Art and Cultural Heritage: Discoveries during the Pandemic Year: Session II
Sponsored by: ACerS Art, Archaeology, and Conservation Science Division
Program Organizers: Marie Jackson, University of Utah; Jamie Weaver, National Institute of Standards and Technology

Wednesday 2:00 PM
October 12, 2022
Room: 402
Location: David L. Lawrence Convention Center

Session Chair: Jamie Weaver, National Institute of Standards and Technology; Marie Jackson, University of Utah


2:00 PM Division Meeting

2:20 PM  Invited
From the Study of Ancient Objects to the Scientific Study of Culturally Innovated and Curated Technologies: Pamela Vandiver1; 1University of Arizona
    From inception of ACerS in 1898, members published technological studies of historic pottery, porcelain, glass and building materials. Following World War II, study of ancient materials expanded beyond optical microscopy, composition and replication to development and application of analytical techniques that determined microstructure, properties and performance. A meeting at The Center for Advanced Studies, Princeton, organized by Agora archaeologist Homer Thompson, asked how science could contribute to archaeology. Willard Libby, Anna Shepard and others contributed by developing analytical techniques and research strategies that revolutionized study of ancient objects in museums and from archaeological sites and that led to conservation studies. For the international year of glass in 1968, the British Museum mounted a major exhibit of the history of glass technology that led to a focus on what we did not know. In 1970s and 80s, interdisciplinary studies coalesced into field of archaeological science with expanded research questions, techniques, results.

3:00 PM  
Reproduction of Melting Behavior for Vitrified Hillforts Based on Amphibolite, Granite, and Basalt Lithologies: John McCloy1; José Marcial2; Jack Clarke3; Mostafa Ahmadzadeh1; John Wolff1; Edward Vicenzi4; David Bollinger1; Erik Ogenhall5; Mia Englund5; Rolf Sjöblom6; Albert Kruger7; 1Washington State University; 2Pacific Northwest National Laboratory; 3University of Sheffield; 4Museum Conservation Institute, Smithsonian Institution; 5The Archaeologists, National Historical Museums (SHM); 6Luleĺ University of Technology; 7US Department of Energy
    European Bronze and Iron Age vitrified hillforts have been known since the 1700s, but archaeological interpretations are still debated. We carried out experiments to constrain conditions leading to vitrification of wall rocks in the hillfort at Broborg, Sweden. Potential source rocks were collected locally and heat treated in the laboratory, varying maximum temperature, cooling rate, and particle size. Crystalline and amorphous phases were quantified using X-ray diffraction in situ, during heating and cooling, and ex situ, after heating and quenching. Textures, phases, and glass compositions were compared with samples from the vitrified wall and equilibrium crystallization calculations. ‘Dark glass’ formed from amphibolite rocks melted at 1000-1200°C under reducing atmosphere then slow cooled. ‘Clear glass’ formed from non-equilibrium partial melting of feldspar in granitoid rocks. This study aids archaeological forensic investigation of vitrified hillforts and interpretation of source rock material by mapping mineralogical changes and glass production under various heating conditions.

3:20 PM  
The Identification of Materials and Processes Used in the Manufacture of Orotone, Hand-Colored Orotone, and Silvertone Photographs: Vanessa Johnson1; Ivanny Jácome-Valladares1; Claire Kenny2; Tami Lasseter Clare1; 1Portland State University; 2University of Washington
     The orotone photographic process utilizes a positive image on a clear glass plate with a gold-colored metallic backing. This study analyzed seventeen orotones and silvertones to determine materials used in their production. X-ray Fluorescence (XRF) spectroscopy identified copper and zinc in all metallic backings, while XRF and with Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS) identified aluminum in a silvertone backing. XRF spectroscopy identified silver bromide as the imaging material in all photographs. Glass for all orotones was determined to be soda-lime silica glass and sometimes contained arsenic or lead additives. XRF, Raman and Fourier Transform Infrared (FTIR) spectroscopies found vermilion, chromium yellow, cadmium yellow, and Prussian blue pigments in hand-colored orotones.Analysis of a delaminating orotone using Pyrolysis/Gas Chromatography/Mass Spectrometry (Py/GC/MS) identified methacrylate polymers in the backing fluid. Ultraviolet-induced aging tests of amyl acetate, the most common backing fluid in orotones, ruled out these two acrylates as aging products.

3:40 PM Concluding Comments