In this study, several wall painting fragments discovered in the Roman baths from the archeological site Alburnus Maior (Roşia Montană, Romania) were analyzed with the aim to investigate the material composition of both plasters and pictorial layers. Dated from the beginning of the second century AD, these rare findings stand among the oldest examples of preserved decorative polychrome paintings on plaster excavated thus far in the former territory of the Roman province of Dacia. A non-destructive multi-analytical approach based on complementary techniques was considered: Fourier transform infrared (FTIR) spectroscopy, X-ray fluorescence (XRF), X-ray diffraction (XRD), UV fluorescence, and hyperspectral imaging (HSI). The obtained results highlight a common Roman color palette mainly based on naturally occurring earth pigments. Red ochre, yellow ochre, manganese-rich ochres/wads, carbon black, and calcite were identified. A traditional two-layer sequence of plasters was found—arriccio (based on lime and siliceous sands), and intonaco (pure lime). The presence of an organic protein binder, identified via FTIR analysis, and sustained by combined imaging documentation, indicates that the pigments were applied a secco. The obtained results are discussed in relation to previous published data, and they can be considered as valuable archeological indicators that contribute to the understanding of the painting techniques and the materials used in the Roman provinces.

This article reports the first analytical study carried on some of the oldest surviving examples of Roman wall paintings, discovered so far on the Romanian territory. Dating back to the second century, these decorative polychrome wall painting fragments were found during an archaeological research carried at Ulpia Traiana Sarmizegetusa, and represent the first mural paintings ever found on site. A set of samples was analyzed using various non-destructive and micro-invasive techniques in order to investigate the material composition and explore the painting technique. The employed methodology allowed for an in-depth characterization of the color palette, generally based on mineral pigments such as red earth, celadonite, yellow ochre, calcite, and strontianite. The absence of organic binders and the possibility to differentiate specific spectral features infer the use of a fresco-secco technique. The results obtained provide important data regarding the artistic and technological skill of ancient painters in this part of the Roman Empire, and they significantly contribute to the research and conservation work carried out at this impressive archaeological site.