Swedish oak, planks and panels: dendroarchaeological investigations on the 16th century Evangelistas altarpiece at Seville Cathedral (Spain)

Five panels were selected for this research. The observed technological features allowed the reconstruction of the production process from borne (oak wainscots) to the final product and, based on that, two types of panels were described. Dendrochronological results showed that the wood employed in both types of panels represents a rather homogeneous group, implying that the raw material was probably transported to Seville in the same batch, and was prepared and assembled using slightly different methods to meet the requirements stipulated by the contract. Sapwood was identified in 12 of the 33 researched planks. The most recent tree-ring dates in AD 1549. Using a Bayesian approach, we obtained the combined felling date range AD 1549 to 1554 for six of the trees with a 99.7% confidence level. This would allow for a seasoning time of a couple of weeks up to four years, although we cannot discard that some of the other trees were cut earlier and had longer seasoning periods. Interestingly, our research provides evidence that the wood originated from the southwest of Sweden, representing an alternative source to the south-eastern Baltic oak commonly used for panel paintings in northern Europe in the 16th century. This is the first time that such procurement source is reported by dendrochronology in an altarpiece. Wood technological features of the planks and panels are compared to those of Baltic oak wainscots and to contemporary altarpieces in Spain and Portugal. Possible reasons for the use of this alternative procurement source are discussed.