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This paper presents results from ongoing investigations of soft and dripping oil paint in art works by CoBrA's Karel Appel (1921-2006) and Asger Jorn (1914-1973). The work is part of the PhD-projec ...

The painting C’est grace a nous by Asger Jorn shows unusually soft black paint with substantial delamination. To provide insight into the condition and conservation issues, samples were analysed using Fourier-transform Infrared Spectroscopy (FTIR), Direct temperature Mass Spectrometry (DTMS) and Scanning Electron Microscopy Energy Dispersive X-ray Spectroscopy (SEM-EDX). The results show that the oil medium of the black paint layer in contact with the zinc containing ground has contributed to the development of zinc fatty acid salts (zinc soaps). Examination of the painting confirmed that the paint delamination was mainly found where the black paint was unusually soft. The implications for delamination and considerations for a possible consolidation treatment of C’est grace a nous are discussed in the context of the analytical results.

Moisture is a driving factor in the long-term mechanical deterioration of canvas paintings, as well as for a number of physico–chemical degradation processes. Since the 1990s a number of publications have addressed the equilibrium hygroscopic uptake and the hygro-mechanical deformation of linen canvas, oil paint, animal glue, and ground paint. In order to visualise and quantify the dynamic behaviour of these materials combined in a painting mock-up or reconstruction, we have performed custom-designed experiments with neutron radiography and nuclear magnetic resonance (NMR) imaging. This paper reports how both techniques were used to obtain spatially and temporally resolved information on moisture content, during alternate exposure to high and low relative humidity, or in contact with liquids of varying water activities. We observed how the canvas, which is the dominant component in terms of volumetric moisture uptake, absorbs and dries rapidly, and, due to its low vapour resistance, allows for vapour transfer towards the ground layer. Moisture desorption was generally found to be faster than absorption. The presence of sizing glue leads to a local increase of moisture content. It was observed that lining a painting with an extra canvas results in a damping effect: i.e. absorption and drying are significantly slowed down. The results obtained by NMR are complementary to neutron radiography in that they allow accurate monitoring of water ingress in contact with a liquid reservoir. Quantitative results are in good agreement with adsorption isotherms. The findings can be used for risk analysis of paintings exposed to changing micro-climates or subjected to conservation treatments using water. Future studies addressing moisture-driven deformation of paintings can make use of the proposed experimental techniques.

Easel paintings on canvas are subjected to alteration mechanisms triggered or accelerated by moisture. For the study of the spatial distribution and kinetics of such interactions a moisture exposure chamber was designed and built to perform neutron radiography experiments. Multilayered sized and primed canvas samples were prepared for time resolved experiments in the ICON cold neutron beamline. The first results show that the set up gives a good contrast and sufficient resolution to visualise the water uptake in the layers of canvas size and priming. The results allow for the first time real time visualisation of the interaction of water vapour with such layered systems. This offers important new opportunities for relevant spatially and time resolved material behaviour studies and opens the way towards numerical modelling of the process. These first results show that cellulose fibres and glue sizing have a much stronger water uptake than the chalk–glue ground. Additionally it shows that the uptake rate is not uniform throughout the thickness of the sized canvas. With prolonged moisture exposure a higher amount of water is accumulating at the lower edge of the canvas weave suggesting a decrease in permeability in the sized canvas with increased water content.

Modern and contemporary art collections show an increasing number of paintings with softening oil paints, exudates, and even drips. Since 2013 the condition of the paints on ca. 100 paintings from ...

Hierarchical structures appear often in life and materials sciences, and their characterization profits greatly from imaging methods that allow seamless probing of various length scales without sacrificing image quality. X-ray tomography is particularly adept at probing 3D structures; however, zooming in on a region of interest results in a loss of quantitativeness of image contrast and suffers from artifacts unless a priori knowledge or assumptions about the sample are used. Here, we demonstrate a hybrid technique that exploits a micrometer-resolution overview to realize ab initio nanoscale interior tomography with quantitative contrast. In a study of avian eggshell, a model for bionanoporous materials, our approach reveals a complex arrangement of vesicles with sizes ranging from hundred nanometers to a few micrometers. We anticipate that such an approach can be widely adopted and benefited from at synchrotron and laboratory sources, for instance, where such zooming capabilities are already present or can be readily realized.