A multidisciplinary non-destructive study of historical pipe organ fragments

The degradation of ancient tin-based pipe organs has still many open questions. Different kinds of alteration may affect tin-rich alloys: (i) the interaction with the environment, leading to localised tin corrosion and (ii) the so-called tin-plague, that is a consequence of a change of tin crystal structure (from beta-tin to alpha-tin phase). In both cases, the morphology of the deteriorated area can be very similar, with grey pustules, pinholes, cracks and exfoliations. A multidisciplinary non-destructive study has been carried out on ancient pipe organ fragments, trying to infer whether the spatial occurrence of different crystallographic phases (that is alpha-tin, beta-tin, cassiterite or romarchite) reflects the visible alterations patterns. We aim to demonstrate that neutron and Raman techniques can give relevant indications in archaeometallurgy studies of cultural heritage artifacts, where only non-destructive experiments can be performed. We could indeed derive the presence of the beta-tin phase. Several tin oxide phases have been detected too, associated with the visible occurrence of “grey regions” and hole borders (mapped by Raman spectroscopy), and hydrate phases (mapped by neutron imaging). The combination of the two probes could be considered a protocol to be applied in the characterization of tin based specimens [1]