Tracing the lead source of maiolica: a pilot isotopic study on artefacts from the area of Florence, Italy (fifteenth–nineteenth century)

Abstract The manufacturing of Italian maiolica (tin-glazed pottery) was extremely appreciated during the Middle Ages and Renaissance, leading to the production and collection of a rich cultural heritage. This pilot study aims to characterize the production technique and the origin of the lead used as a flux in a set of samples of maiolica glazes made in the area of Florence over a wide time span, ranging from the fifteenth to the nineteenth century. In particular, this is the first study that applies provenance analysis, using lead isotopes, to tin-glazed artefacts made in the site of Montelupo Fiorentino and by the Ginori manufactory in Doccia (Florence, Italy), both important production centres of ceramics in Italy. The samples were first analysed by scanning electron microscopy to characterize their layer structure and chemical composition. Lead isotope analysis was then performed by thermal ionization mass spectrometry and showed that the samples tend to be distributed into distinct groups according to their period of production. Moreover, the comparison with the lead isotope composition of the deposits of the European and circum-Mediterranean area from which lead was historically extracted showed that the isotopic composition of the samples differs from that of the Italian deposits, suggesting that lead was imported from abroad. The isotopic composition of all the investigated maiolica glazes is compatible with German ore deposits, in agreement with what is reported by the historical sources relating to the lead supply areas.