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Home » News » Andrea Ceglia defended his PhD thesis on 1 July 2015 and was awarded the degree of doctor in engineering

Andrea Ceglia defended his PhD thesis on 1 July 2015 and was awarded the degree of doctor in engineering

July 10, 2015 at 14:02

The aim of his doctoral work was two fold: on one hand he aimed at assessing the feasibility of optical absorption spectroscopy to study ancient glass materials; on the other hand he wanted to contribute to the current archaeological understanding on technological and socio-economic aspects of glass organisation of the production, trade and distribution. In particular he focussed on unravelling the technological know-how of Roman glassmakers to produce black appearing glass and on characterising the distribution patterns of raw glass in Cyprus during Late Antiquity (4th-7th century AD).He paid particular attention to the study of iron because this element was the main colourant of ancient glasses. Most of the time it was added as impurity of the sand, while in the case of certain black glasses it was deliberately added. To assess the feasibility, strengths and weaknesses of optical spectroscopy in this field of study Andrea produced a series of iron doped soda-lime-silica glasses in collaboration with the AGC Glass Europe company to simulate the natural presence of iron in glass. These glasses were used to correlate the absorbance of glass to Fe2+ iron concentration. The calibration was compared against the determination obtained by synchrotron X-ray absorption spectroscopy.Furthermore, Andrea studied the material excavated from three ecclesiastical sites of Cyprus dated between the 4th and the 7th century: Ayioi Pente at Yeroskipou, Maroni Petrera and Kalavasos Kopetra. A large number of glass fragments were studied with in situ optical spectroscopy and a selection of them based was chemically analysed by means of Electron Micro Probe Analyser (EPMA) in order to define the optical parameters which would link the absorption spectra to specific glass compositions. In addition, this study allowed the identification of the glass types consumed on the island, and showed a geographical/chronological evolution. This work demonstrates that optical spectroscopy is a valid technique to determine the concentration of Fe2+ in ancient glass and to categorise the glass types of Late Antique glass.Moreover, he investigated the case of the deliberate addition of iron to produce black colour. Because of the high absorbance of these glasses, he employed synchrotron X-ray absorption spectroscopy. The study of black glass jewellery and vessels dated between the 1st and the 5th century AD shows that there is a technological change at the end of the 2nd century. Black glass was initially produced by controlling the redox conditions in the melting furnace, while in later times the colour was obtained by large additions of iron minerals with no particular attention to the redox conditions.

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