A RAMAN/SANS/XRD STUDY ON THE STRUCTURE-PROPERTY RELATIONSHIP OF OUTDOOR AND INDOOR ROMAN WALL PAINTINGS

Determination of the chemical composition of different parts of the wall paintings (pigments, mortars and binders) allows extracting information about technology of preparation of the artefact. Herein we present a multimethodological characterization of wall paintings from a Roman Archeological sites from Cuma, focusing on differences between indoor (domus) and outdoor (Temple) fabrication. Both pigments, binders and mortars were studied via a combination of destructive/microdestructutive (mass spectrometry, ionic chromatography, ICP-based techniques) and non-destructive (Raman microscopy, X-ray diffraction and SANS) methodologies. Particularly, the systematic presence of dolomite only in temple mortars suggests an intentional use of such limestone for outdoor fabrication. Differences between temple and domus extends also to binder composition: proteinaceous binders in domus (possibly egg [3] and animal glue), whereas in TCP no protein was detected but some fat acids (probably from animal fat). Ultimately, the multimethodological study allowed an overall picture of the components and technology of the paintings from fabrications with different use, proposing distinct engineering choices for indoor and outdoor walls. References [1] Cartechini L., Pucci P., Sgamellotti A., Marino G., Birolo L., “Proteomic strategies for the identification of proteinaceous binders in paintings” Analytical & Bioanalytical Chemistry 395(7), 2009, 2269-2280. [2] Gelzo M., Grimaldi M., Vergara A., Severino V., Chambery A., Dello Russo A., Piccioli C., Corso G,. Arcari P. "Comparison of binder composition in Pompeian wall painting styles from Insula Occidentalis" Chemistry Central J. 8(65), 2014, 1-10. [3] Vinciguerra R, Galano E, Vallone F, Greco G, Vergara A, Bonaduce I, Marino G, Pucci P, Amoresano A, Birolo L, “Deglycosylation Step to Improve the Identification of Egg Proteins in Art Samples” Analytical Chemistry 87 (20), 2015, 10178-10182. Acknowledgements This work was financially supported by Distretto ad Alta Tecnologia dei Beni Culturali (DATABENC scarl), progetto SNECS. “Soprintendenza Speciale per i Beni Archeologici di Napoli e Pompei” – Ufficio Archeologico di Cuma - Dr Paolo Caputo is also acknowledged.