The Late Antique glass furnaces in the Hambach Forest were working glass - not making it

The cluster of Late Antique glass furnaces in the Hambach Forest in the Rhineland, western Germany, has been advocated by K.H. Wedepohl and G. Hartmann in their influential papers as a potential location for primary glassmaking. Here, we re-evaluate and expand the original chemical data and assumptions underpinning this controversial interpretation, and present an alternative explanation for the compositional pattern observed among the glass finds from the site and its wider environment. Glass matching very closely the two main chemical compositions as seen in the Rhineland has recently been reported from numerous 4th to 5th century CE sites in Southern France, Britain, Italy, the Balkans and Egypt, with the same pattern of minor amounts of colorant elements such as copper, tin, lead and antimony, as contamination due to the inclusion of recycled cullet into the batch. The high content in iron and related elements, previously seen as a unique characteristic of the Hambach Forest glass finds, is now recognised as a common feature of these established super-regional compositional glass groups. We identify the majority of analysed finds to consist of HIMT glass, followed by a significant number of serie 3.2 glass sensu Foy et al. (2003), while only one sample matches glass of the Levantine composition. This sees the furnaces of the Hambach Forest, and the finished vessels excavated in the wider region, fully integrated in the two-tier Late Antique glass industry, where a few eastern Mediterranean megaproducers were supplying their raw glass across the Empire to be re-melted and worked locally into artefacts, including at the cluster of glass furnaces in the Hambach Forest.