Investigating the Effects of Atomic Oxygen Cold Plasma Surface Cleaning on the Oil Paint

Surface cleaning plays a crucial role in the conservation of cultural heritage objects. Existing methods still present limitations in terms of efficacy, safety, and sustainability, pushing the field for constant innovation. This study investigates a novel cleaning technique based on the use of atomic oxygen (AO) generated in atmospheric pressure plasma. The focus is placed on the systematic investigation of the impact of AO on sensitive organic substrates during the cleaning action, to explore the applicability and limitations of the technique. To this aim, the experimentation is carried out on model oil paint layers, as natural curing and aging mechanisms of polyunsaturated oils are driven and defined by interactions with atmospheric molecular oxygen. Optical microscopy, SEM, ATR-FTIR, SPME/GC-MS, and EGA-MS are used, showing that treated fresh oil paint layers undergo an increase in oxidative degradation and chain scission, while crosslinking is favored in aged paint layers. Over time, AO-treated samples evolve to closely resemble control samples.