An analytical and applicative approach to the cleaning of artworks

Cleaning is a critical operation aimed to recovering the legibility of the artwork (1963, C. Brandi, Theory of restoration), and it may involve, depending on the instances, removing soiling materials from surfaces (surface cleaning) or thinning/removing altered or unwanted layers (discoloured varnishes, overpaints, patinas,etc..). It should be performed in the most selectively possible way, minimizing the risk of altering the chemical-physical and morphological properties of the surfaces to be preserved. Aims of the present research were to develop and to evaluate specific materials and selective methodologies for the surface cleaning of plaster and wax artworks. Another purpose was to investigate the risk associated with the exposure of egg yolk-based tempera films to water and organic solvents during cleaning. In collaboration with several Institutions, relying on the indispensable collaboration of various conservators/restorers, an analytical and applicative research was conducted on both mocks up and actual artworks or their fragments. This research allowed to develop an effective and innovative method for cleaning plaster by using Agarose-based gelling materials, to prove the suitability of specifically designed aqueous solutions for cleaning wax artworks, and to evaluate the behaviour and the effects of water and organic solvents on unaged egg tempera films and on a 16th century actual panel painting, yielding information on physical phenomena such as visual changes and swelling/leaching processes at various solvent polarities.