A MULTIANALYTICA APPROACH TO THE PAINTING TECHNIQUE AND THE GREEN AND BLUE PIGMENTS USED IN ANDEAN COLONIAL WALL PAINTINGS

EUGENIA P. TOMASINI; FERNANDO GUZMÁN; CARLOS RÚA; MARTA S. MAIER; VALERIA P. CAREAGA; GABRIELA SIRACUSANO

Bilbao

Congreso; Technart 2017 International Conference. Non-destructive and microanalytical techniques in art and cultural techniques; 2017

Universidad del Pais Vasco

A multi-analytical approach to the painting technique and the green and blue pigments used in Andean colonial wall paintings Eugenia Tomasini(1), Valeria Careaga(1), Carlos Rúa Landa(2), Fernando Guzmán(3), Gabriela Siracusano(4) and Marta Maier(1,4)(1)1Universidad de Buenos Aires. Unidad de Microanálisis y Métodos Físicos Aplicados a la Química Orgánica (UMYMFOR), CONICET. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica. Pabellón 2, Ciudad Universitaria, (C1428EGA), Ciudad Autónoma de Buenos Aires, Argentina. (2)Ministerio de Culturas y Turismo, Taller de Conservación y Restauración del Patrimonio Mueble, La Paz, Bolivia. (3)Centro de Estudios del Patrimonio, Universidad Adolfo Ibáñez, Santiago de Chile, Chile.(4) Centro de Investigación en Arte, Materia y Cultura (IIAC), Universidad Nacional de Tres de Febrero, Avenida Antártida Argentina 1355 (C1104ACA), Ciudad Autónoma de Buenos Aires, Argentina. This work shows the results of the application of different analytical techniques to characterize the green and blue pigments and investigate the painting technique in Andean colonial wall paintings. Studies were carried out on microsamples extracted of murals from the churches of Soracachi, Curaguara de Carangas, Corque, and Santiago de Callapa in Bolivia. These colonial churches were located on an ancient commercial road linking the cities of Potosí in Bolivia with Arica in Chile, known as the Silver Route (S.XVI-XVIII). To approach these goals, an integrated investigation comprising Raman and FTIR-ATR spectroscopy, optical microscopy, scanning electron microscopy with X-ray spectroscopy (SEM?EDS), and mass spectrometry (MS) was carried out. The study revealed a very simple painting technique consisting on the application of a thin pigment layer on a white ground layer on the adobe wall. Previous investigations on the wall paintings of the church of Our Lady of Copacabana de Andamarca in Bolivia indicated a secco technique [1]. The Raman analysis of the ground layer in the cross-sections of the samples showed characteristic bands of calcium sulfate compounds with different levels of hydration: gypsum, basanite and anhydrite [2]. Regarding the green pigments, Cu-based minerals, such as brochantite and antlerite, both basic copper sulfates, were identified in most of the green samples. These pigments are uncommon in colonial art and have been recently reported in a wall painting of a church in Bolivia [1]. Among the blue pigments, indigo was identified by micro-Raman spectroscopy and direct insertion mass spectrometry [3]. This MS technique also gave information on the binder mixed with the blue pigment. The characterization of the materials used in the manufacture of the wall paintings together with the pictorial technique constitutes a significant contribution to the study of the Andean artistic heritage, which is in many cases the result of the fusion of pre-Columbian knowledge with practices of European painting.[1] E. Tomasini, D. Castellanos Rodríguez, B. Gómez, D. de Faria, C. Rúa Landa, G. Siracusano, M. Maier, Microchemical J. 128, 2016, 172. [2] N. Prieto-Taboada, O. Gómez-Laserna, I. Martínez-Arkarazo, M.A. Olazabal, J.M. Madariaga, Anal. Chem. 86, 2014, 10131.[3] B. Gómez, D. Castellanos Rodríguez, V. Careaga, G. Siracusano, M. Maier, Microchem. J. 125, 2016, 21.