One of the greatest barriers to accurate and reliable radiocarbon dating of archaeological materials in museum or archival collections is the presence of materials introduced during conservation treatment, consolidants. Focussing on wood and bone primarily, this project will investigate how effectively existing pretreatment methods remove these sources of contamination, and it will also examine the potential of novel thermal decomposition and isotope methods for improved isolation of reliable material for radiocarbon dating. Preservation of organic archaeological artefacts is a critical task that often involves the application of a variety of consolidants by conservators. With subsequent aging these consolidants become absorbed into the fabric of the artefact and potentially become chemically bound. Removal of these sources of contamination is critical as a part of radiocarbon dating, as otherwise the age estimation can be skewed younger or older dependent on the age of the consolidant itself. Chemical methods to remove these consolidants are typically focussed around a Soxhlet-based approach, however numerous studies suggest this is not always successful and often where the method is applied there is a lack or definitive support for complete removal of the consolidant. Recent applications of thermal decomposition techniques (ramped pyrolysis/oxidation, RPO) have demonstrated a potentially useful new approach for isolating more reliable fractions of CO2 from consolidated artefacts. This method exploits the different thermal decomposition temperatures between the material of interest (e.g. wood cellulose) from a typical consolidant (e.g. polyethylene glycol) to minimize sources of contamination. In tandem with analytical techniques such as fourier transform infrared spectroscopy (FTIR) and stable isotope analysis, the thermal decomposition profiles and radiocarbon dating characteristics of different thermal fractions can also be used to better validate how “clean” the sample is and develop improved treatment methods. This project will thus enable enhanced dating methods for existing archaeological artefacts, and also has the potential to facilitate developing enhanced conservation methods for archaeological artefacts. This project will examine the effectiveness of existing and novel pretreatment approaches in the removal of consolidants and the isolation of reliable material for radiocarbon dating. This will include exploring the potential of stable isotope analysis (δ13C) as a screening and validation method via a recently established RP-IRMS system at 14CHRONO.
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