New evidence of re-use of an oak panel in Estonia: Covers of the fifteenth century Codex of Türi

Abstract

In 2021 the Codex of Türi, dating from 1454, came into the hands of conservators. The manuscript, bound in Gothic style, with oak boards covered in leather, was in poor condition. The leather covering the boards and the text block were partially detached, the binding was loose, and the thread was broken. In the first stage of conservation, the leather was removed from the covers. The exposed oak boards allowed for dendrochronological analysis to determine the age of the wood used for the covers. Additionally, ⁸⁷Sr/⁸⁶Sr isotope analysis was conducted to assess the origin of the cover wood.

The dendrochronological study showed that the wood used for the covers was from trees felled in the same late medieval period as the Codex was written. While the felling of the tree for the back cover dated to around the year of the completion of writing the codex, the outermost preserved tree ring of the front cover was 88 years older, but no sapwood was preserved on this. A non-functional round hole, repaired with a wooden plug, was observed in the front cover. The hole is a remnant of the earlier usage of the board before it was adjusted to the cover of the manuscript. This suggests that the front cover was used for a different purpose previously.

The dendrochronological dating indicated different origins for the cover boards. The ring series of the front cover are similar to oak chronologies from north-central Poland, while the back-cover oak has most probably grown somewhere in western Latvia/Lithuania.

The dendrochronological study was compared with strontium isotope analysis of the boards. Strontium isotope analysis interpreted using a modelling approach supports the likelihood that the wood of the front cover grew in the region around the Lower Vistula River and the back cover grew in western Latvia/Lithuania. Detailed baseline maps for these regions are missing but this study on few items has nevertheless yielded very interesting results.