Mural Painting Discovered in the Crypt of the Cathedral of Parma (Italy): Multi-Technique Investigations for the Conservative Restoration Project

In October 2021, a mural painting was discovered in the crypt of Parma Cathedral (Italy). It was covered by a wall, erasing it form historical memory. The painting, presumably from the 15th–16th century, depicts the Madonna and Child enthroned in the center, between Saints Peter and John. Before the restoration project, investigations were conducted with different techniques to identify the pigments and binders used, the nature of the surface finish and the efflorescence. Micro-Raman spectroscopy detected numerous pigments compatible with the presumed age. An interesting result concerns the presence of crocoite (lead chromate), an unusual and rare pigment for this period. These pigments were confirmed through investigation by means of Scanning Electron Microscopy coupled to Energy-Dispersive X-ray Spectroscopy (SEM-EDS). Fourier Transform Infrared Spectroscopy (FT–IR) and Gas Chromatography/Mass Spectroscopy (GC/MS) were used to identify the binder and the type of wax used in the finish layer. The rather widespread presence of egg, used to spread the paint, allows us to affirm that this mural painting was created as a fresco, with substantial parts a secco.