34 CONTEXT 181 : SEPTEMBER 2024 a complex mix of chemicals contributing to the preservative properties of tar. Creosote has been distilled as a separate timber treatment since the 1830s. References to tar and pitch rarely specify whether they derive from wood or coal. Those dated before around 1800 will relate to the former, and typically be made from Scots pine (Pinus sylvestris) due to its widespread distribution and high resin content, which resulted in a superior-quality tar. Pine tar is most commonly known as Stockholm or Archangel tar but many other names can be used to denote its origin. Following the introduction of coal tar in the late 18th century, it is frequently distinguished as common, vegetable or foreign tar. As these names suggest, wood tar was an imported product largely supplied by Scandinavia and the Baltic, with Sweden holding a monopoly in the early modern period (c1500–1800). These regions have a long tradition of making tar, whereas England lacked the necessary raw material to develop an industry.² The only native Scots pine in the British Isles is found in the Scottish Highlands, but its quality was perceived as poor and there is little indication of tar production.3 The architectural use of wood tar is well known in Nordic countries, with the medieval stave churches of Norway and Sweden representing some of the best examples of the tradition. In England, however, wood tar is principally recognised for its role in the building and maintenance of ships, with little attention paid to its architectural use. While the early history is vague, it is likely that the adoption of tar as a building material derived from the Nordic tradition, possibly in response to the introduction of pre-cut timber in the early medieval period. The overseas timber trade, well documented in medieval customs accounts, largely took the form of thin softwood boards used for weatherboarding, eaves boards, floorboards, guttering and doors.⁴ Unlike hardwood, which needs no treatment in most situations, external softwood requires a protective coating like tar, limewash or linseed-oil paint. However, tarred oak examples are known from southern Norway, such as Høyjord Stave Church, suggesting that tarring could also be a decorative custom.⁵ Medieval building accounts provide the earliest known documentary evidence for the architectural use of tar in England and reveal some unexpected applications. Pitch is Urnes Stave Church (Photo: Bjørn Erik Pedersen, Wikimedia) ² Hennius 2018 3 Smout, MacDonald and Watson 2004 4 Schofield 1991 5 Thun et al 2016
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