Integrated analytical techniques for the characterization of painting materials in South American polychromy

M. MAIER; B. GOMEZ; S. PARERA; G. SIRACUSANO

VIENA, AUSTRIA

Congreso; The eighth biennial conference of the Infrared and Raman Users Group; 2008

Infrared and Raman Users Group-Academy of Fine Arts

We used several analytical techniques to identify pigments and plaster layers. First, cross sections of the samples were examined by optical microscopy and SEM-EDX. Then, application of transmitted FT-IR spectroscopy to selected samples confirmed the presence of gypsum, Ca2SO4.2H2O, as the plaster in all sculptures except in one of them where chalk, CaCO3, was identified. This is an indication of the application of technologies transmitted by German and Austrian masters in this region. Green earth, identified by a band around 1014 cm-1 and its characteristic elemental composition by SEM-EDX was the green pigment most used in the manufacture of these sculptures. Copper resinate was identified in two sculptures by a combination of FT-IR, SEM-EDX and gas chromatography together with its characteristic color as observed in the cross sections of both samples. Other pigments identified in the sculptures were Prussian blue, vermilion, hematite and lead white.