Mechanical strength of wood from the Vasa shipwreck

IRG/WP 08-20381

A O Rapp, C Brischke, C R Welzbacher, T Nilsson, C Björdal

Samples from three ancient ship wrecks (Vasa, Elefanten, and Gröne Jägaren) and recent oak samples as reference were examined with regard to mechanical strength using the high-energy multiple impact (HEMI) - test method, which delivers the resistance to impact milling (RIM) of a material. Adoption and optimisation of the test method for the particular sample size of the wooden drilling cores was necessary. After that optimisation the HEMI method proved to be suitable not only for cube like specimen but also for specimens from wooden drilling cores. The RIM of the different wreck samples was partly significantly different from the recent reference material. Low values indicated deterioration of some cores. Interestingly the wooden core with high iron content showed the highest RIM, even significantly higher than that of untreated recent oak.

Keywords: high-energy multiple impact (HEMI) - test ; strength loss, water logged wood, cultural heritage, wood conservation, PEG, iron, sulphur, pH

Conference: 08-05-25/29, Istanbul, Turkey

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