Historically Accurate Reconstructions of Artists ’ Oil Painting Materials

Introduction Painting reconstructions usually suggest the reproductions of old master paintings which many conservation training programmes and art techniques courses include so that their students may learn about traditional painting techniques. Reconstructions, however, are also made to answer specific questions in conservation research, either in relation to analysis or to model proposed treatments. Such reconstructions are not necessarily fully accurate in terms of the materials, nor are they required to be, as toxicity issues alone impose practical limitations. This paper explores projects where historical accuracy, as far as is possible, is the objective. Naturally there are compromises, since modern materials are unlikely to have precisely the same chemical and morphological identity as those used in the past. However, the attempt to recreate historical recipes with a high degree of accuracy provides sometimes surprising outcomes and unanticipated results The Purpose Art technological research (or technical art history) is gradually becoming recognised as a field in itself. Understanding how a particular work of art was created, and with what materials, can greatly enhance our interpretation of the work, its authenticity or place within the artists’ oeuvre, and its contextual relationship to contemporary works (that is, how innovative the artist was with his technique or materials). This research is highly dependent on historical documentary sources (recipes, images and observations), and on information gained through the examination of original paint samples with optical microscopy and materials analysis. There is, however, a gap between what can be learned from historical recipes on the one hand and from analytical results on the other. Analysis produces more and more sophisticated and reliable lists of materials present while recipes, although often fragmentary, inform us of their use. But, at a certain point, to enter the experience of the artist and his assistants, and to understand their materials, the recipes themselves must be followed. Only in this way can we investigate their validity and compare their products with what is found in original artworks. By making reconstructions with historically appropriate materials, we can learn why materials were prepared in a certain way, what governed the artist’s choice, and how such materials behave in application, thereby gaining direct insight into workshop practices. For example, traditional mastic varnish recipes recommended ageing prior to use, for a minimum of nine months. When an aged varnish, prepared according to a traditional recipe, was compared with one freshly made (following the same recipe), the older varnish was silkier, brushed out better and allowed a longer working time before setting – features that could not be anticipated through chemical analyses alone (Carlyle 2005). Similarly, following a contemporary recipe for an artists’ medium demonstrated that brushwork and surface features observed on actual paintings were characteristic of the medium used (Townsend et al 2005). Once recreated, the products of old recipes can function as reference samples for comparison with what we see and find through analyses, and to assist the interpretation of analytical results (van den Berg et al. 1999; van der Doelen 1999; van den Berg 2002). To evaluate change and when it occurred in the course of a painting’s history, we need to know how painters’ materials behave over time. Certain paint defects may be very visible now, but why and when they developed is not clear. How did a painting appear and behave when the paint was fresh? Reconstructions with historically accurate materials can be designed to answer these questions (van den Berg et al. 2005). TATE’S ONLINE RESEARCH JOURNAL