ANALYSIS OF INORGANIC MATERIALS FROM PAINTINGS AND WATERCOLOURS BY PAUL CÉZANNE FROM THE COURTAULD GALLERY USING TWO METHODS OF NON-INVASIVE PORTABLE XRF WITH LIGHT MICROSCOPY AND SEM/EDX SPECTROSCOPY Aviva Burnstock 1 , Elizabeth Reissner 1 , Clare Richardson 1 , Klaas Jan van den Berg 2 1 Courtauld Institute of Art, Department of Conservation & Technology Somerset House, London WC2R ORN, UK 2 Instituut Collectie Nederland (ICN), Amsterdam, The Netherlands ABSTRACT The inorganic materials used by Paul Cézanne for six paintings and five watercolours from the Courtauld Gallery, London have been examined using two kinds of portable X-ray fluorescence (XRF) equipment and IR reflectance spectroscopy, and analysis of paint samples using Light microscopy (LM) and SEM-EDX. The aim of the study was to define parameters for identification of inorganic pigments, extenders and preparation layers in the works, and to assess the resolution and reliability, advantages and shortcomings of the portable techniques by comparison with sampling methods. Results of the analysis of a painting The Montagne Sainte-Victoire c1887, and a work on paper Apples, Bottles and Chair Back 1904-1906 are given. XRF using both types of equipment was useful for the characterisation of some of the inorganic materials used for works on canvas, and in particular the watercolour on paper, where it was not possible to take samples for SEM/EDX or other techniques. For the painting, XRF data required complimentary data from LM and SEM/EDX for characterisation of the inorganic materials in mixtures or layers, while XRF with LM was sufficient for characterisation of the inorganic materials in the watercolour where pigments were used unmixed and in a single layer. INTRODUCTION A technical and historical study of paintings and works on paper by Paul Cézanne (1839- 1906) in the Courtauld Gallery included characterisation of pigments used for the works using a combination of non-invasive analysis using two kinds of portable XRF equipment. XRF has been widely applied for the characterisation of inorganic materials in works of art, with more recent developments in the technology providing portable easy to use equipment that has facilitated the use of the technique by conservators (see for example Ferretti 2000). In the present study identification of pigments and inorganic materials was based on deduction from elemental analysis using XRF, using portable equipment used by the MOLAB group, and with a handheld Bruker portable XRF instrument. The MOLAB instrument allows the detection of elements with atomic number higher than silicon (Z>14). The Bruker AXS instrument is capable of potassium (Z=19) and higher, whereas flushing with helium allows for detection of elements down to Al (Z=13). Where possible, a sample was prepared as cross-sections for characterisation of the preparation layers and inorganic pigments using LM and SEM/EDX that provided data on the optical characteristics of the materials and spatially resolved elemental analysis. This could be used to interpret data obtained using the non-sampling analytical methods. Layer-specific characterisation of the painted works was limited by the opportunity to take samples whilst the works on paper provided no opportunity for sampling. The results of the study of this group of works are described more fully in a forthcoming exhibition at the Courtauld Gallery and the accompanying exhibition catalogue The Courtauld Cézannes (Reissner 2008). This paper focuses on the practical aspects of the analytical 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