The Early Use of Prussian Blue in Paintings

As far as is known, the pigment Prussian blue was synthesised for the first time in Berlin in the early 1700s. It is commonly assumed that the pigment was not used in paintings before the 1720s. The presence or absence of this pigment is often used to answer questions concerning the dating and authenticity of art objects from the 18th Century. For the very first time, a large collection of French 18th Century paintings by Antoine Watteau (1684-1721) and his circle has been studied in detail. The pigments of more than fifty paintings from the collection of Frederick II of Prussia have been analysed with non-destructive methods using a complementary combination of micro X-ray florescence analysis, optical microscopy and spectroscopy in reflection mode. Most interesting in this context is evidence of Prussian blue in two earlier works by Watteau from about 1710. It shows that Prussian blue must have found its way from Berlin to Paris by around 1710 at the latest. In the search for further proof that Prussian blue was used in paintings dating back to the same years, we also analysed blue pigments in works by painters of the Prussian court, and of other European courts. The court painters were closely connected to the Royal Academy of Arts in Berlin, where the pigment was available no later than 1709. This investigation shows that Prussian blue was used by painters at the Prussian court, in Rotterdam, and Paris much earlier than previously assumed. It was already used in 1710, and this to a surprisingly large extent. To date, the painting "Entombment of Christ", dated 1709 by Pieter van der Werff (Picture Gallery, Sanssouci, Potsdam) is the oldest known painting where Prussian blue has been used. Historical sources and the material findings mentioned above date the first synthesis of the pigment by Johann Jacob Diesbach in Berlin to about 1706. INTRODUCTION The Prussian Palaces and Gardens Foundation Berlin-Brandenburg in Potsdam, Germany, is presently preparing a catalogue of its collection of French 18th-century paintings collected by Frederick II of Prussia (1712-1786) [catalogue]. Works by Antoine Watteau (1684-1721), Nicolas Lancret (1690-1743), and Jean-Baptiste Pater (1695-1736) feature prominently in this collection. A team of art historians, restorers and scientists is currently investigating more than 50 paintings. For the first time, one of the largest collections of its kind is being studied in-depth. This study shows that the pigment Prussian blue, an iron hexacyanoferrate complex compound, was used by the painters in Paris much earlier than has been previously assumed [Bartoll et al.]. Most surprising was the evidence of Prussian blue in two earlier paintings by Watteau: "La mariée de village" (SPSG, Potsdam, Sanssouci Palace, see Figure 1) and "Embarkation to Cythera" (Städel Museum, Frankfurt). Both paintings are conventionally dated to around 1710. Prussian blue was synthesised for the first time in Berlin in the early 1700s. Most literature on pigment history assumes that Prussian blue was rarely or not used by painters before the 1720s. Harley wrote in this context: "...one might expect the pigment to have been acclaimed 1 9th International Conference on NDT of Art, Jerusalem Israel, 25-30 May 2008 For more papers of this publication click: www.ndt.net/search/docs.php3?MainSource=65