The Power of Pine Tar

Pine tar was critical to a Viking longship for waterproofing the hull, preserving the wood, and more. A single ship required hundreds of litres of tar depending on its size. A fleet required thousands. But where did it all come from?

In 2018, archaeologist Andreas Hennius of Uppsala University published a landmark study in the journal Antiquity that finally answered that question.

His answer: industrial-scale production sites hidden deep in the forests of Uppland, Sweden. Hennius documented large funnel-shaped pits, carbon-dated to 680–900 AD — the precise window of the Viking expansion. A single pit could produce up to 300 litres in one burn. And there may have been pits like these scattered across the northern world.

Read more in my essay about Viking ship economics.

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