AN FTIR-BASED EXPLORATION OF THE EFFECTS OF WET CLEANING TREATMENTS ON ARTISTS’ ACRYLIC EMULSION PAINT FILMS

Understanding changes to acrylic emulsion paint films duringwet surface cleaning treatments is a priority for conservatorsof modern painted surfaces. To explore the presence,extraction and removal of soluble components fromacrylic paint films, contemporar y paint samples and worksof art were examined using several FTIR-based techniquesincluding: transmission microscopy, attenuated totalreflectance (ATR) and in-situ non-invasive mid-IRreflectance spectroscopy. The major constituents identifiedon paint surfaces and extracted from bulk films werenon-ionic polyethoxylate (PEO) type surfactants used asdispersing agents and emulsion stabilisers. The identificationof other extracted constituents was hampered by lowconcentrations and the proprietar y nature of many additives.Surface surfactant was removed within five to twentyseconds by aqueous swabbing treatment, by acceleratedlight ageing, and was relatively unaffected by aliphatic solvents.Monitoring of contemporar y paint films after aqueouscleaning treatment confirms that surfactant continuesto migrate to the surface. The analysis of contemporar ypaint films suggests surface surfactant abundance is primarilyinfluenced by brand. Combined results from the insituanalysis of five paintings dating between 1962 and1973 confirmed the presence of surfactant on some paintlayers and not others.