A 17th century bell foundry in the belfry (UNESCO’s world Heritage site) of Gembloux (Belgium): an archaeometric study

This study presents the first comprehensive analysis of a late 17th-century bell foundry workshop excavated within the UNESCO-listed belfry of Saint-Sauveur church in Gembloux (Belgium). Archaeological investigations revealed exceptionally well-preserved structures, including a casting pit, the kiln floor of a smelting furnace, and ash pits, alongside a significant assemblage of artifacts: 29,000 clay mold fragments (core, false-bell and cope moulds), bricks, crucibles, slag, and copper alloy residues. Archaeomagnetic dating places the foundry’s activity between 1669 and 1689 CE, likely following a devastating fire in 1678. At this time, the bell founders from eastern France established temporary workshops near the bell installation sites. Thin-section petrography and EDS (Energy-dispersive X-ray spectroscopy) analyses identified local loess as the primary raw material for moulds and bricks, with lime and sand as well as vegetal, and animal fibres added to the clay moulds for structural enhancement. Preliminary botanical analysis suggests the use of flax, hemp, or nettle fibres in the moulds. Crucibles, however, were crafted from refractory clays imported from the Meuse Valley, indicating external specialized production. This multidisciplinary research provides valuable insights into historical bell-making techniques, raw material sourcing, and the regional network of itinerant artisans, contributing to the conservation and cultural development of this unique heritage site.