Study of Wall Paintings and Mosaics by means of Ultraviolet Fluorescence and False Colour Infrared Photography

This paper reports the results of the application of ultraviolet (UV) fluorescence and false colour infrared (IRC) photography to the study of wall paintings and mosaics. The case studies proposed in this work are the wall paintings in the crypt of the medieval church of Sant’Andrea in Viterbo (Italy) and the fragment of wall mosaic with an Angel, coming from the Giotto Navicella, at present placed in the Grotte Vaticane. This mosaic fragment was examined on the occasion of the restoration carried out from November 2004 to February 2006. This restoration intervention was promoted and funded by Bonifacio VIII Committee on the occasion of the celebrations for the VII centenary of the death of Bonifacio VIII. Ultraviolet (UV) fluorescence and false colour infrared (IRC) photography are non invasive methods of analysis useful for a preliminary and sometimes resolutive investigations of works of art. The main advantage of these techniques is their simplicity and inexpensiveness but, at the same time, they made possible an overall examination of the work of art before starting with more sophisticated and in-depth investigations. There are few references about the application of this kind of analyses to the study of wall paintings and mosaics, so the aim of this research was to apply these photographic methods to some wall decorations and at the same time to several specimens carried out in laboratory to have a valid comparison. The aim was also to prove the potentiality and usefulness of these methods especially in the examination of mosaics because taking samples for laboratory analyses is often impossible