Spectroscopic, morphological and chemical characterization of historic pigments based on carbon. Paths for the identification of an artistic pigment

Abstract

Analytical characterization of reference carbon-based black pigments has been performed using Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance (ATR) and scanning electron microscopy (SEM) coupled to an energy-dispersive X-ray spectrometer (EDS). The unambiguous identification of these pigments, which are found in paintings, rock art and archeological artifacts, still remains a big challenge due to the variety of sources and manufacturing processes used in their preparation. The analytical results achieved in this study allowed us to discriminate between carbon-based pigments from different sources and detect adulterations. The methodological approach was successfully applied to the identification of vegetable charcoal and bone black in two colonial paintings dated from the eighteenth century. Conclusions regarding the pictorial techniques were drawn from FTIR data.