Laser-cleaning effects induced on different types of bronze archaeological corrosion products: chemical-physical surface characterisation

Archaeological bronzes (Cu-Sn alloys) might be different in composition and these variabilities lead to a different interaction with the environment and, if they were buried, with several chemical elements present in soils. Generally, the result is the presence of complex corrosion products layers on the Cu-based artefacts which might be protective or reactive (and so dangerous) for the artefacts preservation itself. Moreover, the corrosion products can also be unwanted because hide the drawings present/imprinted on the original metal surfaces. So, for several reasons, it can be necessary to remove the unwanted corrosion products: laser-cleaning procedure is one of the most selective cleaning technique used. The main goal of this work was to assess possible laser-cleaning induced surface effects on different archaeological bronzes corrosion products structures through a systematic and multi-technique compositional study. Chemical-physical characterisations were performed on laser-cleaned and non-cleaned types of Cu-Sn archaeological corrosion products structures. The results show the efficiency and the low-invasiveness of the treatment.