From noise to information. Analysing macro-XRF mapping of strontium impurities in Raphael's Baglioni Entombment in the Galleria Borghese, Rome

In the paintings of the Old Masters, strontium is present only as an impurity of the materials, that is the gypsum used for the preparation of the panels, and for this reason its presence is generally considered – at best – accidental information. However, an in-depth study of the distribution of strontium beneath the surface of Raphael's Entombment in the Borghese Gallery in Rome by means of MA-XRF provided detailed information regarding a reapplication of the preparatory gypsum ground layers on an area probably damaged before the painter began the execution of the painting. Furthermore, the comparison of MA-XRF distribution maps for lead and strontium with radiographic images, aimed to establish at what point the painter decided to eliminate a female figure in the centre of the painting, and the state of completion of the figure when this occurred.