Resumo: Macroscopic X-ray fluorescence (MA-XRF) and powder diffraction (MA-XRPD) are forms of non-invasive hyperspectral imaging that allow to obtain information on painted works of art, often in the form of elemental or chemical images. By means of these methods the following can be done:
- revisualization of overpainted representations, revealing early stages of the creative process or intentional alterations of the composition done during the lifetime of the artwork;
- (highly specific) identification of the pigment types used and the pigment subtypes present, providing opportunities to study the provenance and authenticity of works of art; and
- identification of the nature and distribution of secondary products, formed on the paint surface by degradation of the original painting materials.
In the past decade we have imaged a variety of (renowned) paintings, mainly in European museums. In a number of cases, macro-scale information was combined with (X-ray based) micro- and nano-analysis of paint samples,
After describing the principles of MA-XRF and MA-XRPD and an outlining their strong and weak points, several case studies will be discussed, including
(a) imaging the panels of the 15th c. Ghent Altarpiece (~1432) by Jan Van Eyck, Flemish masterpainter of the 15th century,
(b) scanning highlights of 17th c. Dutch art such as Rembrandt’s Nightwatch (1643) and
(c) analyzing the degradation of pigments in The Scream (1910?), masterpiece of Norwegian painter Edvard Munch.
He obtained a PhD in Analytical Chemistry in 1989. Since then, he has been actively making use of strongly focused X-ray micro- and nano-beams, produced in large accelerator complexes called Synchrotron Storage Rings, for non-destructive materials analysis. A combination of X-ray fluorescence spectrometry, X-ray absorption spectroscopy and X-ray diffraction usually is employed to characterize these materials in 2D or 3D imaging mode.
He also applies these techniques for better understanding naturally occurring alteration and degradation processes in cultural heritage materials such as historic glass, inks and painters’ pigments. Next to microscopic investigations of small samples, non-invasive macroscopic imaging is performed using mobile scanning equipment. Such imagery has proven to be useful for art historians and art conservators in order to understand better both the past and future of works of art.
K. Janssens is (co)author of ca 400 scientific papers (h-index: 55) and has served as (co)editor of four scientific books, dealing with non-destructive analysis in the cultural heritage area. He has organised several conferences on analytical chemistry, X-ray micro beam analysis and its applications. From 2015-2021 he was vice-dean of the Faculty of Science and currently vice-chair of the Department of Physics of the University of Antwerp. He is a member of the Council of the European Synchrotron Radiation Faculity (ESRF, Grenoble, FR) and of the Belgian Federal Council for Research Policy.
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