Non-destructive exploration of late Gothic panel painting using X-ray tomography and flattening of the reconstructed data

Abstract

The use of computed tomography (CT) for studying artwork has a long tradition in the restoration and care of collections in memory institutions. The result of the related tomographic reconstruction is a virtual spatial model in which we can examine the production technology, the internal structure, various damaged areas, and previous restoration interventions. The extension of standard CT to dual energy CT provides additional information to help distinguish materials with similar densities but different chemical compositions. As will be shown, pigment differences that appear very similar in optical light can be identified in this way. The differences found were confirmed by X-ray fluorescence and Raman spectroscopy analytical techniques. Current laboratory CT scanners make it possible to examine the layered structures of paintings and polychrome sculptures. In the case of wood panel paintings, however, we are faced with the common deformation of the panels. So, when examining the CT data, we can only see a small section of the paint layer, and it is difficult to examine the whole artwork in its entire context. This disadvantage can be solved by a virtual straightening of the panel, as will be demonstrated.