Investigation of laser cleaning procedures for the restoration of burnt paintings

The present work aims to further investigate the effects of laser cleaning of the burnt Parthenis' paintings, and to the development of a restoration procedure with the use of pulsed lasers, in combination with several characterisation methods. The evaluation of different types of laser, such as Nd:YAG laser with five harmonics, Er:YAG laser, and CO 2 using various fluences on different areas of the painting has been already performed and published1. In this work, and taking into account the previous results as well as the respective literature 2, 3 , untreated parts of the burnt paintings were cleaned with the optimum combination of laser parameters. The cleaning process was thoroughly examined with X-ray diffraction (XRD). In addition, the stratified layers of the paint were determined giving valuable information about the inner layers of the paintings. In the previous published work 1 , the optimum cleaning parameters have been assessed with the assumption that one single laser will be used to clean the entire surface of both burnt paintings. Nevertheless, thickness differences of the layers of the applied paint lead to the necessity of investigating the use of multiple lasers and of different parameters according to the required degree of cleaning. Therefore, restoration procedures based on multiple lasers or on a single laser, with varying parameters, are evaluated. One more technique to be introduced here is the visual digital reconstruction of the burnt paintings, which has the potential to provide an estimate of the degree of the required treatment.