New uses and improvements of the Deformometric Kit to support study and conservation of panel paintings
Résumé
The Deformometric Kit (DK) is a measurement system able to give continuously and real time quantitative information on the deformational dynamic response of panel paintings and other cultural wooden objects when they are subjected to environmental hygrothermal fluctuations. Using two parallel transducers linking a pair of axes fixed to the back of a panel, both the linear extension and the mean curvature of a studied zone can be monitored. To date many applications on actual panel paintings have been performed both in churches and in museums. We have monitored crosses, altarpieces, triptychs, placed in their usual display locations. As result of these experiences, new questions arise also of concern related to curators and restorers needs. The presentation will focus on the most challenging measurement needs under current investigation: - Monitoring strains/stresses during handling and transportation, requiring a particular use of the DK. Some data have been collected during various panel paintings transportations and the results will be presented. - Developing the fixation system to make it as minimally invasive as possible. Presently the connection between the wooden support and the DK is ensured by screws that fasten the connection in a stable way and represent a safe system for the support and the painted layers too. However we know that the screws system is not always usable, because of conservation issues, or because of the general condition of the wooden support. So we need to design and develop alternative fixation systems, to be optimized according to individual situations. - Studying the use of DK for evaluating the strains imposed on the paint layer by the deformation of the wooden support. Due to ring curvature shear deformations are induced across the thickness as a result of the hygromechanical loading and of the wood anisotropy. Consequently, the extrapolation to the front (i.e. painted) face of the measurements made on the back is not straightforward and requires some calibration. The DK is a new powerful method for studying the deformational response of panel paintings and other cultural wooden objects. This presentation reports about new improvements, which will better support knowledge and decisions about conservation of Cultural Heritage, and also provide reference data for calibrating and validating numerical models.