Assessment of material-atmosphere interactions during scanning laser cleaning of archaeological bronze alloys: A Roman coin case study

The main goal of this research was to assess the presence of possible reoxidation phenomena during laser cleaning procedures carried out on Cu-based archaeological artefacts. Previous studies conducted on archaeological and artificial corrosion layers, highlighted that the laser ablation procedures (removal of unwanted materials) do not change the composition of the corrosion layers and that detectable re-oxidation phenomena occur on laser-treated surfaces for intense laser conditions, not applicable on Cultural Heritage artefacts. A novel approach, recently developed on Material Science field by these Authors, is here applied in the Conservation Science field: the use of a traceable isotope combined with Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) on an archaeological bronze coin. This approach, applied for the first time on an archaeological artefact, allows assessing the presence of possible re-oxidation phenomena that might occur on object surfaces during optimised cleaning procedures.