The Ketone-Based Varnish Removal from an Oil Painting by Wassily Kandinsky: Comparison and Assessment of Cleaning Methods Through Preliminary Test on Mock-Ups and Multi-Analytical Investigation

This paper presents the removal of a non-original varnish from the surface of a painting by Wassily Kandinsky based on prior experimentation carried out on mock-ups, which were made according to the original artistic technique and painting stratigraphy. Due to a generally serious state of conservation, the artwork underwent several treatments over the years that have changed its original appearance. This work focused on the study and characterization of the ketone-based varnish present on the surface to outline how this non-original film layer interacted with paint layers and increased deterioration phenomena. Aiming to identify the most suitable approach for the artwork, some preliminary cleaning tests were made on artificially aged mock-ups. A multi-analytical investigation was carried out through non-invasive and invasive techniques to support all steps of the conservation treatment. By comparing cleaning results on mock-ups, a suitable protocol was developed and applied to the original painting. The best results were obtained by using the Nanorestore Gel® Dry MWR (Medium Water Retention) with ethanol. The project has shown that the dissolving power of the solvent can effectively be controlled and limited at the surface by confining it to the nanostructure of the gel, thus minimizing the risk of interaction with the original paint layers.