Climate induced deformation of Panel Paintings: experimental observations on interaction between paint layers and thin wooden supports

This work describes the experimental evidence of the deformation induced on a XVI century panel painting by climate uncontrolled fluctuations and on structural replicas under controlled laboratory conditions. The objects under measurement have a very thin wooden support (6 mm), caused by thinning and cradling of the original artefact during a restoration made at the beginning of the XX century. This kind of artefacts are very susceptible to suffer mechanical damage. The data of experiments carried out on the panel and in laboratory conditions show a characteristic behavior, similar to bimetallic strip warp and an interaction between hygroscopic asymmetry and mechanical asymmetry, inducing a peculiar stress dynamic in the interface wood-paint layer during climate fluctuations. In collaboration with the conservators involved in the restoration process, the effect of buffer hygroscopic systems on the warping has been studied.