Combination of a solvent-dispensing and micro-aspiration device for removal of varnishes on painted surfaces

The use of organic solvents in treatments for the removal of varnishes on easel paintings is still a common practice among conservators worldwide. The more polar solvents required for aged, oxidized varnishes may promote leaching of fatty acid components of oil-based paints. The strategy tested in this study to reduce the diffusion of the solvents, in an attempt to minimize interactions, relied on the use of a system composed of two devices: a pump for delivering a precisely controlled amount of solvent to the surface, and a solvent-proof membrane pump to quickly aspirate it. This method was compared with two traditional methods of solvent application, to remove the varnish on two oil paintings on canvas, one from the twentieth century and the other dated 1872: swab-rolling and application through a Japanese paper sheet. The extent of leaching was measured by GC−MS analysis of the paint samples taken from the treated areas. The profiles of the fatty acids before and after varnish removal could thus be compared.