Tomba del Banchetto per l’Eternità in the Roman necropolis of Cuma: new insights on the polychromy and production technology of decorated walls

International audienceThe city of Cuma represents the most ancient Greek colony of the western Mediterranean Sea, studied since 1994 from the archaeological équipe of Centre Jean Bérard, in collaboration with other Italian Institutions. The excavations carried out in the northeast side of the city unearthed a monumental Roman necropolis with funerary mausoleums, tombs and isolated enclosures. Recent surveys performed in 2018 revealed the presence of the tomb MSL73101 (Tomba del Banchetto per l’Eternità; end of 2nd - first half of the 1st century b.C.), a hypogeum chamber tomb with vaulted ceiling built with tuff blocks. The tomb was decorated with a banquet scene; the lunette of the southern wall reported a scene with a banquet preparation whereas landscape depictions with a floral frieze in the upper part decorate the side walls. The vault, also decorated, is painted in yellow and pink colours while the walls below the cornice are characterised by an intense red. In the tomb three funerary beds were preserved along with a table, reproducing a sort of triclinium. The exceptional nature of the discovery is due to the peculiar decorative scheme, representing one of the rare coeval examples of figurative representations both in domestic and funerary contexts. Despite the evidences of a past plundering, the architectural scheme and the refined representations suggest the high social level of the dead, offering important cues for the reconstruction and the artistic evolution of the Cuman paintings. In-situ non-destructive analyses and samplings of mortar fragments were performed in order to define: a) the type of pigments used for decorating the tomb; b) the production technology of wall paintings and mortarbased support. Multispectral images, Fourier Transform Infrared Spectroscopy and Raman spectroscopy performed on frescoes samples allowed defining the composition of pigments used for painting the tomb. Red ochre, hematite, yellow ochre, kaolinite, carbon black and calcite were recognised by using a no-destructive approach as principal types of pigments. Moreover, vibrational spectroscopy disclosed the composition of the underlying support, made of lime-based plasters. In order to better understand their production technology, minero-petrographic analysis (Polarised Light Microscopy -PLM-, Scanning Electron Microscopy -SEM- and Energy Dispersive Spectroscopy EDS-) were also performed on plasters fragments, highlighting a multi-layer technology. In the lower part of the walls, lime mortars with cocciopesto adhere on the tuff blocks (rinzaffo/arriccio layers) or constitute the intonachino layer, likely due to the good hydraulic properties of such a type of mortars in humid and wet environments. On the other hand, the upper part of walls arriccio is absent or was not sampled whereas a thick and white intonachino layer constituted by lime binder containing sporadic grains constitutes the support of preparatory and painting layer. On the vault, multi-layered plasters consisted of a thinner grey arriccio layer (ca. 0.5 cm), made with lime binder and fine volcanic sand as aggregate, covered by a white intonachino layer with rare calcareous grains, overlaid by the preparatory and pictorial layer