‘Seeing shit’: assessing the visibility of dung tempering in ancient pottery using an experimental approach

Widespread ethnographic evidence exists for the addition of animal dung to clay during the process of ceramic production. However, conclusive evidence of dung tempering in archaeological ceramics is relatively rare. The aim of this study is to ascertain whether, and under which conditions, dung tempering of pottery is identifiable. To answer these questions, we assessed whether a combination of micro-particle analysis in loose sediment and thin-section petrography can reveal the addition of dung to the clay paste by focusing on faecal spherulites, ash pseudomorphs, phytoliths and coprophilous fungal spores. We analysed several series of experimentally produced ceramic briquettes tempered with different types of dung and dung ash, which were fired at a range of increasing temperatures. Our study shows that the identification of dung tempering represents a challenge, and it depends on a number of different factors, among others the original presence of dung markers in the dung used, the manufacturing process, the firing temperatures and the firing atmosphere. Overall, through a multidisciplinary approach, our work clarifies a variety of issues connected to the identification of dung in ancient pottery, highlighting the role of faecal spherulites as the most promising proxy.