On the application of optical coherence tomography as a complimentary tool in an analysis of the 13th century Byzantine Bessarion reliquary

Accepted version (after embargo period) This work presents the results of an application of optical coherence tomography (OCT) to examine a 13th century Byzantine reliquary of unparalleled artistic and historical value. The aim of this work, performed at the initial stage, before the restoration, was focused on the resolution of cleaning procedures regarding both the thick, old varnish and the gold leaf details finely applied on the painted parts of the artwork by means of an integrated approach of non-invasive and invasive analyses and diagnostics. The results allow definition of the thickness of the varnishes, their inner morphology and establishes the presence (or absence) of secondary layers of gold leaf upon the original ones. Knowledge of varnish thickness and in-depth localisation of the secondary gold leaf allowed the restoration procedure of cleaning and thinning of the altered varnish to be performed safely and effectively in order to recover the wonderful pristine sight of a precious and ancient byzantine work of art.