Optical Coherence Tomography Based Measurements to Support Cleaning Treatments of Painted Ancient Artifacts

Optical Coherence Tomography (OCT) is an imaging technique commonly used in the biomedical field to obtain below the surface pictures of the tissues. Being a non-contact, fast, and non-invasive method, it can also support conservators during cleaning treatments of painted ancient artifacts. The paper analyzes the reliability of the estimation of the protective varnish thickness from OCT images. Several samples made of Paraloid® B72, a protective material commonly used in conservation, applied on Egyptian blue painting were realized and characterized in comparison with scanning electron microscope images, which is the ultimate tool of conservators to assess the composition and morphology of the surface of artifacts. The results proved to be very promising as the two techniques led to compatible results, demonstrating that OCT can become a routine tool for online monitoring of cleaning treatments.