The deposition from the Cross in the church of Saint-Germain-en-Laye (France): A masterpiece of Romanesque sculpture? Materials characterization to solve a 20th c. mystery

Dating and authenticating stone-sculpted works of art is a challenging aspect of cultural heritage studies. In fact, it is often possible to provenance the rock, by comparison of petrological, mineralogical and geochemical data, but no dating of the sculpture can be obtained. Also, stylistic observations need to be considered with care. However, in the case of mastic incrustation sculptures, the applied polychromy can support dating studies, based on pigments and binders. In the church of Saint-Germain-en-Laye, a haut-relief representing the Deposition from the Cross is exposed. The calcareous slab is decorated with red and black mastics. It resembles closely the Deposition from the Cross in the transept of Parma Cathedral, dated 1178 and “signed” by Benedictus Antelami. However, the St-Germain Deposition appeared in 1994, when it was donated to the parish by the descendants of Julien Auguste Duperrier, marble worker and collector of Italian antiquities. His last trip to Italy took place in 1924. No information is available on his deal, neither on the transport means arranged, nor on the sculpture itself (author, contractor, date, etc.). Art historical and historical considerations propose either a 12th or 19th–20th c. context for the creation of the sculpture. Chemical analyses of the pigments and binders are therefore proposed to clarify the dating the work of art. Microscopic samples are characterized by a multi-analytical approach: vibrational spectroscopies and X-ray powder diffraction are used to characterize the rock and the polychrome mastic. The rock is identified as a micritic limestone, and shows sulphation issues. Through Raman scattering measurements, the pigments were identified: carbon in the black mastic, and a mixture of red lead and a modern synthetic pigment (PR49:1) in the red areas. This information sheds new light on the chronology and manufacture of the Deposition from the Cross of Saint-Germain-en-Laye. These results allow for a better definition of further lines of research, and to finally propose an authorship for the sculpture.