Materials science challenges in radiocarbon dating: The case of archaeological plasters

Structural, compositional, and isotopic characterization techniques are critically important to help identify pristine materials that are suitable for accurate and precise radiocarbon dating. Lime plasters, cements, and mortars are ideal materials for establishing firm and secure dates in the archaeological record as human-constructed living surfaces and installations. However, the often complex composite structures of plasters and their susceptibility to diagenetic processes have impeded the development of a reliable and reproducible method to identify the best specimens for dating. In this article we present an overview of the plaster production process and the radiocarbon dating method. We explain how material characterization techniques and radiocarbon dating can be integrated to make progress toward the ultimate goal of relating radiocarbon concentrations with environmental, sample preparation, and/or diagenetic conditions in which the plaster existed. A key aspect of this strategy relies on implementing material characterization techniques in the field, during an excavation, to help establish the archaeological context in which datable material is recovered.