Raman and FT-IR spectroscopy of prefiring paintings and slips in pre-Hispanic South American pottery—the case of Diaguita Inca pottery: an initial glazing-painting process? (Tinogasta, Catamarca, Argentina)

Abstract

Diaguita Inca pottery is present in some Inca archaeological sites at Northwestern Argentine region. It is an imported pottery coming from Chile, and it belongs to the last phase (phase III) of Diaguita culture (Ampuero 1986). This last phase corresponds to Inca rule period, immediately prior to Spanish arrival to America (ca. fifteenth to seventeenth century) (Cornely 1962). Diaguita pottery is profusely decorated, presenting a marked polychromy. Red, white, black and brown prefiring colours were used by ancient potters to paint different motifs and patterns (Cornely 1962). Red and black colours are usually over a regularly well-formed white slip. Ceramic iconography, visual art and decorative patterns during the Diaguita Inca phase in this pottery have been extensively studied by González Carvajal (2013). Typical vessel forms during Diaguita Inca (phase III) are bowls, arybalous, duck plates, shallow plates and urns (Cornely 1962; González Carvajal 2013). Several samples of Diaguita Inca pottery were selected for this research (Online Resource 1, Figs. S1 and S2). Samples have been extensively mineralogically, chemically and technologically studied elsewhere (De La Fuente et al. 2015; Vera et al. 2019). Online Resource 2 (Table S1) gives the main characteristics for this pottery. Microstratigraphic and surface paintings samples of Diaguita Inca (ca. 1480–1600 CE) archaeological pottery found in Tambo Costa de Reyes N° 5, an Inca site geographically located at southern Abaucán Valley (Department of Tinogasta, Province of Catamarca, Argentina) (Online Resource 1, Figs. S3 and S4) (Vera et al. 2019), were studied by optical and petrography microscopy, and the identified strata were analysed by micro-Raman spectroscopy, micro-FT-IR and scanning electron microscopy with elemental analysis by energy dispersive X-ray spectroscopy (SEM-EDS).