Birch-bark tar in the Roman world: the persistence of an ancient craft tradition?

Birch-bark tar, used continuously in the territory of modern Europe from the Middle Palaeolithic to the Iron Age, is conspicuous by its absence in the archaeological record of the Roman period, suggesting its replacement by conifer-based products. The results of chemical analyses of residues on Roman hinges, however, now challenge this interpretation. The presence of birch-bark tar in most of the samples demonstrates the persistence of a long-established practice into the Roman period. Examined in relation to textual and environmental evidence, these results illuminate the transmission of technical knowledge and the development of long-distance trade networks associated with birch-bark tar.