Dendrochronological dating of wooden artifacts by measuring the tree rings using magnifying glass and photography-assisted method: an example of a Dutch panel painting

摘要

Dendrochronology, an analysis of tree rings, is a commonly used method for dating wooden structures in archaeological remains and historical objects. Fascinating subjects of examination are the historical oil paintings on oak panels. Here, we applied a tree ring analysis on three boards of a Dutch painting from the Sinebrychoff Art Museum (Helsinki). Tree rings were measured using the conventional lens-assisted method, in addition to the photography-based approach, where the widths of the rings were determined from digital enlargements of the photos. These two methods produced comparable tree ring series. The lens- and photography-based records of the measured panel exhibited higher agreement with each other than the conventional, lens-based, record against the different master chronologies. Dendrochronological cross-dating against the master chronology showed that the rings of the panel represent the period ad 1413-1620. Cross-dating was attained by comparing the tree ring series of the panel painting with the previously published chronologies obtained from timber transported from the historical ports of the Eastern Baltic Sea to Western Europe. Photography appears as a promising method to be used for dendrochronological investigations of archaeological and historical objects, alongside the conventional methods. We note that the importance of using photographs of tree ring cross sections was highlighted already in the 1930s. In the digital era, the photographic approach shows obvious benefits for archival purposes and remeasuring the rings, with additional future prospects of image processing and analyses.