Contamination in Organic Residue Analysis: A Cautionary Tale

The excitement of finding ceramic materials on an excavation often leads to questions of function and use that can affect the final interpretation of a site. Organic residue analysis (ORA) is commonly used in determining artifact function. ORA requires collaboration between an archaeologist and chemist in the analysis of the materials. But, the significance of sampling methods is often understated. In addition, the various instruments used to perform the analysis are often seen by the archaeologist as infallible and the data believed to be easily interpretable. This article presents a case study that highlights the role of selectivity in ORA and cautions the reader against generalized interpretations that can provide false positives.