G. Bultrini

Microchemical study of the black gloss on red-and black-figured Attic vases

The microchemistry of the black gloss decoration layer on black- and red-figured Attic vases (6th to 4th century BC) has been studied by means of selected-area x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS). The results show that the Attic black gloss is obtained from an illitic clay, enriched in iron oxide particles, that is applied on the vase body and fired in an oxidizing-reducing-oxidizing cycle at a top temperature of ∼950°C, Furthermore, the results disclose the presence in the black gloss of iron grains with a complex structure, constituted by discrete areas of single phases with Fe 3+ , Fe 2+ and Fe°. These particles are finely dispersed in a vitreous Al-K- and Fe-enriched silicate where also Fe-C and C-C carbon atoms are present. The information about the raw materials and the firing process shows that the production of Attic vases is important for the history of the art as well as of the ceramic technology.

Microchemical study of the corrosion products on ancient bronzes by means of glow discharge optical emission spectrometry

Glow discharge optical emission spectrometry (GDOES) has been used for studying the corrosion product layers, i.e. the patinae, on Punic bronze artefacts found at Tharros (western Sardinia, Italy) during an archaeological excavation. For all these materials, the results show that via GDOES it is possible to obtain reliable and reproducible quantitative chemical composition for the bulk alloys by taking into account that bronze artefacts are quite inhomogeneous. Some examples of the GDOES analytical capability as elemental depth-concentration profiles through thick bronze patinae are shown and briefly discussed in combination with the microchemical features obtained via scanning electron microscopy/energy dispersive spectrometry (SEM+EDS) and x-ray diffraction (XRD). These results show that GDOES, with its ability for routine and rapid analysis of layers of thickness up to 120 μm, has significant potential in studies of the corrosion products and for the restoration and conservation of ancient bronzes.