Archaeometric Study on Roman Painted Terracottas from the Sanctuary of Hercules in Alba Fucens (Abruzzo, Italy)

Gilda Russo,Caterina De Vito,Aida Maria Conte,Laura Medeghini,Silvano Mignardi,Emanuela Ceccaroni

doi:10.3390/min12030346

Abstract

In a period spanning from the 7th to the 1st century BC, the exterior surfaces of civil and sacred buildings in Italy were mainly decorated with terracottas. The aim of this study is to determine the skills and technological level reached by ancient manufacturers of painted ceramics from the sanctuary of Hercules in the archaeological site of Alba Fucens (Abruzzo, Central Italy). A multi-analytical approach including X-ray Powder Diffraction (XRPD), µ-Raman and portable X-ray fluorescence (pXRF) was applied to determine the mineralogical composition of terracotta samples and to identify the pigments decorating the ceramics. The studied terracottas were decorated using valuable pigments such as Egyptian blue as well as a palette of colors common in the Roman period from the 3rd to the 1st century BC. The mineralogical composition of the ceramics allows estimating a firing temperature lower than 800 °C. Finally, a local origin of raw materials is suggested by the presence of alluvial and lake deposits outcropping in the Fucino area.

Highlights

Ceramic artifacts are common in archaeological sites as they are generally resistant to alteration and weathering
The samples were analyzed by a multi-analytical approach, including portable X-ray fluorescence, X-ray powder diffraction (XRPD), and μ-Raman spectroscopy
The X-ray Powder Diffraction (XRPD) analysis allowed the identification of the minerals that compose the ceramic body

Summary

Introduction

Ceramic artifacts are common in archaeological sites as they are generally resistant to alteration and weathering. Ancient ceramics had different functions: cult objects, decorations, vessels, refractory materials, and building materials [4,5]. Between the Archaic and the Late Republican period (7th–1st century BC) in Italy, terracotta (or fired clay) was the main material used for decorating the exterior surfaces of civic and sacred buildings. Painted revetment plaques in terracotta were nailed to facades in stone or wood, and the material was used to cover ceiling beams or columns. In preparation for painting, and as a protection against weathering, the upper surfaces of architectural terracottas were usually refined with a fine slip of diluted clay. After air-drying, clay-based colors (essentially colored slips) were applied to the visible surface with brushes. The surfaces could be further refined with pigments, dyes, and gold leaf attached with an organic binder.

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