Archaeometric Study of Pictorial Stratigraphies from a Togatus Roman Sculpture found in Salamanca (Spain)

Abstract

The decoration of a togatus Roman sculpture found in Salamanca in 2015 has been examined to identify the applied pigments. The study was performed using environmental scanning electron microscopy –ESEM– with an energy-dispersive X-ray analyser –ESEM-EDX– and Raman spectroscopy –RS– in microscopic mode. The ESEM-EDX analyser allowed the elemental chemical composition of the samples to be established, the concentration and distribution of each element in areas and cross-sections to be determined, and predefined concentration profiles in the pictorial stratum to be obtained. The ionic or molecular phases of the components in the pictorial material were identified by Raman spectroscopy. Therefore, the pigments that make up the pictorial palette of this artwork, such as iron oxides or carbon black, have been ascertained by means of these complementary techniques. The structural substrate, as well as the chemical nature of the dispersing/priming materials for the colourants, have been additionally characterised. Silica and aluminosilicates have been found to be present in combination with both the iron oxides and carbon black.