Optical NDT supporting the restoration of a marble sculpture on the facade of the Gesù Nuovo church in Naples

Abstract

The study focuses on an angel marble sculpture, placed on the central portal of the Gesu Nuovo church in Naples. The non-destructive and noninvasive optical techniques used were Active Thermography (AT) and 3D scanning. The measurements were carried out before and after the restoration of the marble sculpture, consisting in the consolidation of some disintegrated areas and in the removal of both black crusts and biodeteriogens, present in various areas of the sculpture. AT images provide a map of the structural homogeneity of the investigated areas, measuring the thermal response, which result altered where the degradation products are located (crusts and/or biological patinas). 3D scanning, on the other hand, allows obtaining a 3D model of the entire sculpture and measuring any structural variations due to the restoration on a millimeter scale.