needs of object under consideration.