Elucidating Stradivarius' recipe

Fig 1. Five Stradivarius instruments from the Musée de la musique in Paris. From left to right, the "Davidoff" (1708), the "Tua" (1708), a "Long-Pattern" model (ca. 1692), the "Provigny" (1716) and the "Sarasate" (1724) (collection Musée de la musique, Paris, inv. num. E.1111, E.1375, E.1729, E.1730.1, E.1932 respectively). Credits : cliché A. Giordan © Cité de la Musique	The varnish used by Antonio Stradivarius, the legendary Italian violin-maker, to coat his prestige instruments has been the object of numerous controversial assumptions for more than two centuries. A "secret" recipe would thus be responsible for the famous and praised tone of his instruments. A study driven by the Cité de la musique in Paris together with an international team, which has just been published in the renowned journal Angewandte Chemie International Edition, shed unprecedented light on this subject. Researchers have determined the composition of the varnish layers on five Stradivarius instruments from the collections of the Musée de la musique, Paris. For the first time, this study shows that Stradivarius employed ingredients commonly used among craftsmen in the 18th century. Thanks in particular to the results obtained on the infrared microscopy beamline at SOLEIL synchrotron, it is shown that, on all the studied instruments, Stradivari applied two very thin varnish layers: The first one, simply oil-based, (similar oil as the ones used by painters) barely penetrates the wood. The second layer is a mixture of oil and pine resin. Stradivarius mixed in it various pigments used in easel paintings. This study shows the intention of Stradivari to sought a variety of tints for his instruments. Stradivarius' technique seems to be inspired from the painters'. It may explain the chatoyancy, the reflections of light, the texture of the violins varnished woods, which made him famous.  To reach these conclusions, a dozen of French and German research scientists have focused on five Stradivarius instruments from the collection of the Musée de la musique in Paris. The varnishes of the five instruments have been thoroughly studied with a wide array of complementary analytical techniques. Minute varnished fragments have been sampled and then analyzed at the synchrotron SOLEIL (plateau de Saclay), the most recent synchrotron facility in the world, at the Institute for Analytical Sciences in Dortmund (Germany) and in three laboratories of the French research agency CNRS (CRCC, LC2RMF, LADIR). This unique multidisciplinary collaboration, and the use of high-end analytical methods, on undisputed representative examples of the best of Stradivarius' work has allowed to decipher the ingredients and techniques of the Master violin-maker. Articles online : Le Monde.fr : Un des secrets des stradivarius dévoilé The New York Times : What Exalts Stradivarius? Not Varnish, Study Says Références : J.-P. Echard, L. Bertrand, A. von Bohlen, A.-S. Le Hô, C. Paris, L. Bellot-Gurlet, B. Soulier, A. Lattuati-Derieux, S. Thao, L. Robinet, B. Lavédrine, S. Vaiedelich. Nature of the extraordinary finish of Stradivari’s instruments, paru le 4 décembre 2009 dans Angewandte Chemie International Edition http://dx.doi.org/10.1002/anie.200905131 (édition internationale en anglais) et Zusammensetzung und Aufbau des berühmten Stradivari-Lackes, paru le 4 décembre 2009 dans Angewandte Chemie http://dx.doi.org/10.1002/ange.200905131 (édition allemande). Authors : J.-P. Echard, B. Soulier, S. Vaiedelich Laboratoire de recherche et de restauration Musée de la musique, Cité de la musique, Paris, France L. Bertrand, L. Robinet IPANEMA - Synchrotron SOLEIL Gif-sur-Yvette, France A. von Bohlen Institute for Analytical Sciences (ISAS) Dortmund, Allemagne J.-P. Echard, A. Lattuati-Derieux, S. Thao, B. Lavédrine Centre de Recherche sur la Conservation des Collections MNHN-CNRS-MCC Paris, France A.-S. Le Hô Laboratoire du Centre de Recherche et de Restauration des Musées de France (C2RMF) UMR171 CNRS - MCC, Paris, France C. Paris, L. Bellot-Gurlet Laboratoire de Dynamique, Interactions et Réactivité (LADIR) UMR 7075 CNRS and UPMC - Université Pierre et Marie Curie Paris 6 Thiais, France B. Soulier Staatliche Akademie der Bildenden Künste Institut für Technologie der Malerei Stuttgart, Allemagne The authors thank P. Dumas and C. Sandt (SMIS, SOLEIL synchrotron), D. Jaillard, (CCME Univ. Paris-Sud), M.-A. Languille (IPANEMA, SOLEIL) and E. van Elslande (C2RMF). The authors acknowledge the essential collaboration of T. Maniguet, curator (Musée de la musique), for authorizing the sampling of the musical instruments. B.H. Berrie, M. Spring, P. Laszlo and T. Blundell carefully reread the manuscript. Part of this work was supported by the European Commission FP6 IA-SFS transnational programme.
Fig 2. Infrared microscopy image obtained on the SMIS beamline, SOLEIL synchrotron, on the varnish cross section of the "Provigny" violin (A. Stradivari, 1716, Cremona, coll. Musée de la musique E.1730.1). The image allows identifying and localizing the organic compounds of the varnish (oil – resin) at the wood cells scale, and to exclude the presence of proteinaceous materials. Credits : cliché L. Bertrand © Synchrotron SOLEIL
Fig 3. Cross section of the varnish of the "Provigny" (A. Stradivari, 1716, Crémone, collection Musée de la musique, Paris E.1730.1). From bottom to top : wood cell structure, the first oil-based layer impregnating the wood (whitish), the top layer, a mixture of oil and resins, with pigments admixed (yellow-orange). Credits : cliché J.-P. Echard © Cité de la Musique