X-ray computed tomography for non-invasive dendrochronology reveals a concealed double panelling on a painting from Rubens' studio.

Marta Domínguez-Delmás,Jan Dorscheid,K Joost Batenburg,Moorea Hall-Aquitania,Francien G Bossema,Sophia Bethany Coban,Erma Hermens

doi:10.1371/journal.pone.0255792

Abstract

Dating the wood from historical art objects is a crucial step to ascertain their production time, and support or refute attribution to an artist or a workshop. Dendrochronology is commonly used for this purpose but requires access to the tree-ring pattern in the wood, which can be hindered by preparatory layers, polychromy, wax, or integrated frames. Here we implemented non-invasive dendrochronology based on X-ray computed tomography (CT) to examine a painting on panel attributed to Rubens’ studio and its presumed dating around 1636 CE. The CT images achieved a resolution of 37.3 micron and revealed a double panelling, which was concealed by oak strips covering all four edges. The back (visible) board is made of deciduous oak (Quercus subg. Quercus), the most common type of wood used in 17th-century Netherlandish workshops, and was dated terminus post quem after 1557 CE. However, the front (original) board used for the painting has been identified through examination of the wood anatomy as a tropical wood, probably Swietenia sp., a species seldom used in Netherlandish paintings, and remains undated. Its very presence attests the global character of 17th-century trade, and demonstrates the use of exotic species in Flemish studios. The date of the oak board refutes previous results and suggests that this board was trimmed to meet the size of the tropical one, having been glued to it for conservation purposes or with deceiving intentions to pretend that the painting was made on an oak panel. These revelations have opened new lines of art historical inquiry and highlight the potential of X-ray CT as a powerful tool for non-invasive study of historical art objects to retrieve their full history.

Highlights

A wide array of sciences and techniques are presently available to investigate the production and state of conservation of paintings on panel (e.g. [1])
State-of-the-art X-ray computed tomography (CT) scanning has seldom been used on panel paintings for dendrochronological research
Two studies report on the potential of this technology to assess the manufacturing technique and preservation state of panel paintings [26, 63], whereas only [24] presents a successful dendrochronological study of two panel-doors from a shrine in Norway

Summary

Introduction

A wide array of sciences and techniques are presently available to investigate the production and state of conservation of paintings on panel (e.g. [1]). A wide array of sciences and techniques are presently available to investigate the production and state of conservation of paintings on panel Establishing the time and place of their production supports their attribution to workshops and artists, whereas the scientific assessment of their condition informs decisions on conservation and restoration treatments. Dendrochronology is the science commonly used to date the wood of panel paintings and establish its provenance. The first tree-ring studies on panel paintings took place in the 1960s [2]. A wealth of information has been gained about the scale of the north-European timber trade, the use of different wood species for painting supports, the evolution of woodworking and conservation techniques since the late Middle Ages, seasoning time, and the economy of wood resources in European workshops Case studies often provide exciting finds, such as timber supply areas that had not been reported before, suggesting a disruption of traditional trade routes in specific years, cheaper transport costs, or even tailormade trade alliances [10]

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