Characterization of pigments and binders in a mural painting from the Andean church of San Andrés de Pachama (northernmost of Chile)

JOSÉ CÁRCAMO; SEBASTIÁN GUTIÉRREZ; FERNANDO GUZMAN; MARTA S. MAIER; DIANA M. CASTELLANOS RODRÍGUEZ; CARLOS RÚA LANDA; MAGDALENA PEREIRA; EUGENIA P. TOMASINI; VALERIA CAREAGA; MARCELA SEPÚLVEDA; GABRIELA SIRACUSANO

Heritage Science

SpringerOpen

Lugar: New York; Año: 2018 vol. 6 p. 1 - 12

2050-7445

The Andean church of San Andrés de Pachama is located at 3423 masl in the northernmost of Chile, near the limit with Bolivia and the so-called Silver Route. The walls inside the church are decorated with paintings dated from the 18th century depicting religious motifs as well as decorations of flowers, fruits, and birds. In this study, eight samples taken from one of the mural paintings have been analysed with the aim to identify the pigments and binders and investigate the painting technique. Analysis by micro-Raman spectroscopy complemented with scanning electron microscopy?energy dispersive spectroscopy (SEM-EDS), attenuated total reflection infrared spectroscopy (FTIR-ATR), X-ray diffraction (XRD), and high-performance liquid chromatography (HPLC) allowed the identification of orpiment, vermilion, indigo, smalt, antlerite, hematite, carmine lake, and a carbon-based black pigment as well as gypsum as the ground layer. Analysis of the organic binders by gas chromatography mass spectrometry (GC-MS) and observation of the cross-sections of the microsamples by optical microscopy indicated a secco technique and the use of egg and vegetable oil as the pigment binder (tempera grassa). Smalt and cochineal are reported for the first time in an Andean colonial mural painting.