The study of surface optical properties for characterizing the cleaning process of artworks
“Cleaning” is a process that involves a carefully identification of the causes of any deterioration or discolouration and then the removal or treatment of the layers altered or dirty. The skill of the restorer is not only to understand the techniques and media used by the artist, but also to recognize what beauty lies beneath the veils of many years of neglect or adverse conditions. Surface cleaning is then one of the most important and sometimes controversial stages of the conservation process: it is an irreversible process that generally results in substantial physical changes of the object surface, raising thus a series of questions regarding aesthetics, the potential loss of historical information and the ability to control the cleaning process adequately. Decisions have to be made regarding partial or complete removal of varnish: technical considerations include selection of a method that allows a great deal of control in the cleaning process, so that undesired layers can be removed without damaging the underlying ones by means of traditional cleaning methods, including mechanical or chemical removal.
Optical techniques at our disposal, used in order to get the most information on the cleaning process are:
1) Multispectral Scannig Imaging in the visible and infrared regions (VIS-NIR 32 bands from 400 nm to 2500 nm).
2) UV Fluorescence Imaging
3) Conoscopic Scanning Microprofilometry
4) OCT Scanning Microprofilometry
5) Confocal Scanning Microprofilometry