Portable EDXRF surface mapping of sulfate concentration on Michelangelo’s David

The study presented in this paper was carried out within a large international project founded in the context of the Michelangelo’s David’s 500th anniversary celebration. A group of experts analysed Michelangelo’s masterpiece with several techniques with the aim of helping restorers to choose the most suitable treatment for cleaning of the statue. The task of the present team was to map the possible presence of sulfur (as sulfates) on the surface of the sculpture due to pollution effects. A portable energy-dispersive x-ray fluorescence (EDXRF) system was used. The EDXRF technique is not only non-destructive, sensitive and capable of simultaneous multi-elemental analysis but also, in its portable version, it allows the analysis of many areas before, during and after restoration. A large number of measurements were made to obtain an overall picture of the sulfur distribution on the sculpture and then further measurements were made at selected strategic points. After applying different removal procedures at each of these points, the measurements were repeated to obtain a quantitative evaluation of the effectiveness of each cleaning procedures. The results are presented and discussed