BIOCLEANING

Cleaning is one of the first and most important steps in conservative restora- tion intervention, as it removes the unwanted layers of dirt and deposit from the surface of an artefact. It must be done selectively, however, by adapting the cleaning operation to the different zones and removing successive layers of deposit without acting directly on the original materials of the surface. Generally, cleaning protocols are based on chemical or physical procedures with potential negative effects for restorers’ health and/or for the materials constituting the artworks. As an alternative, solvent gels, rigid gels and resin soaps can be used for selective cleaning. In recent decades, biological clean- ing has greatly improved as a result of research into biotechnologies and today plays an important role in the preservation and restoration of cultural assets. Nowadays, biocleaning by viable bacterial cells or hydrolytic enzymes represents a resource with great potential in the restoration of cultural heri- tage, minimising risks for artworks and for human health. New methodologies based on sulphate-reducing bacteria or bioactive molecules with hydrolytic activity have been applied as selective and safer cleaning methods in the removal of black crusts from stone surfaces or organic materials such as glue and/or adhesives, from paintings and other substrates.