Surface investigation of some medieval silver coins cleaned in high-frequency cold plasma

Processing in cold plasma (cleaning and/or decontamination) represents an ecological alternative for applications in various domains of a diverse range of materials. Considering the advantages it presents, high-frequency cold plasma has been employed to remove the corrosion products found on the surface of some silver coins pertaining to a Polish medieval numismatic collection. The effects of plasma treatment have been evaluated through the investigation of the coin surface before and after the treatment, by means of different analytical techniques: scanning electron microscopy–energy dispersive X-ray microanalysis (SEM–EDX), X-ray diffraction (XRD), FTIR spectroscopy and colorimetric measurements.