Arie Wallert

... 56 5 Language Text: English References: 36 notes Subject Keywords English: Painting; Technique; Material; History; Oil painting; Pigment; Medium; Support; Preparation; Preliminary drawing; Ground; Panel; Support wood; Analysis; X ray; Radiography; Infrared reflectography ...

James McNeill Whistler was meticulous in his choice and use of oil painting materials. The late 1870s and early 1880s seem to introduce a period of experimentation, characterised by strongly diluted paints in the full-length portraits of that period, and resulting in a richer language in paint handling in Whistler's later works. Through scientific analyses combined with art-historical research, as well as material from the Whistler correspondence, this paper addresses the process of experimentation as well as the visual impact of Whistler's exploitation of the increased fluidity and transparency of his oil paints, and of his choice of unusual materials to enhance these effects. The research centres on Whistler's full-length portrait Arrangement in Yellow and Grey: Effie Deans (Rijksmuseum, Amsterdam) as a key case study.

ABSTRACT Information on the creation of a painting lies usually hidden under the surface. A painting's substructure may include the underdrawing, underpainting, modifications to the initial setup (or pentimenti), and sometimes even abandoned compositions. Traditionally, the study of these characteristics relies on penetrative, two-dimensional imaging techniques (infrared reflectography, x-ray radiography) complemented with selected paint crosssections. The limitations of this approach are twofold. First, it can be difficult to combine data from cross sections with two-dimensional images, because of poor redundancy of both methods. Second, cross sections involve destructive sampling of the paint layer. This paper introduces synchrotron radiation computed micro-laminography in the study of paintings. The technique allows for three-dimensional imaging of the paint stratigraphy in a nondestructive manner, enabling the imaging of paint layers, their interfaces, the ground, and carrier. The technique is demonstrated on a test painting, and its interest to curators and conservators of painting collections is discussed.

ABSTRACT The characterisation of the microstructure and micromechanical behaviour of paint is key to a range of problems related to the conservation or technical art history of paintings. Synchrotron-based X-ray laminography is demonstrated in this paper to image the local sub-surface microstructure in paintings in a non-invasive and non-destructive way. Based on absorption and phase contrast, the method can provide high-resolution 3D maps of the paint stratigraphy, including the substrate, and visualise small features, such as pigment particles, voids, cracks, wood cells, canvas fibres etc. Reconstructions may be indicative of local density or chemical composition due to increased attenuation of X-rays by elements of higher atomic number. The paint layers and their interfaces can be distinguished via variations in morphology or composition. Results of feasibility tests on a painting mockup (oak panel, chalk ground, vermilion and lead white paint) are shown, where lateral and depth resolution of up to a few micrometres is demonstrated. The method is well adapted to study the temporal evolution of the stratigraphy in test specimens and offers an alternative to destructive sampling of original works of art.