AIC's 47th Annual Meeting

When varnish ageing affects the readability of a painting or the protecting powers of such varnish, interventions as cleaning or varnish removal are implemented. Although these procedures are commonly performed in conservation studios, they are quite dangerous, considering their irreversible nature. Traditionally, such procedures were carried out using organic solvent mixtures. However, beginning in the 1990s, the ongoing collaboration with scientists has led to new approaches developed for the cleaning of paintings and the removal of film-forming materials. Those new methods are not so widespread in conservation studios in Argentina. Therefore, their effectiveness and scope are not known, which is why conservators continue using solvents almost exclusively, unaware of the potential benefits of new techniques. The aim of this research is to compare the effectiveness of non-traditional methods for varnish removal with the use of traditionally-established solvents and to encourage the use of such new methods as well as interdisciplinary work in the country. Based on the current literature on the subject, different aqueous methods and emulsions were prepared to use as samples of non-traditional methods. As for traditional ones, increasing polarity tests were selected using hydrocarbon solutions of proven effectiveness. An experimental plan was designed to age mock ups of varnishes composed of different types of resins using an accelerated ageing chamber. The aim was to recreate the physical-chemical features of aged varnishes found in artworks. An empirical test was performed on each varnish using different methods. Through several techniques applied to artwork analysis, emulsions were found to be the most effective among non-traditional methods, notably polymeric, Pemulen TR-2-based emulsions, which proved highly successful, despite their low solvent percentage. Such effectiveness lies in the combination of water and solvents, allowing for the removal of resins which have become partially hydrophilic with ageing, using a lower solvent percentage and less polar solvents than those used with solvent-only removal. These new methods can not only provide a solution to the problem of toxicity risk associated with the use of organic solvents but also prove to be more selective in some cases, thus minimizing the risk to which the work is exposed. Varnish removal using non-traditional methods requires a deeper knowledge of the physical-chemical theory of processes involved, allowing for the development of specific mixtures tailored for each case, which is why ongoing interdisciplinary work with chemists contributing to the process is essential. This paper aims at bringing to the surface new varnish removal methods that can lead to the introduction of improved, more rational approaches in conservation studios in Argentina.