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International audience; This article describes the experimental devices and the processes used to study the hygromechanical behaviour of a historic painted wooden panel (La Sainte Trinité couronnant la vierge, 1516, anonymous, Fabre Museum of Montpellier). A climate showcase was designed for in-museum use, with two glasses allowing visitors as well as scientists to observe both sides simultaneously. The evaluation of the hygroscopic behaviour was done by measuring relative humidity (RH), temperature and variations of panel weight. Variations of panel shape, strain and curvature were observed by two methods: locally with three pairs of displacement transducers fixed on the rear face, and over the entire panel surface by a non-contact optical technique, stereo mark tracking, used simultaneously on both faces. The correlation between local and whole-field measurements was very good. Continuous monitoring (several data per hour over three years) was required to observe the behaviour of the panel during imposed climate variations. The first test, detailed in this paper, was performed before frame removal and panel restoration. It consisted in a stabilization of the panel at 52% RH during 2 months and an increase to 63% RH during 3 months. The small amount of total mass variations, from 31.980 kg to 31.910 kg at 52% RH and 32.088 kg at 63% RH, could not be explained without taking into account the phenomenon of sorption hysteresis. The whole field relief measurement exhibited a concave shape with a maximum amplitude of 16 mm. It showed that shape deformation, ie out-of-plane displacement, was convex bending with a maximum deflection of 1.5 mm and a maximum strain of 0.1 %. Comparable local data had been obtained by the optical and DKs methods. DKs results were ten times more accurate than optical ones. The horizontal strain exhibited a global shrinkage during initial stabilization and a global swelling during RH increase. Heterogeneity of the strain field can be related to the cracks observed on the back face, and to the glued crossbeams. Assuming a linear relationship between swelling and moisture content, we expected, for a 0.6% increase of moisture content, a radial strain of 0.10% and a tangential strain of 0.22%. These results are higher than the ones measured, which can be explained by the cross bars glued on the boards and the cracks. This comparison will be continued for the next stages (crossbars removal, panel restoration).

L’exposition « Dans le Secret des œuvres d’art » présentée en 2018 au musée Fabre proposait au visiteur de découvrir l’étude matérielle et la restauration de plusieurs œuvres des collections du musée montpelliérain. L’objectif de l’exposition était d’apprendre au visiteur à observer la matière de l’œuvre et proposait ainsi un ensemble de médiums, huile sur toile, huile sur bois, dessin sur papier, fonte en bronze et toile libre en matériaux contemporains, comme autant de « cas » matériels à découvrir. La complexité de nombreuses opérations évoquées par l’exposition a impliqué un important usage des ressources du numérique. Des applications interactives, courts-métrages, modélisation 3D, vidéos pédagogiques et mapping étaient disséminés tout au long du parcours de visite, proposant un usage du numérique particulièrement pertinent, permettant de découvrir au plus près la singularité matérielle des œuvres exposées. The exhibition « Dans le Secret des œuvres d’art », which took place in 2018 at the musée Fabre, offered visitors to discover the material study and the conservation of several works from the collections of the Montpellier museum. The purpose of the exhibition was to teach the visitor to observe the material aspect of the artworks and offered a set of mediums (oil on canvas, oil on wood panel, drawing on paper, bronze cast and free canvas in contemporary materials), as material « cases » to discover. The complexity of many operations evoked by the exhibition implied an important use of digital resources. Interactive applications, short films, 3D modeling, educational videos and mapping were disseminated throughout the visit trail, offering a particularly relevant use of digital tools, allowing to discover as closely as possible the material singularity of the artworks on display.