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An 11th century Byzantine church in central Turkey, excavated by Robert Ousterhout (School of Architecture, University of Illinois), was constructed in three distinct phases and decorated with fresco painting in four different interior spaces: 1) the naos, 2) the south narthex and the north narthex, and 3) the parekklesion. Selected red, blue and green pigments were analyzed to determine whether differences in composition might support the proposed architectural chronology of the building.
Although SEM/EDS and some XRD of these 12 pigments was performed in 1996, Pankaj Sarin (Materials Science and Engineering) redid the EDS experiments and completed the XRD, confirming the presence of distinct mineral compounds for red, blue, and green pigments in different parts of the building. For example the relatively rare ultramarine violet (Na5HAl4Si6S4O24.H2O) appears in the north narthex only. In addition, the composition of the underlying plaster appears to change over time from calcite (CaCO3) to gypsum (CaSO4.2H2O), either as a result of a deliberate change in plaster recipes or accidental exposure of some frescoes to sulphur dioxide in the atmosphere.
These results suggest the frescoes in four parts of the building were painted at different times using different pigments.
Papers on this project were presented at the 1996 International Symposium on Archaeometry (ISA) in Urbana, Illinois, and at the 1998 ISA in Budapest, Hungary. The Budapest paper, entitled "Fresco Pigments from Byzantine Cappadocia, Part II," (authors Sarah Wisseman (ATAM), Pankaj Sarin, Robert Ousterhout, Eric De Sena (ATAM and Art History), and Wendell Williams (Physics, Emeritus) was published in BAR/Archeaeolingua Central European Series 1 Archaeometry 98. Proceedings of the 31st International Symposium on Archaeometry, Budapest, April 26-May 3 1998, vol. 1, pp. 1-4. Erzsebet Jerem and Katalin T. Biro, eds. Archaeopress, Oxford. For further information, consult the British Archaeological Reports website.
Copyright 1999. University of Illinois at Urbana-Champaign.
