Two unique Byzantine immured lead-glazed relief ceramic icons and related tiles from the church of St Basil in Arta,Greece: investigation and interpretation of materials and techniques

St Basil’s late Byzantine church in Arta (NW Greece) is unique among other surviving churches of the same era as a result of two glazed relief ceramic icons and arrays of square glazed tiles that decorate its external wall. The latter decorative items were carefully examined by means of analytical techniques in order to reveal the materials and techniques used for their manufacture and thus interpret their connection to the contemporary Byzantine and Italian ceramics. Analytical results indicate that lead plus quartz suspensions were employed for the fabrication of the majority of the glazes in the spirit of recipes for Italian Archaic majolica pottery, and thus they are differentiated from the common contemporary Byzantine products. Nonetheless, the raw materials used in the Arta area ceramics deviate substantially from those used in the Italian products and, possibly, a local (NW Greece) production is reflected. The unexpected rather rich variety of raw materials and/or techniques that underlies the visual uniformity of the glazed material in consideration might reflect selection of the best products generated upon experimentation with various contemporary technical alternatives. Finally, the decorative arrangement of the glazed items that we see today might reflect a way to circumventing original objections to the ceramic icon innovation.