AIC 53rd Annual Meeting

Red-figure pottery is a type of ancient Greek ceramic that originated in Athens in the later 6th century B.C. It typically features decoration in diluted clay slip that turns black after firing and is painted on a clay body that appears reddish orange. This kind of ware was used in daily life, dedicated in sanctuaries, and placed in tombs. The “red” areas contain hematite (Fe2O3), and the black background contains magnetite (Fe3O4) and hercynite (FeAl2O4). The red and black designs of Attic pottery have been shown to result from a complex firing process involving cycles of oxidation, reduction, and reoxidation. Initially, fine-grained red hematite is reduced to a dense, vitrified layer of black magnetite and hercynite, which resists reoxidation. In the final oxidation step, only the coarse-grained, porous ceramic body reoxidizes to red hematite, creating a sharp contrast between the red figures and the glossy black background (1–3).  

The Harvard Art Museums house an impressive collection of Athenian red-figure pottery. This includes the focus of this study, the so-called Bouzyges krater (1960.345), a 5th century B.C. mixing bowl for wine and water, named after the protagonist of the mythological scene depicted on its front. Although there are areas of well-preserved red-figure decoration on the krater, other areas display various levels of discoloration. The pronounced differences between adjacent sherds suggest that some alterations occurred after the vessel was broken, likely due to its involvement in a cremation burial. In such burials, ceramic vessels, often used as grave goods, were likely thrown onto the pyre and then swept into the burial, leading to the discoloration seen on the krater. Funeral pyres can reach temperatures up to 1000 ⁰C, creating a partly reducing environment due to the evolution of carbon monoxide and dioxide from burning bodies (4). It is to be expected that the temperature and oxidation/reducing environment will vary across the pyre, causing the broken fragments to display different degrees of discoloration. On some fragments, the red ceramic is altered into grey due to the reduction of hematite. On others, the black gloss is partially altered into red, suggesting high-temperature oxidation of the iron oxides occurred in areas of the fire where oxygen was more abundant.  

The disassembly of this vessel as part of its conservation treatment provides an ideal opportunity to study the krater, shedding light on the high-temperature material changes observed from the surface of the slip to the bulk of the ceramic. Using techniques such as SEM-EDS, X-ray diffraction, Raman, and FTIR spectroscopy, this material study will be important for the conservation of similar ceremonial vessels, furthering our understanding of their involvement in ritualistic practices. 

References 

1. R. Jones, Adv. Archaeomaterials. 2, 67–127 (2021). 

2. M. Walton et al., J. Am. Ceram. Soc. 96, 2031–2035 (2013). 

3. S. Balachandran, Arts. 8, 70 (2019). 

4. M. S. Walton, M. Svoboda, A. Mehta, S. Webb, K. Trentelman, J. Archaeol. Sci. 37, 936–940 (2010).