Evaluating cleaning systems for use on water sensitive modern oil paints: a comparative study

This paper outlines the approach and key findings of systematic studies into the use of various surface cleaning materials on a range of accelerated-aged sensitive oil paint surfaces, carried out through the Cleaning Modern Oil Paints (CMOP) project. Studies involved the use of recently introduced options such as adjusted pH and conductivity waters, spreadable gels, rigid gels, silicone emulsifiers, and mineral spirits-based microemulsions, with additional explorations into the effects of application methods. The evaluation methodology encompassed star diagrams designed to capture observations made during cleaning tests, and paint surface evaluations using digital microscopy, colour and gloss assessment, and ATR-FTIR analysis. In most cases, the most promising free solvents were subsequently incorporated into spreadable and rigid gels, water-in-oil microemulsions and silicone emulsions, tailoring the approach to further minimise undesirable effects where possible. Cleaning system residues were also investigated using visual inspection, microscopy and ATR-FTIR analysis, with a selection of samples further investigated using a pyrolysis on-line micro-reaction sampler and XPS analysis. The combined results offer information on the advantages and risks associated with each cleaning material, and an approach to optimising wet systems for the cleaning of sensitive oil painted surfaces.