Multi-analytical study of mural paintings from a Republican house from 1st BC in Ostia

Ostia Antica, the ancient port of Rome, is overflowing with many remains, proofs of the greatness and the important activity of this area. Among them, the Schola del Traiano, along the Decumanus Maximus in the neighbourhood of Porta Marina , presents a complex history. In addition to the excavation by archaeologists of three successive buildings on this parcel, the discovery of an uncommon dwarfs frieze (dating from 40 - 30 BC) brought attention. Usually depicted in decadent or ridiculous scenes, dwarfs are pictured here in scenes of daily life. This frieze is surrounded by other very elaborated friezes and tiles: Green and red masks friezes, dentils, the dwarfs frieze, a vegetal frieze, coloured tiles, a fruits frieze, and big red tiles surrounded by coloured lines combine to form a colourful room decoration. To deepen our understanding of this particular decor, various complementary analytical techniques were used: Raman spectroscopy, MA-XRF, hyperspectral imaging and digital microscopy. Besides the identification of the pigments used for each colour (Egyptian blue, cinnabar, iron oxide, chalk, ...), these techniques also allow to compare the different decoration parts together and to highlight common points and differences between them, in term of chemical composition but also concerning the decor elaboration and the successive steps in the painting implementation.