Wax finishing in Roman polychrome statuary: Ganosis on the colossal head from Dougga (Tunisia)

Abstract

• Ancient sources describe the recipes and cultural values of the wax finish of the statues, known as ganosis. • Recipes are described by Pliny and Vitruvius, but never archeologically attested. • Time-of-Flight Secondary Ion Mass Spectrometry analyses are performed on one Roman statue from Dougga. • The use of wax finish, following the ancient recipes, and the potential of the TOF-SIMS are demonstrated for the first time in the study of ancient polychromy of statues. The material evidence for the wax finish on ancient marble statues, known as ganosis, is scarce and controversial, although Greek and Latin sources describe the recipes and cultural value of this treatment. The surface treatment of a colossal Roman head from the Roman theatre of Dougga (Tunisia), dated to the end of the second century CE, is studied by a multi-analytical protocol (video-microscope, cross section, and time-of-flight secondary ion mass spectrometry of one sample). The results of this physico-chemical analysis and the comparison with ancient recipes, prove the use of ganosis on a Roman statue and explore, for the first time, the application of the recipes described in ancient sources. This result shows the potential of the Time-of-Flight Secondary Ion Mass Spectrometry analysis, detecting at the same time organic and inorganic materials and their stratigraphy, to study the ancient recipes.