Art Restoration: The Culture, the Business and the Scandal
Like anything else, works of art inevitably change over time. Some of the pigments in Renaissance paintings are unstable, and the varnishes often used to protect the surface gradually become discoloured. Alterations in temperature and humidity, which happen anyway but are more acute when pictures are moved, cause panels to crack, canvases to sag, and paint to flake. Frescoes suffer from other problems. The Italian technique of buon fresco, involving the use of water-based mineral pigments on wet plaster, is remarkably durable, since the paint itself forms a chemical bond with the lime of the plaster, but the lime can react with various types of atmospheric pollution, often with unfortunate consequences. Further problems can be caused by damp, and still others by the intrinsically more fragile techniques of painting a secco, on top of dry plaster. Marble sculpture, which is chemically similar to the plaster used for frescoes, can also suffer from pollution and, as is inevitable, gradually acquires a darker surface, while bronzes too develop a natural patina (although, as with marble, this can be added artificially too).
Even if the physical changes were reversible, which most of them are not, it still would not follow that we could remove centuries of accumulated dirt to reveal the pristine work of art beneath. Many major works have been cleaned before, sometimes in destructive ways, or repainted, or both; and the process of cleaning can itself involve chemicals which may react with the materials below, sometimes with consequences that only gradually become apparent. Despite these dangers, restoration is seldom undertaken solely to counter physical threats to works of art, such as cracking or flaking; rather it aims to improve their appearance. Just what constitutes an improvement is of course conditioned by current taste. Few restorers would now contemplate covering Renaissance pictures with yellow varnish, but Dürer wrote in 1509 that all varnishes except the kind he made himself were yellow. We do not know whether this was true, but it seems likely that yellow varnish was common at that period and, presumably, that painters took account of it in their pictures.
The modern practice of covering old paintings with clear varnish therefore does not necessarily give a fair idea of how they originally looked, any more than does the habit of displaying them under strong artificial light. But the brilliant colors that we so often see today certainly meet the expectations of a public accustomed to slides and color reproductions. These are almost always brighter than the originals, even when the effect of colorplates is not artificially enhanced by thick black borders, as in the magazine FMR.
Most restoration used to be done by practicing painters, but now it has turned into a highly specialized activity, with a large and growing body of scientific literature. The process of professionalization and the introduction of new techniques for the physical examination of the works themselves often give an impression of objectivity and rigor to an activity that still calls for subjective judgments, not …