Compréhension de la dégradation matérielle des brocarts appliqués sur des sculptures en bois de la fin du Moyen Âge (contrat Université Grenoble Alpes)

Lieu : CEA/ARC-Nucléart. Profil recherché : chercheur reconnu, titulaire d’un doctorat. Durée du contrat = 18 mois. Candidatures avant le 15 juin 2019.

Contact : Karine Froment, ARC-Nucléart, tél. 04 38 78 40 50, karine. froment@cea. fr

Context and state of the art

Applied brocades” are decorations in light relief intended to imitate on a painted or carved support the silks embroidered with gold or silver threads, worn by the nobility during medieval times. Native of northern Europe, this complex polychromatic decoration technique quickly spread to works produced in the rest of Europe during the fifteenth and sixteenth centuries.

The composition of the decors of “applied brocade” has been the subject of several specialized scientific publications and articles in the field of conservation – restoration. This work showed a homogeneity in the use of the tin sheet but also a diversity of composition for the part corresponding to the mass of the decoration based on organic materials (drying oil, wax, wax / oil mixture, etc.) charged or not with minerals (lead, pigments …). This documentation mainly concerns works from northern Europe, and was used as a basis for the studies already carried out and supervised by the GIP ARC-Nucléart, in collaboration with the ESRF, Institut Néel (CNRS-UGA) and LAMS (CNRS-Sorbonne Université) of the year 2014 on works produced in the Old Duchy of Savoy.

Applied brocades have been recently identified on a corpus of wood and stone sculptures produced in the Old Duchy of Savoy around the years 1480 – 1530. They were the subject of a physico-chemical study which took place between September and December 2014, and then in 2015 (Pouyet, Guiblain, Martinetto, Walter, Cersoy, Cotte, Sept-2014, 2015), presented at the MSH Alpes symposium in December 2015. This work combined analysis i) in situ ones by Xray diffraction and fluorescence, and ii) on samples by visible, electronic, infrared and X-ray microscopy. This combination of techniques made it possible to localize and identify the ingredients (organic / inorganic , degraded / not degraded) composing the various stratigraphic layers of the “applied brocades”, in order to rediscover the know-how applied to each of the sculptures studied. In addition, the combined analysis of inorganic materials using more advanced techniques, via μXRD and μXANES, and organic materials, via μFTIR, resulted in the identification and localization of the degradation materials.

Moreover, to our knowledge, there is no work on the understanding of the degradation of these materials in their environmental context (humidity, temperature, UV radiation, overpaintings, …), their possible interactions, and they raise a real difficulty when conservators-restorers are confronted with the need to intervene on this type of decor to stabilize and enhance them.).