Gli stucchi di Giacomo Serpotta nella Cappella della Vergine di Guadalupe (chiesa di Santa Maria degli Angeli, Palermo): rilievo ed analisi mineralogiche-petrografiche

Object of this study are the decorations in plaster realized from Giacomo Serpolla in the 1706 in Chapel of the Vergine di Guadalupe, situated in the Church of Santa Maria degli Angeli (note also like Gancia) in Palermo. The relief was carried out using grates on looms in wood that, combined to photographic assemblages performed on scaffoldings and easels, have allowed a reconstruction as more possible faithful of the real volumes. The punctual relief of all the elements has been made functional to the following virtual restitution, realized with software of vectorial graphics, with the aim of appraising the iconographic architectural aspects and of furnishing a precise indication of the points of sampling as well as of the zones interest from the phenomena of deterioration. Mineralogical-petrographic analyses were realized by means of Xray diffractometry (XRD), polarising microscopy (thin cross sections) and electron scanning microscopy (SEM/EDS). They have .allowed to establish tbc stratigraphic succession in the plasters object of the study and define tbc compositions of the sandy aggregate and of the binder, in the internal mortar layer as well as in the external finishing layer. Through the same techniques, besides, has been possible to characterize the products of deterioration (efflorescences of soluble salts: mainly magnesium sulphates) which have also caused the breakup and the separation of substantial parts of the sculptures