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• Comprehensive study of an alleged forgery of a tempera painting on tile with apparently Botticelli features. • Pigments identification – i.e., iron oxide pigments, cinnabar, carbon black, and calcite) - by combined FORS and Raman spectroscopy. • Pigments mapping by SCM algorithm application to the multispectral image cube. • Colorimetric analysis to quantitatively evaluate the cleaning method and provide support for an informed restoration process. In this work, a tempera painting of uncertain attribution from the Uffizi Galleries was studied. The painting, which portraits a man with apparently Botticellian features, was probably created by one of the most skilled forgers of the early 20th century, Umberto Giunti. He used a flat tile as a support, covered with preparatory layers emulating a wall painting. To shed light on the authorship of the painting, it was crucial to investigate its composing materials, as well as the execution technique and the state of conservation. To this end, non-invasive spectroscopic and imaging optical techniques were applied. Specifically, VIS-NIR multispectral reflectography was used to reveal the presence of possible preparatory drawings, pentimenti and overpaintings. Raman and Fibre Optics Reflectance Spectroscopies allowed identifying the pigments used by the artist. Finally, colour variations due to the cleaning procedure were documented in order to provide a support for an informed restoration process. [ABSTRACT FROM AUTHOR]

• Combined imaging techniques yield to the identification and mapping of the main pigments used by Lorenzetti. • Reflectance imaging allows revealing hidden details and quantifying the colorimetric differences induced by the cleaning operation. • The micrometric thickness of the paint layers is visualized and measured by optical coherence tomography. • The Gaussian mixture model used for the post-processing of fluorescence life data is applied for the first time to discriminate retouched areas from the original painting. Paintings are complex multi-layered structures characterised by high compositional and structural heterogeneity. Therefore, a combined analytical approach is often required to overcome ambiguities in the interpretation of data acquired by an individual technique. In this paper, we applied three non-invasive imaging techniques for the study of a 14th-century altarpiece by Pietro Lorenzetti belonging to the Uffizi Galleries. In detail, we used reflectance imaging spectroscopy to identify and map the pigments, and reveal features not visible to the naked eye; to quantify the colorimetric differences induced by the cleaning; to visualise and measure the micrometric thickness of the paint layers. Then, we applied optical coherence tomography to visualise and measure the micrometric thickness of the material layers. Finally, we carried out fluorescence lifetime imaging to discriminate the pictorial integration from the original painting using a method never before applied to a work of art. The data was discussed within a multidisciplinary team of experts. [ABSTRACT FROM AUTHOR]

The analysis of archaeological mural paintings may provide relevant information on the artistic techniques and the pictorial materials used in the past, expanding the knowledge of customs and technologies of ancient societies. Given their location, fragility and value, it is generally required to analyze mural paintings in situ, avoiding contact measurements, sampling or pre-treatments. In this work, a number of polychrome fragments from two recently discovered Roman villas have been studied with three non-invasive techniques, making use of transportable devices: Macro X-ray Fluorescence (MA-XRF) elemental mapping, multispectral scanning reflectography, and Fibre Optics Reflectance Spectroscopy (FORS). Specifically, the MA-XRF elemental maps were compared with the spectral correlation maps (SCM) computed from the Vis-NIR images acquired with the multispectral scanner, with the aim of displaying the distributions of the different pictorial materials, while assessing the chemical composition of the pigments present. The combined application of the two former mapping/imaging techniques represents a valid tool for the chemical and spectral characterization of archaeological paintings, providing easy-to-interpret data for the professionals involved in the conservation of Cultural Heritage. [ABSTRACT FROM AUTHOR]