Diagnostics and Analytical Campaign as Support for the Restoration Activity of a 14th-Century Mural Painting Representing the Virgo Lactans

The restoration of medieval wall paintings often involves the combination of heterogeneous techniques and materials considering their nature and period. One of the many obstacles in the study of the restoration of these types of artifacts is the paucity of sources that remain and the fragmentary nature of the paintings. As support, we can identify information about the modus operandi of the artists and artisans’ workshops that were active in the medieval period. Such information can be derived from important treatises-for example, Theophilus’ mid-12th-century treatise, the Diversarum artium Schedula, and chapter XV of Cennino Cennini’s Book of Art. These all coincide with the paintings presented in this paper, which represent the Virgo Lactans (or Madonna del Latte, Nursing Virgin) and a likely pre-existing figure of a praying woman. The investigated wall paintings are located in the porch of St. Andrew’s church, situated in the neighborhood of Pianoscarano (Viterbo, Central Italy). The historical context and the execution technique of the paintings were carefully studied, supported by a diagnostic and analytical campaign carried out by means of hypercolorimetric multispectral imaging, spot X-ray fluorescence spectroscopy using a portable instrument, Fourier transform infrared spectroscopy, and cross-section analysis. These analyses allowed us to characterize the original materials, the stratigraphic sequence of the paintings, and the previous interventions applied to the paintings’ layers, giving relevant data to support the recently concluded restoration.