Sub-ablative LQS Nd:YAG laser irradiation effects on cadmium yellow paint layers

On the wake of recent successful applications of LQS Nd:YAG (1064 nm) laser in conservation of modern easel paintings, here, we focus on the study of undesired side effects of the laser treatment that can occur in photosensitive modern paints. Understanding the phenomenology and nature of their alterations has a crucial importance for extending the laser approach in conservation. In the present work, a measurement methodology for characterising the sub-ablative effects of photosensitive paint layers was developed. The analytical approach was refined by considering the example case of cadmium yellow. CdS-based paint mock-ups using different oily binders were prepared and systematically laser irradiated under an epifluorescence microscope coupled to a spectrometer. The latter, image analysis, and ESEM-EDX allowed to collect information on the alteration phenomenology. The method provided underlines the strict dependence of the damage nucleation on the distribution of the pigment within the matrix along with a set of other features of interest for defining and assessing the laser treatments