Layers of Meaning: Absorbed residue formation and interpretation

Absorbed pottery residues are organic residues formed in part through absorption of compounds from pot contents into the ceramic matrix of a vessel. Overall formation of these residues is complex and multi-layered, and interpreting them is not unlike excavating a site. Some compounds may be persistent soil lipids that survived low-temperature pottery firing, or pyrolytically formed compounds from such soil lipids. The compounds from archaeological use represent an aggregate of all or most of the pots uses over its lifetime. Then, upon deposition, compounds wash out of the pot, hydrolyze, and oxidize, while some soil contaminants may wash into the organic residue. During excavation, excavators touch and process the pot, introducing modern sources of contamination. How do we distinguish between modern contamination, soil contamination, pyrolytically formed compounds, breakdown products and compounds contributed by archaeological vessel use? A good understanding of soil chemistry, pyrolytic chemistry, the experimental literature, and the composition of modern sunscreens and bug sprays is essential in making these distinctions. We discuss these issues through case studies and discussion of experimentally produced residues. With careful attention to context and chemistry, a vessel’s use and quite a bit of its subsequent history can be interpreted from absorbed residues.

Layers of Meaning: Absorbed residue formation and interpretation Presentation