Lead provenance for medieval decorated tile glazes from Brittany and Anjou (13th-14th c.)

Medieval pavements composed of lead-glazed tiles decorated with a variety of techniques continue to inspire questions about the organisation of glaze manufacture, and the supply and origin of lead materials. The tiles analysed in this study are from Suscinio I (a 13th-century pavement) and Suscinio II (a 14th-century pavement), at the Cha9teau of Suscinio in Brittany, and also from the 14th-century pavement at the fortified manor house in Brain-sur-Allonnes, Anjou. Lead isotope analysis (LIA) was used to examine samples from 44 lead-glazed tiles, 29 of which are transparent, while 15 are tin-opacified (an exogenous technique in these regions during this period). Five out of the six LIA groups thus identified favour site-specific supply networks, while results for the remaining group, LIA5, indicate a multi-site supply network. After combining LIA results with archaeological and historical data, the most likely provenance for the lead materials in LIA5 is Derbyshire, in the British Isles. Both the importation of ready-to-use glazing mixtures and the use of lead from neighbouring mines can now therefore be discounted as plausible hypotheses for the production of the tin-opacified lead-glaze tiles analysed in this study.