2009 International Nuclear Atlantic Conference - INAC 2009 Rio de Janeiro,RJ, Brazil, September27 to October 2, 2009 ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABEN ISBN: 978-85-99141-03-8 X-RAY FLUORESCENCE AND COMPUTED RADIOGRAPHY ANALYSIS OF A FAMOUS BRAZILIAN PAINTING FROM THE XIX CENTURY Cristiane Calza1, Davi F. Oliveira1, Henrique S. Rocha1, Andrea Pedreira2 and Ricardo Tadeu Lopes1 1 Laboratório de Instrumentação Nuclear – COPPE/UFRJ Caixa Postal 68509 21941-972 Rio de Janeiro, RJ [email protected] 2 Museu Nacional de Belas Artes Rio de Janeiro, RJ ABSTRACT This work used Energy Dispersive X-Ray Fluorescence (EDXRF) and Computed Radiography (CR) to evaluate the general conditions of the painting “Gioventú” (Eliseu Visconti, 1898), identifying possible problems, areas that revealed signs of previous retouchings and the pigments used by the artist. EDXRF measurements were carried out with a portable system consisting of an X-ray tube Oxford TF3005 with W anode, operating at 25 kV and 100 µA, and a Si-PIN XR-100CR detector from Amptek. Several spectra were obtained in each color, with an acquisition time of 300 s and a beam collimation of 2 mm. The spectra were analyzed using the software QXAS-AXIL (IAEA). The results revealed that the drawings were made over a preparatory layer of lead white. Some pigments identified were: yellow, red and brown ochre; umbra; vermilion; cobalt blue; etc. The experimental setup used in the CR analysis consisted of an Oxford X-ray source, operating at 50 kV and 200 µA, placed at 85 cm from the painting, a GE CR 50P Portable Computed Radiography Scanner and a Fuji Imaging Plate detector. The exposure time was 600 s. The radiographic images revealed that the painting was in a good state of conservation and also a complete composition hidden underneath the visible paint layer. 1. INTRODUCTION The scientific examination of artworks has gained increasing interest in the last years, allowing the characterization of materials and techniques employed by the artists. This analysis can be extremely valuable to conservation and restoration treatments. It can also supply important information that makes possible to identify an artist, to date a painting and to identify forgeries. However, the fact that every artwork is a unique piece emphasizes the necessity of working with non-destructive techniques [1-3]. This work used Energy Dispersive X-Ray Fluorescence (EDXRF) and Computed Radiography (CR) to analyze one of the most famous Brazilian paintings from the ending of the XIX century, belonging to the National Museum of Fine Arts Collection. “Gioventú” (oil on canvas, 65 x 49 cm) was executed by Eliseu Visconti in 1898. These techniques were used to evaluate the general conditions of the painting, identifying possible problems, areas that revealed signs of previous retouchings and the materials employed by the artist. In the figure 1 it is shown the analyzed painting. Eliseu d’Angelo Visconti (1866-1944) was born in Italy and, still in childhood, he moved to Brazil with his parents, where he was naturalized in 1890. In 1884, he was admitted at the Imperial Academy of Fine Arts, studying with the masters Victor Meireles, Henrique Bernardelli and Rodolfo Amoedo. In 1892, he won the Europe Travel Prize and traveled to Paris, attending at the École des Beaux-Arts, Académie Julian and École des Arts Décoratives, where he was pupil of Eugène Grasset. He won a silver medal in the Universal Exhibition of Paris, in 1900, with the paintings “Gioventú” and “Oreades”, and a gold medal in the International Exhibition of St. Louis (USA), in 1904, with the painting “The Recompense of Saint Sebastian”. Visconti is considered as the bridge between the XIX and the XX centuries, since he was, even in a late way, the pioneer of the Impressionism in Brazil, inspiring several pre-modernist painters, without cutting himself off the XIX century formal influences, as exemplified by the Realist element in his works [4]. Figure 1. “Gioventú”. Eliseu Visconti, 1898. Oil on canvas, 65 x 49 cm. National Museum of Fine Arts. Rio de Janeiro, Brazil. INAC 2009, Rio de Janeiro, RJ, Brazil. X-Ray Fluorescence analysis is a widely used spectroscopic technique in archaeometry to investigate the composition of pigments (in manuscripts, paintings, ceramics and other artifacts), metal alloys, coins and statuary. It is a non-destructive technique to make possible qualitative and quantitative multielemental analysis with good precision and accuracy [1,5]. The most recent developments in X-ray tubes and detectors have led to the introduction of small and portable instruments, which can be used for the in situ analysis of cultural objects in museums and galleries [6]. The analysis of the pigments used in a painting is important for many reasons. The first is the possibility of evaluate the artist working method: which pigments were used, in such way these pigments were mixed to create a specific coloring, and also, which pigments were used in the preparatory layer. This analysis is also extremely important for restoration procedures, since it can helps to distinguish the original regions from retouchings or later added ones. Thus, pigment characterization may be crucial to important decisions such as those regarding the removal of spurious layers or the choice of the most suitable pigment for retouchings. A third purpose is related to conservation: because some pigments may be affected by environmental conditions, a painting may require specific practices for storage and/or exhibition. In addition, the pigments identification can be necessary before applying chemical treatments to reverse or to stop deterioration processes. Finally, since the chronology of pigments use is well-known, is possible to establish the provenance, historical period and, consequently, the authenticity of a painting [7-9]. Radiographic techniques have been used in museums to study archaeological artifacts, in order to reveal internal details that would otherwise be invisible. In paintings, radiography can reveal the extent of old damages concealed by restoration procedures; the successive phases of the artist’s creation (preparatory drawing, underpainting and changes of design); the nature of the support; the canvas weave; presence of lead pigments, nails and changes in the original surface topography (caused by drying of the ink, like cracking and detachment, and changes in the fabric). X-rays are attenuated differently by the various areas of the painting depending on several factors including the energy of the radiation; density, thickness and composition of the paint layer; and the elemental composition of the support elements (ground, canvas, stretchers, etc.). High Z elements absorb X-rays more efficiently than low Z elements, consequently, pigments that contain elements like Pb, such as lead white or lead-tin yellow, absorb more radiation and appear as light areas on the images. Other pigments, like ochre, for example (that contains Fe), and crackings, do not absorb as many X-rays and appear as dark areas [10-12]. 2. EXPERIMENTAL The experimental setup used in the Computed Radiography of the painting “Gioventú” consisted of an Oxford X-ray source, operating at 50 kV and 200 µA, placed at 85 cm from the painting, a GE CR 50P Portable Computed Radiography Scanner and a Fuji Imaging Plate detector. The IP detector (35 x 43 cm) was fixed behind the canvas to perform each radiograph, using an exposure time of 600 s. The images were revealed by introducing the exposed IP in the scanner, which also erased the film after the image processing. Finally, the four radiographs obtained to the canvas were connected, by means of appropriate software, to compose the radiograph of the whole painting, which can be observed in the figure 4. INAC 2009, Rio de Janeiro, RJ, Brazil. The EDXRF analysis was carried out with a portable system developed in the Nuclear Instrumentation Laboratory, consisting of an Oxford TF3005 X-ray tube and a Si-PIN XR- 100CR detector from Amptek (with 6 mm2 active area and a 25 µm Be window). The X-ray tube presents a tungsten (W) anode, a 127 µm Be window and maximum operating current and voltage of 0.5 mA and 30 kV, respectively. The angle between the X-ray tube and the detector window is 60°, the source-sample and the detector-sample distances are 4 cm. The system is adapted to a tripod, which makes possible to reach higher regions during the analysis of paintings and statues. In each color and different hue in the painting were obtained several spectra, working at 25 kV and 100 µA, with an acquisition time of 300 seconds and a beam collimation of 2 mm. The spectra were analyzed using the software QXAS-AXIL, from IAEA. 3. RESULTS AND DISCUSSION 3.1. Computed Radiography analysis The radiographic images revealed that the painting was in a good state of conservation. Only small regions of loss of paint support could be observed: the more significant, over the left shoulder of the portrayed girl and the others at the right and left sides of the canvas, near to the frame. These regions appear as black areas in the canvas, since they allow X-rays to pass through them, darkening the Imaging Plate fixed behind the canvas. The figures 2 and 3 show details of two regions of loss of support. Figure 2. Detail of the radiograph: region of loss of support (dark area) located in the left shoulder of the girl. The canvas weave can be also observed. INAC 2009, Rio de Janeiro, RJ, Brazil. Figure 3. Detail of the radiograph: regions of loss of support (dark areas) located in the right side of the painting, near to the frame. The canvas weave can be also observed. The radiographs also revealed some details such as the canvas weave and the stretching marks, originated when the fabric was fixed on the wooden support.