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Tin-based opacifiers (lead stannate yellow and tin oxide white) were first used in glass production for a short period in Europe from the second to the first centuries BC , and then again throughout the Roman and Byzantine Empires from the fourth century AD onwards. Tin oxide was also used in the production of Islamic opaque glazes from the ninth century AD , and subsequently in enamels applied to Islamic and Venetian glasses from the 12th century AD onwards. A selection of published analytical data for the tin-opacified glasses, enamels and glazes is summarized, and the methods used in their production are reassessed. The phase transformations occurring when mixtures of lead oxide, tin oxide and silica are fired are investigated with high temperature X-ray diffraction (XRD) using a synchrotron radiation source, and these results are used to explain the observed differences in the glass, enamel and glaze compositions. Possible reasons for the use of tin-based opacifiers in the second to first centuries BC , and for the switch from antimony-to tin-based opacifiers in the fourth century AD are suggested, and the possible contexts in which tin-based opacifiers might have been discovered are considered. The introduction of tin-opacified glazes by Islamic potters in the ninth century AD is discussed in terms of technological transfer or independent invention.

The origin of the colorants in Egyptian glass of the second millennium BC has been the subject of much research and debate. Several colorants including lead antimonate yellow and calcium antimonate white appear in the archaeological record apparently concurrently with the introduction of glass, and it is possible that their origins are in some way linked. This paper examines the use of the antimonate colorants and uses analytical and experimental techniques to deduce possible technologies of production. Trace element data derived from a pilot study by LA-ICPMS gives additional indications of a possible source in the Caucasus for the antimony of these glasses.

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A recent analytical study by SEM–WDS was carried out on 226 glasses from the Late Bronze Age, analysing each of the glasses for a total of at least 22 elements, the largest such analytical study conducted on these glasses. The aim of the analysis was first to identify which elements were brought in with each of the raw materials and, second, to accurately characterize those raw materials. Since different glassmaking sites in Egypt and the Near East would probably use at least some local raw materials and these raw materials will vary slightly from site to site, this has potential for provenancing the glass. Analysis showed new patterns in the compositions of glass from the various sites and led to new conclusions about the supply of raw materials and personnel for the glass workshops. This forms the basis for further work by LA–ICPMS to be presented in part 2 of this paper.

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