NANOSCALE MICROSTRUCTURE AND MINERALOGY OF A GREEK VASE: CHARACTERIZATION OF BLACK AND RED GLOSS USING FIB/STEM, ESEM/EDS AND ELECTRON MICROPROBE ANALYSIS

Ceramics were the “high technology” material of Ancient Greece, used to produce popular drinking vessels and exotic works of art. This work seeks to characterize these understudied materials using methods such as FIB/STEM, which show promise for the nanoscale sampling and investigation of works of art. Preliminary chemical analyses of samples from Attic Greek vases often showed similar chemical composition for the red gloss and the black gloss, which are fired illite clay slips about 20 microns thick. Further analysis using the electron microprobe showed significant differences calcium and magnesium concentration between some red and black layers. FIB/STEM was used to evaluate the porosity and nanoscale structure of the two layers using representative samples of black and red gloss. The results show that the black layer is a dense glass containing 20-250 nm scale grains of magnetite-maghemite, hercynite and illmenite while the red is a more oxidized, sintered material, with ~20% porosity, containing remnant clay structures and hematite grains. The higher calcium and magnesium concentration in some red gloss layers appears to increase the melting temperature of the material, resulting in an open, sintered texture. Interestingly, the red gloss method was only used for about 200 year period starting in Athens in about 530 BC, perhaps due to its more vulnerable nature, being less firmly bonded to the ceramic substrate.