There are two things you should know up front before you read this post. 1) This talk was fascinating. 2) I am not going to do it justice. I couldn’t take notes quickly enough and it didn’t help that I was frequently mesmerized by the beautifully colored images.
This paper briefly reviewed current methods for digital analytical imaging using visible, ultraviolet, and infrared light, but its true focus was on exploring and adapting technology from crime scene investigation for use in object examination. Specifically, the authors looked at the use of an alternative light source (ALS) combined with a different filters on a modified digital single-lens reflex camera (DSLR – modified by removing the UV/IR blocking filters). The ALS allows the user to choose specific wavelengths of light for illumination and, by using filters on the DSLR, reflectance/fluorescence can then be captured between 350nm and 1000nm. In this case, a Mini-CrimeScope 400 ALS was used along with a modified Nikon D90.
Multiple projects were featured to show the capabilities and limitations of the technique, all focusing on the investigation of archaeological ceramics. The authors began by creating reference panels of expected ancient pigments and binders, as well as of potential modern materials including adhesives. They then experimented to find successful combinations of excitation and emission. For one of the projects used as an example, an ancient Greek incense burner with a figure of Nike, this method of investigation was able to identify Egyptian blue and madder lake pigments. In this example, illumination was in the green spectrum and capture was in the red and vice-versa (if I’m remembering correctly). On a Roman figurine, the technique identified madder lake, but also pointed to the need for further testing of a green pigment which did not fluoresce (it turned out to be green earth). Additional examples included a Pre-Columbian ceramic and two Italian ceramics.
In summary, this paper demonstrated that forensic photography with a broadband light source can successfully be used for qualitative identification of a variety of ancient and modern materials. What’s exciting about this (at least for me) is its potential application to archaeological field settings. After all, crime scene investigation happens entirely “in the field” and this technique is completely portable. It also promises to be relatively simple once successful combinations are worked out for different materials. The ALS price tag is not exactly cheap, and the cost is likely to vary a bit depending on who’s buying (police department, university, etc.), but at roughly 15K it is in a more affordable category than, say, portable X-ray fluorescence. Plus, you end up with visually appealing and instructive images, which would frankly be great in both scholarly publications and museum didactics.
This paper also highlighted (for me) the debt we owe to graduate students like Alexis North (currently at the UCLA/Getty Program in the Conservation of Archaeological and Ethnographic Materials) and faculty like Ioanna Kakoulli (also at UCLA in the Materials Science and Engineering Department and Chair of the Conservation Program). Where would we be without graduate student research? Many of my archaeology colleagues will be delighted to know about this non-destructive possibility for investigating objects in the museum and in the field.
41st Annual Meeting – Objects Session, May 31, "Beyond the Visible: Macro and Micro Analytical Forensic Imaging for the Documentation and Investigation of Archaeological Objects,” by Alexis North and Dr. Ioanna Kakoulli
