Science Notes – Early medieval insights from birch bark tar

Ceramic vessel 1112 from Ringlemere; the interior was coated in a black residue that contained birch bark tar. [Image: © Trustees of the British Museum]

Birch bark tar (manufactured by the heating of bark in airtight conditions) has long been prized for its sticky, water resistant, and biocidal properties. Throughout human history it has seen a wide range of uses, including as a sealant (for example, in waterprooing vessels), an adhesive (for hafting weapons, repairing ceramics, or assembling composite objects like jewellery), and in perfume and medicine.

Archaeological evidence demonstrates that our predecessors were making this substance as far back as the Palaeolithic (the earliest discovery dates back c.185,000-135,000 years), and its use has continued into the modern day in eastern and northern Europe. In western Europe and Britain, though, it has been generally believed that its use was limited to prehistory, with birch bark tar being displaced by pine tars during the Roman period. As we will explore during this month’s Science Notes, though, the identification of birch bark tar at two early medieval sites in the east of England indicates that this technology was in use much later here than was previously believed.

Read the rest of this article...