Exploring the potential of a frequency resolved acoustic imaging technique in panel painting diagnostics

A new application of a contactless and low-cost acoustic imaging technique, for the diagnostics of the structural damage in panel paintings is presented. The artworks, exposed to a wide frequency band acoustic excitation, are analysed in terms of acoustic energy absorption coefficient in the audio frequency interval. The method reveals buried defects, such as detachments of the painted layer and flaws in the wood substrate, providing frequency resolved acoustic images. Three case studies are here discussed; the wood substrate configuration and the conservation state of the painted layer greatly differentiate the examined paintings. A collection of acoustic images is presented, highlighting a plurality of features characterized by different geometry and frequency response. The study gives a representative visualization of the response of panel paintings to the acoustic excitation, suggesting a reliable usefulness of this technique in their safeguard. This knowledge base will orient the future validation on properly designed laboratory models.