Noninvasive Analytical and Diagnostic Technologies for Studying Early Renaissance Wall Paintings

Electromagnetic imaging technologies, working at different frequencies, are widely exploited for noninvasive diagnostics since they allow an improvement of knowledge about the surveyed object without affecting its state of conservation. In this paper, imaging technologies, working from microwaves up to ultraviolet frequencies, are considered and their basis is reviewed by focusing the attention on their application in the frame of cultural heritage. Specifically, ultraviolet fluorescence, infrared reflectography, TeraHertz imaging and ground penetrating radar are taken into account and a survey protocol, based on their complementary and cooperative use, is proposed as a best practice for analysis and management of artistic masterpieces. The cooperative use of different technologies makes it, indeed, possible to investigate the same work of art by accounting for different aspects characterizing its drawing, creation and possible restoration, thus providing a global vision from the support up to its outermost layer. The advantages provided by the cooperative use of the above-listed technologies are, herein, discussed with respect to the case study of the wall painting annunciation by Fra Angelico, one of the masterpieces of the early Italian Renaissance located at the Museum of San Marco in Florence, Italy.