Investigation of Ancient Wall Painting Fragments Discovered in the Roman Baths from Alburnus Maior by Complementary Non-Destructive Techniques

Ioana Maria Cortea,Ovidiu Țentea,Mihaela Dinu,Lucian Ratoiu,Luminița Ghervase

doi:10.3390/app112110049

Ioana Maria Cortea, Ovidiu Țentea + Show 3 more

Open Access

https://doi.org/10.3390/app112110049

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Abstract

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.

Highlights

Public baths played an important role in Roman culture and life
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)
FTIR spectra registered on all pigmented layers are dominated by the strong absorption bands of calcite (CaCO3)—characteristic IR absorptions associated with the fundamental vibrations of the carbonate group observed around ~1400 cm−1, 872 cm−1, and 712 cm−1 [22]

Summary

Introduction

Public baths played an important role in Roman culture and life. A remarkable expression of Roman hydraulic engineering, the use of public baths started to spread towards the end of the third century BC throughout the Roman Empire. According to the current state of research, within the Roman province of Dacia, almost 40 small baths have been discovered until now, located within the forts (praetorium) as well as in the civilian settlements (extra muros) [4]. Compared to other baths found in Moesia Superior, the ones in Dacia (a frontier province), are, in most cases, modest and relatively early structures built between the second century and first half of the third century. Monumental bath structures, which can be associated with an elite residence, are just the ones found at Apulum and at Ulpia Traiana Sarmizegetusa [4,5]

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