Counting Vermeer


2.1 The history of X-radiographs in the study of paintings

Shortly after the discovery of X-rays in 1895 by the German physicist Conrad Wilhelm Röntgen (1845-1923), the first X-radiographs of art objects were made. In his experiments, Röntgen subjected wooden blocks painted with lead-white paint to X-rays. However, it was Walter König (1859-1936), a professor in Frankfurt, who in 1896 would make the first X-radiograph of an actual painting. Alexander Faber, a medical radiologist in Weimar, also examined several paintings with X-rays. In 1914, apparently unaware of the work of König, he took out a patent on the X-radiography of oil paintings.1 The overall impact of Faber’s patent, however, was limited.2 During World War I, X-radiography became a widespread tool for medical purposes and many doctors with portable X-ray machines would also successfully employ the technique in the examination of paintings. Those include Leo Gerard Heilbron (1882-1960) in Amsterdam, André Chéron in Paris and Guido Holzknecht (1872-1931) in Vienna.3 In 1924, the Bayerische Staatsgemäldesammlungen in Munich, aware of Faber’s patent, was the first museum to install an X-ray machine and in the years that followed would systematically X-ray paintings. As a result a fine was imposed on the museum, leading to a long conflict over royalty payments. The dispute was eventually resolved in 1931 when Philips and Siemens-Reiniger-Veifa bought Faber’s licensing rights and successfully launched an X-ray machine onto the market specifically designed for the examination of paintings.4

Another crucial turning point in the use of X-radiography in the study of paintings came with art historian Alan Burroughs (1897-1965) at the Fogg Art Museum at Harvard University. In 1925 he received a grant from Harvard University to investigate the use of X-rays in the study of paintings. This led to the start of an archive of X-radiographs of paintings with secure attributions, which Burroughs referred to as shadowgraphs. This archive was to serve as references/standards for authentication and attribution of pictures. The archive was not limited to X-radiographs from American collections, but also included X-rays of masterpieces from many European museums. With his portable X-ray machine, Burroughs embarked on several expeditions to Europe. In 1926 he X-rayed paintings in the Louvre in Paris, and the Kaiser-Friedrich-Museum in Berlin, and a year later, in collections in Belgium and England, followed by the National Gallery in London in 1929-1930.


Alan Burroughs (applying X-radiography to examine a work of art), 1941. (Photo: HUP Burroughs, James (1) olvwork290891, Harvard University Archives)

During the late 1920s and 1930s, as more and more museums around the world had access to X-ray facilities, Burroughs traveled less, and instead commissioned images from European X-ray specialists, including the Dutch scientist and conservator Martin de Wild (1899-1969), the art historian Johannes Wilde (1891-1970) in Vienna, and the German painter and conservator Kurt Wehlte (1897-1973).5
The first X-ray examinations of paintings had many positive responses and the technique was sometimes believed to be the solution to all questions concerning forgeries and uncertain attributions. In the 1926 article ‘Solving the problems of art by X-ray’, Marion Todd excitedly reported that Burroughs’ X-ray discoveries ‘betray fakes and copies that critics have never been able to detect’ and marveled over the ability of X-rays to detect ‘masterpieces which later artists have covered over with mediocre paintings’.6 A Dutch newspaper in 1928 claimed that X-rays laid bare ‘the deepest secret of a painting’ and that ‘the history of art would have to be rewritten’.7

Not everyone was as convinced of the use of X-rays in the examination of paintings. Noteworthy is the statement made by the influential art historian and director of the Kaiser-Friedrich-Museum, Wilhelm von Bode (1845-1929). Bode compared the use of X-rays to that of a ‘divining rod’ and denounced it as nonsense: ‘Alles Mumpitz!’.8 Many opponents of X-rays were art dealers, possibly fearful that information gained from X-radiographs would affect the value of an artwork.9 In the famous Hahn versus Duveen trial, the English art connoisseur/dealer Sir Joseph Duveen bluntly stated: ‘I don’t believe in X-rays’.10

Burroughs himself emphasised that although X-radiographs were of great importance in the investigation of pictures, they cannot provide exact answers. In his 1938 publication Art Criticism from a Laboratory, in which different topics in his studies with X-radiographs were compiled and problems he had explored over the years were re-evaluated, the art historian stated: ‘Physical evidence may have a certain bearing on problems of authenticity, but may also be subject to a type of personal evaluation which removes it from the field of impersonal evidence’. Almost regretfully the researcher declared: ‘Even the seemingly impersonal research undertaken with the aid of X-rays usually becomes a matter of interpretation’.11


X-ray set-up in Martin de Wild's studio with a photographic dark room for processing film in the rear. (Photo: ArchiefA.M. de Wild, RKD; box 9)


1 C.F. Bridgman, ‘The Amazing Patent on the Radiography of Paintings’, Studies in Conservation 9 (1964), pp. 135-139.

2 M. Graf von der Goltz, Kunsterhaltung-Machtkonflikte. Gemälde-Restaurierung zur Zeit der Weimarer Republik, Berlin 2002, pp. 90-92.

3 G. Vanpaemel, ‘X-rays and Old Masters. The Art of the Scientific Connoisseur’, Endeavour 34 (2010), no. 2, pp. 69 -74, esp. p. 71.

4 Graf von der Goltz 2002 (note 2), p. 91.

5 F.G. Bewer, A Laboratory for Art. Harvard’s Fogg Museum and the Emergence of Conservation in America, 1900-1950, Cambridge (MA)/New Haven 2010, pp. 101-103, p. 198, p. 305 (note 239).

6 M. Todd, ‘Solving the Problems of Art by X-ray’, The American Magazine of Art 17 (1926), pp. 578-581.

7 ‘Het geheim der oude schilderijen’, Algemeen Handelsblad, March 11, 1928.

8 'Bode über "Kunstexpertise durch Röntgenstrahlen"’, Der Kunstwanderer 2 (1921), p. 253, in: (date consulted: March 2017)

9 Bewer 2010 (note 5), pp. 102-103.

10 Andrée Hahn sued Duveen for slander after the art dealer claimed that the painting Hahn offered for sale to the Kansas City Art Museum was not an original Leonardo da Vinci. Duveen declared that the painting was a fake (without even having seen the picture), which made the sale of La Belle Ferronnière impossible. Despite his earlier distrust of X-rays, towards the end of the trial Duveen would go to great lengths to have an X-radiograph of the Louvre version of La Belle Ferronnière admitted as evidence. Duveen even chartered a plane to collect the X-radiograph from the Fogg Art Museum in Cambridge. In: J. Brewer, The American Leonardo: A 20th Century Tale of Obsession, Art and Money, London 2009, p. 95. Burroughs was called as an expert in the case and was asked to compare the X-ray images of the two versions. For this comparison, see: Bewer 2010 (note 5), p. 104.

11 A. Burroughs, Art Criticism from a Laboratory, Boston 1938, pp. XIV-XV.

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