Congratulations to Brittany Dolph and Alexis North who were each awarded an FAIC George Stout grant to help support their attendance at conferences this spring, where they each will be presenting.
Brittany will present at this year’s Society for American Archaeology annual meeting in Honolulu, HI, April 3-8. Her paper, “Sandstone raw materials from Eastern France: Evaluation of non-invasive portable technologies as potential tools for characterization and sourcing”, is based on research she conducted with UCLA/Getty faculty Dr. Christian Fischer as part of the class “Portable Technology for Materials Analysis”. Her paper will be presented in the session “Archaeometric Methods, Archaeological Materials and Ancient Technologies” organized by UCLA/Getty Program chair Dr. Ioanna Kakoulli and staff member Vanessa Muros, and sponsored by the Society for Archaeological Sciences.
Alexis will be presenting at this year’s AIC Annual Meeting in Indianapolis, IN, May 29-June 1st in the Objects Specialty Group session. Her paper, “Beyond the Visible: Macro and Micro Analytical Forensic Imaging for the Documentation and Investigation of Archaeological Objects” is a continuation of work she began back in the fall of 2012 when she tested the use of a tunable forensic light source to image the polychrome decoration on a pre-Columbian vessel she was treating. Since then, Alexis has been working with UCLA/Getty Program chair Dr. Ioanna Kakoulli to investigate applications of this technique taken from the field of forensics to the examination and documentation of archaeological objects.
Congratulations again to them both and we wish them luck with their presentations!
Sandstone raw materials from Eastern France: Evaluation of non-invasive portable technologies as potential tools for characterization and sourcing
Brittany Dolph and Christian Fischer
In the Alsace region of eastern France, sandstone is an important local resource which has been utilized by societies throughout time. Although earliest archaeological evidence of usage dates back to the Neolithic, it is mainly during the Gallo-Roman and Medieval periods that this sandstone was extensively quarried, and nowadays is still commercially exploited for building and conservation purposes. Primarily composed of quartz, feldspars, and various types and amounts of micas and clay minerals, the sandstone types present variegated colors and belong to different levels of the Buntsandstein, a lithostratigraphic unit of lower Triassic age. This research explores the potential of X-ray fluorescence (XRF) and ultraviolet/visible/near infrared (UV/Vis/NIR) spectroscopy for the non-invasive characterization of different Buntsandstein sandstone lithotypes using portable instrumentation. The two complementary non-invasive techniques allow identification of both elemental and mineralogical compositions while providing a useful alternative for the analysis of archaeological artifacts and/or field investigations where sampling is not an option. Furthermore, they can be used to document current condition and possible alteration processes in order to identify decision-making criteria for conservation treatments. Preliminary results obtained on reference samples from modern quarries exploiting the Buntsandtein sandstone will be presented and discussed with particular focus on provenance and sourcing.
Beyond the Visible: Macro and Micro Analytical Forensic Imaging for the Documentation and Investigation of Archaeological Objects
Alexis North and Ioanna Kakoulli
Digital analytical imaging utilizing the properties of visible (Vis), ultraviolet (UV), and infrared (IR) light has become a standard documentation and diagnostic tool used by conservators and art historians not only to create a record of an object’s appearance and condition, but also to uncover its method of manufacture, history, and previous conservation treatment. This non-invasive method has enabled the examination of a variety of objects of different geometry, complexity, and value providing useful information not discernible with the naked eye. Recent advancements in the medical and forensic imaging fields have led to the introduction in conservation of improved methods in the examination and documentation of objects of archaeological, historical, and artistic value.
This paper discusses the application of a forensic alternate light source (ALS) with tunable light capabilities for the analysis of objects under specific wavelengths of light and illumination conditions. Combining the tunability of the light source with longpass, shortpass, and bandwidth filters positioned in front of a modified DSLR camera in which the UV/IR blocking filter has been removed, an object is analyzed using reflectance and fluorescence imaging at the spectral range between 350 nm (ultraviolet-UV) and 1000 nm (near infrared-NIR). From the monochromatic images captured, false-color reconstructed trichromatic images including UV and IR false-color images can be obtained, enhancing specific features not easily discernible in the original black and white images, and assisting in the qualitative identification of certain materials.
The results obtained from this versatile approach show that augmenting analytical imaging with forensic technologies is an invaluable first step in the
examination of objects, being an excellent tool for screening and preliminary characterization of materials. For example, reflectance in the UV and
luminescence in the visible and NIR were performed on an ancient ceramic with a highly obscured surface, revealing long-lost decoration not visible in
standard UV-induced visible fluorescence or NIR reflectance imaging. Issues of authenticity in a law enforcement setting were also resolved with the discovery and identification of traces of ancient paints based on their specific visible and infrared fluorescence emissions.