Caput mortuum: spectroscopic and structural studies of an ancient pigment

Abstract

The use of a pigment variously described as caput mortuum, usta or ostrum to provide a deep purple colour in ancient wall-paintings was highly prized, despite the technical difficulties associated with its application. With the Raman spectroscopic characterization of pigments in ancient frescoes and wall-paintings becoming more widespread, it is timely to consider the identification of this material either as a generic haematite alone or in admixture with contemporary blue pigments. Here, Raman and infrared spectroscopic, X-ray diffractometric and scanning electron microscopic structural studies have been undertaken to characterize caput mortuum and to identify a specimen of Roman wall-painting dating from the 3rd century.

Atomic resolution studies detect new biologic evidences on the Turin Shroud

“…Indeed, ancient dye pigments are, in general, on the scale of hundreds of nm [36]. Even if painting dyes of few nanometers had been used, they would be not well dispersed inside big nanoparticles, as observed in our experiments (see Fig 3 and S2 Fig), but they would tend to aggregate each other [37].…”

Raman microscopy in archaeological science

“…Aside from the reconstructions of pottery firing conditions already mentioned, this area of research has concentrated on understanding the technology used in the production of artists' colours [30,36,108]. For instance, resonance Raman spectroscopy was used to investigate the effects of synthesis conditions on the final colour and properties of a historic pink porcelain glazing pigment, a chromium-doped tin-based sphene, used at the famous French Sevres Factory [81].…”

Heated goethite and natural hematite: Can Raman spectroscopy be used to differentiate them?

“…Reports dating from Roman times indicate that a variety of different shades of yellow and red could be obtained simply heating goethite (a-FeOOH) [6,7]. Goethite (a yellow compound) turns into hematite (a-Fe 2 O 3 ), which is red, at relatively low temperatures (ca.…”