Silvia Rita Amato

The Victoria and Albert Museum holds an important portrait of the Jamaican scholar and writer Francis Williams (c.1692/97–1762), portrayed as a scholar in his study. It is believed to have been painted around 1745 by an unknown artist, but the circumstances of its production are unknown. A technical examination of the painting was performed using x‐radiography and infrared reflectography (IRR), macro x‐ray fluorescence scanning (XRF), digital microscopy, scanning electron microscopy with energy‐dispersive x‐ray spectroscopy (SEM–EDX) and reflectance imaging spectroscopy in the short‐wave infrared (SWIR). XRF, IRR and reflectance imaging spectroscopy in the SWIR revealed the distribution of inorganic pigments including lead white, earth pigments, Prussian blue, vermilion, orpiment (or pararealgar) and bone or ivory black. Pentimenti and a different sketched landscape were observed in the IRR images, highlighting changes in the final composition. Three‐dimensional (3D) digital microphotography provided additional historical and contextual information through the observation of book titles and details. High‐resolution digital imaging complemented analytical data. Results of the technical examination revealed the material composition and the development of the painting, contributing to shed new light on the production of the portrait, the history and significance of the portrait.

This paper presents results from the examination of a set of experimental samples using fibre optic reflectance spectroscopy (FORS) and diffuse reflectance imaging spectroscopy in the short-wave infrared (SWIR) range, combined with statistical analysis of the data for the discrimination and mapping of poppy and linseed oil. The aim was to evaluate the efficacy of this non-invasive approach for the study of paint samples with a view to the application of the method for characterisation of the two drying oils in painted art. The approach allowed discrimination between the two drying oils based on FORS spectra and the hyperspectral cube, indicating the influence of the spectral region around 1700 nm on the statistical discrimination based on the anti-symmetric and symmetric first overtone stretching of methylenic CH₂ groups. This method is being studied as a potential non-invasive method of organic analysis of oil types that have formerly been studied using gas chromatography-mass spectrometry (GC-MS), which requires micro-samples.

The paintings by Édouard Manet in The Courtauld Gallery Déjeuner sur l'herbe (1863–68), Marguerite de Conflans en Toilette de Bal (1870–1880), Banks of the Seine at Argenteuil (1874), and A Bar at the Folies–Bergère (1882) were investigated for the first time using a range of non‐invasive in situ analyses. The aims of the study were to investigate the painting techniques and materials used for this group of works and to critically evaluate the technical evidence derived from the integrated use of imaging techniques and portable spectroscopic methods in this context. The paintings were investigated by means of macro X‐ray fluorescence (MA‐XRF), reflection spectral imaging, portable UV–Vis–NIR spectroscopy, portable Raman spectroscopy, and reflection FTIR. MA‐XRF and reflection spectral imaging allowed visualising elements in the compositions that were not visible using traditional methods of technical study. For example, MA‐XRF analysis of Déjeuner sur l'herbe revealed elements of the development of the composition that provided new evidence to consider its relationship to other versions of the composition. The study also highlighted questions about the interpretation of elemental distribution maps and spectral images that did not correspond to the reworking visible in X‐radiographs. For example, in A Bar at the Folies–Bergère Manet made numerous changes during painting, which were not clearly visualised with any of the techniques used. The research has wider implications for the study of Impressionist paintings, as the results will support technical studies of works by other artists of the period who used similar materials and painting methods.