18 – Corrosion inhibitors for metallic artefacts: temporary protection

Publisher Summary This chapter states that environment is the main cause of decay of metallic elements from cultural heritage. Art curators with the support of analytical science attempt to intervene to stop the deterioration. In many cases, the conservation efforts cannot stop the deterioration process or reverse the ensuing damage, but they can help slow the rate of degradation to ensure a longer existence for artefacts. The interactions between the metal and its environment are responsible for the electrochemical reactions leading to corrosion. To avoid further degradation and in general the appearance of corrosion products, a more or less insulating barrier must be created on the metallic surface between the object and the atmosphere. Different barrier coatings have been developed, such as anodic oxides, ceramic and inorganic coatings as corrosion inhibitors, organic coatings, and conversion coatings. Most of them were first developed for industrial applications. They generally require the removal of the corrosion products and their application leads to important changes in the visual appearance of the metallic surface. These treatments have also been applied for the outdoor protection of large structures that are a part of the cultural heritage, such as bridges or buildings protected by the French legislation. However, for a large proportion of works belonging to the cultural heritage, such as patinated artefacts or sculptures and archaeological artefacts, these protection systems cannot be applied. The chapter presents a review of the protection systems, except the painting systems, used for conservation purposes and highlights recent researches on a new corrosion inhibitor family.