Efficiency of using Calcium Oxalate for Protection of Monumental Limestone and Marble

I. MIHALIC; A. KARYDAS; S. FAZINIC; JUAN JOSÉ LEANI; D. MUDRONJA; A. MIGLIORI

Gotemburgo

Congreso; European Conference on X-Ray Spectrometry (EXRS); 2016

University of Gothenburg

The manufacture of Attic black gloss was introduced during the classical period in Athens by applying a complex three stages oxidation-reduction-oxidation firing process of illitic clay enriched in iron [1]. Through the time, the black gloss manufacture technology was transferred to workshops operating in Sicily and Southern Italy. In many cases the quality of the black gloss in Italian imitations is so high that it is difficult to discriminate these artworks from the original Attic pottery.In this work, we have developed a new experimental methodology for the analytical study of the Attic black gloss decorative layer using tunable synchrotron radiation at grazing incidence excitation conditions [2]. In this way, the X-ray fluorescence (XRF) radiation is emitted only from the black gloss surface layer of a few tens of micrometers. This methodology was applied and validated at a joint experimental facility of the International Atomic Energy Agency and Elettra Sincrotrone Trieste operated at the XRF beamline. Several original black gloss and imitation pottery fragments manufactured in Sicily and South Italy with well-documented archaeological reference were examined by means of XRF analysis at three different excitation energies and X-ray absorption near-edge structure spectroscopy across the Fe K-edge.The quantitative results obtained for the trace elements content and the formal oxidation state of Fe provided new insights on the provenance and manufacturing technology of the black gloss pottery across the Mediterranean area during the classical period.