INTEGRATED ANALYTICAL TECHNIQUES FOR THE CHARACTERIZATION OF PAINTING MATERIALS IN TWO SOUTH AMERICAN POLYCHROME SCULPTURES

In this study, we present work on two sculptures producedin the Jesuit Missions in Paraguay in the 18th century. Acombination of analytical techniques was applied for thecharacterization of pigments and plasters. First, cross-sectionsof the samples were examined by optical microscopyand SEM-EDX. Then, application of transmitted FTIR spectroscopyfor selecting samples confirmed the presence ofgypsum (Ca2SO4.2H2O) used as the preparation layer.Copper resinate was identified in one of the sculptures bya combination of FTIR, SEM-EDX and gas chromatography,together with its characteristic colour as obser ved in thecross-sections of the samples. The red pigments were identifiedas vermilion, hematite and minium, together with theorganic pigment madder lake identified by HPLC-DAD in oneof the sculptures. All these chemical results become moresignificant and relevant when we considered them in lightof the results obtained from research on historical documentsand old treatises used in the region.