EIS measurements for the assessment of the conservation state of metallic works of art

The in-situ conservation of metallic artefacts of artistic and historic interest is a scientific challenge. The characterization of surface conditions of the artefacts is mandatory to estimate the effect of the atmospheric corrosion on the metal. Electrochemical impedance spectroscopy (EIS) is a technique that can be employed in order to investigate the phenomena involved at the electrochemical interfaces and to predict the corrosion process. In this paper, a portable instrument specifically realized for EIS measurements on metallic works of art is presented, and the measurement results on two case studies are discussed: the iron bar chains in the Notre Dame Cathedral in Amiens (France) and a large weathering steel monument exposed outdoor in Ferrara.