The removal of aged acrylic coatings from wall paintings using microemulsions

This paper describes experiments designed to remove aged acrylic coatings, such as Paraloid B-72, from lime-based wall paintings using poultices loaded with microemulsions. In the first step, four surfactant-based microemulsions were tested on 60 specimens imitating Paraloid-consolidated wall paintings to determine which was most effective. In the second step, the best formulation was fine-tuned and tested on six specimens. Among improvements was the replacement of the original surfactant with one that naturally degraded and produced minimal lathering. Successful removal of Paraloid (determined by raking and UV light examination, FTIR analysis and contact angle measurements) was marred by contamination of the specimen by residual cellulose powder (from the poultice), detected with iodine vapour staining. The third experiment was designed to eliminate this contamination. A microemulsion-loaded hydrogel was successfully tested on four specimens. Results indicate that it is possible to extract Paraloid B-72 from wall paintings without contamination.