Raman microspectroscopic analysis of decorative pigments from the Roman villa of El Ruedo (Almedinilla, Spain)

Abstract

In this work, we analysed the preparatory layer and paintings in the hypocaustum of the Roman villa of El Ruedo (Almedinilla, southern Spain). The specimens studied were from the III and IV centuries. Raman microscopy was for the first time used here to examine Roman pictures in the south of the Iberian peninsula. The results obtained allowed us to establish the chemical nature of the different pigments used by the Roman artists. All were applied over a preparatory layer consisting of limewash. The different colours used (black, white, red, yellow, green and blue) were obtained by using carbon, calcite, gypsum, hematite, goethite, green earth and Egyptian blue. Some exhibited various hues that were obtained by mixing the previous compounds. Worth special note is the incipient presence of blue pigments, which were rarely used in Roman Hispania owing to their scarcity and high price.

Keywords: Archaeological pigments; Egyptian blue; Hematite; Raman spectroscopy.