Tradition unveiled. Pottery production in the Brazilian Kadiweu culture

The ceramic bowls production of the Brazilian Kadiweu culture (Rio Nabileque, Mato Grosso do Sul), currently belonging to Museo delle Civiltà (MUCIV) – Museo Nazionale Preistorico ed Etnografico “Luigi Pigorini” in Rome, were studied for the first time by a multi-analytical investigation at Istituto Centrale per il Restauro (ICR, Rome). Optical microscopy on thin section (OM) and X-ray Powder Diffraction (XRPD) were used to characterize two Kadiweu bowls (raw materials, firing and production process). UV observation and micro-Fourier Transform Infrared Spectroscopy (µ-FTIR) were used to characterize either original or former restoration products. Finally, X-ray images were taken to study the modelling technique. This minimally invasive approach showed that raw materials and technology are compatible with local production. The use of grog was documented for the paste, which was then fired at moderately high temperatures. This study also led to revise some ethnographic data on decorations, at least for the analysed bowls, such as the use of kaolin as white pigment, which was instead proven to be calcite, or the origin of the traditional black dye from pau santo, a local tree. Its spectrum was for the first time collected on ceramics and identified as guaiac resin, which possibly comes from Guaiacum sanctum or officinale. This research project also allowed the identification of two different restoration activities, with two types of adhesives: shellac and animal glue, the latter used with lithopone. Paraloid B72 was also identified as a protective layer. Finally, textile materials found on the artefact were also characterized.