Insights into the Blanching of Water-Damaged Varnish by Means of Spectral-Domain Optical Coherence Tomography

Abstract

ABSTRACT In consequence of the flooding of the Loing river in 2016, some of the storage areas for the Musée Girodet were submerged, with 3000 artworks affected. Following this, the painting Le Jeune Trioson (nineteenth century, attributed to the school of Anne-Louis Girodet De Roucy Trioson) developed severe blanching in the varnish, over the dark background in particular. An initial non-contact investigation with a spectral-domain optical coherence tomographic system operating in the near-infrared range (830–1020 nm) gave valuable insights into the development of this alteration. This detected a change in the scattering properties of the blanched varnish compared to the non-blanched one. The depth at which the modification occurred has been clearly identified, together with different stages of alteration corresponding to the severity of the visible blanching. This information obtained non-invasively is useful for guiding a later targeted sampling campaign and for informing treatment planning for varnish removal.