Microbiological deterioration of metallic cultural artifacts

Although metal is comparatively resistant to deterioration, metallic cultural artifacts generally become eroded depending on the storage conditions. Metallurgical investigations on a number of ancient bronze mirrors have been performed by authors and the formation of pure copper lumps and unidentified corrosion products was confirmed on the surface of the mirrors and in the corroded layers. Accordingly, investigations to identify the corrosion products were performed by using an electron probe micro analyzer (EPMA), a scanning electron microscope (SEM) equipped with an energy dispersive spectroscope (EDS), a micro-X-ray diffraction analyzer (μ-XRD), and an X-ray photoelectron spectroscope (XPS). The evidences from the analyses suggest that microorganisms could have been the cause of the corrosion products. Researches and investigations are under way to confirm this perspective. This paper reports on the results obtained by now and visions of the future. In case that the process of microbiological deterioration of metallic cultural artifacts is clearly ascertained, we expect it will contribute to the advancement of conservation science for cultural artifacts.