pitch and tar
a multi-disciplinary study of sources, technology and preservation
- Nigel Nayling, University of Wales Trinity Saint David
- Toby Jones, Newport Museum, Newport City Council
- Keith Smith, Cardiff University
- Anette Hjelm Petersen, Roskilde - The National Museum, Denmark
- Marie Curie Intra-European Fellowship
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Tars and pitches are black sticky substances obtained by the destructive distillation either of wood, bark, or tapped resin from soft and hardwood trees such as pine, spruce and birch. They have widely been used in the past as waterproofing agents and timber preservatives, especially in maritime contexts. In the medieval period, their role in shipbuilding and maintenance led them to acquire crucial strategic and political importance for the developing European seafaring economies and naval fleets.
Material from the recently excavated Newport Ship discovered in 2002 on the right bank of the river Usk in Newport, Wales is central to this study. The wreck is the most complete example of a fifteenth century clinker-built vessel ever found in the UK. The dating evidence indicates that it was constructed after AD 1445 and came to rest in Newport soon after AD 1468, while associated finds suggest contacts with the Iberian peninsula. This unique assemblage supported by the analysis of comparative material, offers scope for the investigation of ship building techniques and maintenance strategies alongside examination of differential preservation due to burial environment.
Analytical chemistry techniques and experimental modelling will be used to assess the production technology, botanical and geographical origin of the Newport Ship waterproofing materials and preservatives. A systematic study to map the use of tars and pitches over the whole vessel will lead to understand the construction and later repair of the ship and will also offer us the chance to examine the economics behind the use of these substances in the shipyards of medieval Europe.
Interpretation of the Newport material will be supported by the analysis of comparative material from further archaeological sites (Sutton Hoo ship burial, England; The Roskilde wrecks, Denmark; Grace Dieu, England; St Peter Port wrecks, Guernsey; Doel cog, Belgium) with differing preservation conditions enabling the impact of both intra- and inter-site variability in burial environment to be compared.
Tars and pitches from the collection of the British Museum will also be incorporated into this study to widen the range of depositional environments further, to permit examination of the influence of the museum environment on the long-term stability of these materials and to develop best practices for the curation and conservation of these materials in museum collections.
Interpretation of the archaeological data will be supported by analysis of experimentally produced and artificially aged material.
In the media
Ship researchers get stuck into tar and pitch, Western Mail, 8 October 2010