A non-invasive multi-analytical approach supporting archaeological reconstruction: the investigation of blue pigments uncovered at Villa romana di Lio Piccolo (Cavallino - Treporti, Venice)".

Abstract

The current research work focuses on the study of some of the three thousand fragments of fresco found in an underwater archaeological excavation located in the Northern Lagoon of Venice and, in particular, on the use of non-invasive analytical techniques for a quick recognition of pigments. Indeed, the application of an in situ protocol to easily identify through a scientific and statistical approach the palette used in the past. Objects studied come from the site No. 181 of Lio Piccolo, located in Treporti near the inhabited area Lio Piccolo, in the Rigà canal. Here the remains of the Roman villa were found, together with a large number of fragments of wall paintings attributable to the early and middle imperial age (I-II centuries A.D.). The Lio Piccolo Villa represents the unique known example of a Roman villa located in the Northern Lagoon of Venice. The corpus of painted wall fragments, consisting of 2612 units, presents a great variety of colours used and numerous decorative types. Furthermore, the type and quality of the recovered ceramic material and other decorative apparatuses such as marble and mosaics seem to support the thesis that it could be an urban-rustic villa of the imperial era and of a medium-high social level. The approach here investigated is multidisciplinary: it takes inspiration from archaeological studies conducted previously and proposes analytical studies on one of the pigments used in the realization of these frescoes and in particular the blue pigment. This work is mainly divided into two macro-sections. The former briefly focuses on the archaeological site n. 181 of Lio Piccolo, from which some of the fresco fragments examined come. The latter is an analytical-scientific approach, that aims at the characterization and identification of the blue pigment used in the backgrounds and/or in the realization of some details. Historically, among Roman pigments there are many shades and varieties of blue colours. The most stable and used for murals, known already by Egyptian artists, was the Egyptian blue. In our case, in which we have a considerable amount of samples, it was decided to select some pieces and to use and compare non-invasive spectrophotometric techniques: Fiber Optic Reflectance Spectroscopy (FORS) and colorimetry. This approach wants to investigate the possibility to understand if a fragment with blue painted areas belongs to a background or to a detail, just on the base of the analytical results. To support the data so obtained, Raman spectroscopy and Total Attenuated Reflectance (ATR) Fourier Transform Infrared spectroscopy (FTIR) analyses were performed. Thus, this research fulfils the need to find as an analytical approach as possible to be applied for the identification of ancient artistic techniques and archaeological reconstruction, especially when it is faced a situation with a considerable number of fragments and it is not possible to carry out a targeted analysis on all of them.