Organic Residue Analysis: Views from the Field

By: Zuzana Chovanec, Susanne Grieve, Laura Mazow

Organic Residue Analysis (ORA) from archaeological materials offers exciting prospects for researchers into how objects have been used by past cultures. While ORA is not a new presence in archaeology, developing technologies have made instrumentation more accessible and new collaborations between archaeologists, analytical chemists, and even conservators demonstrates the interdisciplinary nature of the subject. Those who are involved in ORA generally come from one of the following perspectives:

• Chemist who is working with archaeologists
• Archaeologist who is working with chemist
• Archaeologist who trained to be an analytical chemist

In any collaborative research environment, each specialist brings a strength to the topic, but ORA raises the issue of what depth of understanding each specialist should have in the other’s field in order to facilitate effective communication of the research questions and priorities.  In order to better understand these perspectives, the authors each compiled some thoughts on their perspectives from their respective fields:

What is important for archaeologists to know when they think ORA can benefit their research question?

(Chovanec) Archaeologists tend to be a progressive group, always looking for innovative approaches that can better inform and interpret their datasets. The explanatory potential of organic residue analysis can generate enthusiasm because it opens inquiry to a series of questions that may be minimally approachable using traditional archaeological methods. Archaeologists interested in incorporating ORA into their research programs should familiarize themselves with both the possibilities and limitations and have a basic understanding of the costs and timelines involved.

When trying to establish a collaborative research program between archaeologists and chemists, an effective approach is to develop research questions that interest and benefit both parties. For instance, chemists whose research involves the development of new analytical techniques may be interested in demonstrating the broad applications of the method and working with archaeological materials can be fruitful in this respect. However, archaeological research may constitute a side or low-priority project for the analytical chemists involved, which limits the amount of time that they are willing or able to commit. For this reason, it is advisable to have individuals on the archaeological research team that have had or will receive training in ORA analytical techniques and data analysis.

How do conservation processes interfere with ORA?

(Grieve) While conservators try to minimize the negative effects of cleaning processes and chemicals on archaeological materials, it can sometimes be necessary to restore artifacts for interpretation. Historically, these included acid baths to remove encrustations and irreversible adhesives to ensure strong joins. Some excavation sites include conservators on their teams and decisions about how treatments will interact with future analysis can be discussed on site. In cases where ORA has not been identified as a priority, the restoration may have already been completed (such as with artifacts on display in museums). While we are still trying to understand the impact of conservation materials and techniques on analytical processes, conservators should clearly document all of the chemicals and materials that are being used so that these can be tested in conjunction with organic residues for identification purposes.

What should analytical chemists appreciate most about the archaeological environment?

(Mazow) Archaeologists are used to working in unpredictable environments that seem the antithesis of the analytical chemists controlled laboratory. The flexibility that fieldwork requires adds another level of complication to the already large communication gap between the disciplines. Terms like “sample,” “(non-) destructive” and even “clean” all have different meanings in these diverse settings.

Furthermore, the unknown and uncontrollable work environments that the archaeologist encounters when collecting potential residues multiply the contamination factors already introduced by the hundreds, if not thousands, of years since the sampled artifact was last in use—which is usually the object of the archaeologist’s research. Fortunately ORA is just one potential source of data that the archaeologist gathers when making an interpretation. It is usually as a result of questions raised by the archaeological context that the possibility of ORA data is even raised. ORA results, like artifacts or texts, do not stand as facts on their own but must be interpreted. A positive ORA result could be the smoking gun, but it is just one piece of evidence and must be placed within its archaeological context for it to have interpretive value. It may be because of this holistic approach that the degree of precision typically required in analytical chemistry is less decisive in archaeological inquiries. This is not to say that a high degree of precision is not beneficial, but in a highly degraded, highly contaminated ancient residue, it is also not expected. Nor is it the only piece of evidence on which the archaeological study is relying.

On Saturday, November 23rd at 8:20am during the 2013 ASOR annual meeting, an organic residue analysis workshop will be presented that will feature speakers who utilize ORA processes in their research. Dr. Zuzana Chovanec and Dr. Laura Mazow will review the variety of ORA techniques that are applied to archaeological materials with reference to a specific case study. Dr. Brendan Foley will discuss his work with DNA analysis on amphora from a marine environment. Dr. Eleanora Reber will describe the nature of ORA as it pertains to an understanding of the burial environment and excavation and promote the value of context and chemistry. Dr. Laura Mazow will demonstrate the relationships between archaeologists and analytical scientists utilizing a case study of ancient ‘bathtubs’ and Diane Allen will provide information on InfraRed and Raman spectroscopy technologies from an instrument representative’s perspective.

In conjunction with the workshop, several outreach platforms has been established to encourage discussion and promote ORA related topics:

Blog: http://organicresidueanalysis.wordpress.com

Twitter: #archORA

If you are a researcher who uses organic residue analysis in your project, we want to hear from you! Come to the 2013 ASOR workshop or reach out through the blog site!

Author Bios:

Zuzana Chovanec recently received her doctorate in Anthropology from the University at Albany. Her research centers on prehistoric Cyprus, Gas Chromatography/Mass Spectrometry (GC/MS), and the use of psychoactive substances, perfumes, and medicines in the Mediterranean.

Susanne Grieve is the Director of Conservation at East Carolina University in the Department of History. She has a masters degree in conservation from the University College London and is an objects conservator who has worked in Cyprus, Israel, Haiti, Peru, South Africa, Namibia and Antarctica on the preservation of historical and archaeological materials.

Laura Mazow is an Assistant Professor in the Department of Anthropology at East Carolina University. Her research interests are investigating the function of Bronze and Iron Age bathtub installations, and reconstructing ancient textile technologies and related cross-craft interactions.

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