Evidence of tin coating on archaeological ferrous artefacts by voltammetry of microparticules (VMP)

Voltammetry of microparticules (VMP) using a paraffinimpregnated graphite electrode (PIGE) to transfer material directly from the artefacts to an electrochemical cell, was applied on two objects from Medieval Ages covered by a grey metallic coating in a variable state of conservation and appearance as a non invasive analytical method to characterise artefacts. Results have shown that the light grey metallic surface layers observed on both objects present different chemical composition, which could be determined in a selective way, following their stratigraphical location of the artefacts