COLONIAL ART. CHARACTERIZATION OF AN XVII CENTURY POLYCHROME SCULPTURE

EUGENIA TOMASINI; GABRIELA SIRACUSANO; MARTA MAIER

Barcelona

Congreso; 10th Biennial International Conference of the Infrared and Raman Users Group (IRUG10); 2012

Universitat de Barcelona

The image of the Virgin of Copacabana is a gilded polychrome sculpture manufactured in maguey wood at the end of the XVI century. It is a highly devotional image in the Andean region and her sanctuary lays at the Titicaca Lake in Bolivia. Like other South American polychrome sculptures, it was produced during the so-called Colonial period as part of the process of evangelization done under the Spanish domain [1]. In this study, we have analyzed a green sample taken from the Virgin´s cloak. The green pigment layer covered completely the shiny color of the gilded area. A pattern of geometrical motifs was brought to light from the gilded area with the help of a sharp point. The aim of our study was to identify the green pigment and the gilding technique. First, the cross section of the sample was examined by optical microscopy revealing the presence of green crystals on a white layer. Beneath it a gold leaf on a read bole was observed. SEM-EDX analysis of each layer allowed the identification of copper as the green pigment and lead in the white layer. Analysis by micro-Raman spectroscopy (Figure 1) indicated the presence of atacamite (Cu3Cl2(OH)3) as the green pigment. This compound has been identified as a degradation product of copper pigments or of metallic objects containing copper [1-3]. Figure 1. a. atacamite, b: cerussite, c: hematite, d: gypsum The white pigment containing lead was identified as cerussite by micro-Raman spectroscopy while hematite was the component of the bole and gypsum was used as the preparation layer. REFERENCES 1. Dei, L.; Ahle, A.; Baglioni, P.; Dini, D. and Ferroni, E. Green degradation products of azurite in wall paintings: identification and conservation treatment. Studies in Conservation (1998) 43, 80-88 2. Frost, R.; Martens, W.; Kloprogge, T. and Williams, P. Raman spectroscopy of the basic copper chloride minerals atacamite and paratacamite - implications for the study of copper, brass and bronze objects of archeological significance. Journal of RamanSpectroscopy(2002), 33, 801-806. 3. Scott, D. A review of copper chloride and related salts in bronze corrosion and as pigments. Studies in Conservation (2002) 45, 39-53.