HYPERSPECTRAL IMAGING FOR EARLY DETECTION OF ALTERATION PHENOMENA IN PAINT LAYERS

Hyperspectral imaging (HSI) is a technique that can be applied in various fields of science and recent developments in hardware and software allow to increase its power and to decrease the costs of the analysis based on reflectance spectrum in the visible and near infrared wavelength range. This monitoring technique is particularly suitable for pigment classification and for the monitoring of pictorial materials without the need of sampling [1]. In order to study the alteration of paint layers by solar aging , samples were prepared with different pigments, binders and supports and artificially aged using solar box. The results obtained for a sample composed by yellow ocher mixed with Arabic gum and applied to a canvas support are presented in this work [2].The sample was acquired in the VIS-NIR (400-1000 nm) and SWIR (1000-2500 nm) ranges by HSI after196 hours and 400 hours. Besides, for comparison, color measurements were carried out before and after aging the sample to monitor color changes during the two steps. The goal of this study is to verify the possibility to detect alteration phenomena before they become macroscopically visible by HSI in the VIS-NIR and SWIR ranges