X-ray tomography of large wooden artworks: the case study of “Doppio corpo” by Pietro Piffetti

X-ray computed tomography (CT) is now widely used in the Cultural Heritage field thanks to its non-invasivity and for the high number of information which can be obtained on the inner structure of the object. Until recently only medical devices have been used, permitting the analysis of only some particular artworks with small size (to fit the acceptance of medical CT scanners) and materials (similar to human tissue). To overcome these limitations a custom instrumentation has been designed and built to perform analysis on artworks, of very different sizes, shapes and materials. In the frame of the neu_ART project, aiming to develop state of the art transmission imaging and computed tomography, a facility for the X-ray tomography of large size artefacts has recently been installed in a dedicated area of the Centro Conservazione e Restauro “La Venaria Reale”. This instrument is based on a X-ray source (up to 200 kV), a linear X-ray detector (50 cm long) and a high precision mechanics (both for the movement of the source and the detector, and for the revolution of the object). With this device one can obtain information both on materials, constructive technique and state of conservation of an artwork before the restoration process. In this contribution the results obtained with this instrument on the first large object are presented. It is the “Doppio corpo”, a piece of furniture masterfully inlaid by Pietro Piffetti, the most famous cabinet-maker in Piedmont in the XVIII century and now housed in the Quirinale, the official house of the Italian President in Rome. This analysis permitted to obtain fundamental information about the state of conservation, previous restorations and the distribution of various materials (different kind of woods and metals, ivory, etc.). Moreover the dimensions and arrangement of several wooden pieces used by the author have been evaluated, allowing interesting hypotheses about the constructive technique of this masterpiece.