Comparison of the Use of Traditional Solvents and Nanosecond 213 nm Nd:YAG Laser in Thinning Naturally Aged Varnish on a Contemporary Oil Easel Painting

Abstract

The removal of aged varnish on artistic paintings is a delicate intervention and the use of UV laser for this purpose is of special relevance. In particular, the use of nanosecond-pulsed lasers operating at 213 nm has been noted to produce good results in mock-up samples, but it has not been tested in real artworks. In this paper, we report on the application of this procedure for the first time on a contemporary oil easel painting with naturally aged varnish. The obtained results were compared with those achieved using traditional solvents, specifically a mixture of ligroin:acetone. Additionally, hot water was used to remove surface dirt. The performance of the different cleaning procedures was assessed with a range of techniques, including low-power microscopy, UV lamp illumination, laser-induced fluorescence (LIF), and laser-induced breakdown spectroscopy (LIBS). Of the tested treatments, the best performance is obtained by nanosecond laser irradiation at 213 nm using an adequate laser fluence (typically 0.14 J/cm2) that allows controlled and efficient removal of the outermost aged varnish layer without affecting the underlying non-aged varnish and paint layers.

Analytical Evaluation of Laser Cleaning Effectiveness in the Context of Contemporary Muralism

“…Among these advancements, the widespread adoption of laser cleaning technology has emerged as a transformative force, successfully applied to a remarkable array of historical treasures. Over the past two decades, laser cleaning has been widely employed to preserve diverse materials including stones, paintings, and archaeological finds such as metals, textiles, wood, glass, bones, and more [1][2][3][4][5][6][7]. Unlike conventional cleaning methods that often involve the use of solvents, which might be harmful to the environment and operators, laser ablation technology offers a sustainable alternative that overcomes the limitations of chemical processes.…”