# X-Radiography, Pentimenti and Reused Supports > A radiograph is a density map of lead, not a picture of the layers beneath. It reads the support and the changes of mind, and a forger who knows that composes around it. > The Study - 2026-08-02 > Canonical HTML: https://iconotheca.com/study/x-radiography-pentimenti-and-reused-supports/ ## Key points - Automated weave mapping of twenty-nine Vermeer canvases found four with almost identical thread counts that came from four different bolts of cloth. - Cusping and weft anomalies visible in a radiograph show whether a canvas was primed while stretched and whether an edge has been cut down. - Changes of mind are evidence that a composition was being invented, but the National Gallery of Art's Girl with a Flute contains revisions and is not by Vermeer. - Both van Meegeren and Beltracchi scraped old canvases, and Beltracchi composed around the surviving image so that the radiograph would look innocent. ## What the plate actually records ## The support testifies before the image does ## Changes of mind evidence invention, and stop short of a name ## Reuse cuts both ways ## What radiography cannot reach The most valuable thing a radiograph tells you is usually not about the painting but about the object carrying it: how the canvas was woven and stretched, whether an edge has gone, what has been filled, and whether somebody painted here before. Read in that order, it constrains an attribution powerfully and cheaply. Read as a window onto the artist's mind, it flatters the reader, and it flattered two of the twentieth century's most successful forgers, one of whom composed his picture around the plate he knew a museum would eventually take. ## Questions **Why is thread counting done from a radiograph rather than from the back of the canvas?** Because the lead-bearing priming has settled into the interstices of the weave and makes individual threads visible as density variations across the whole picture surface. The back of a lined painting is usually the lining canvas, and even an unlined back gives no information about the areas covered by the stretcher bars. **Does cusping prove that a canvas has not been cut down?** It proves that the edge where the cusping appears was stretched and primed in that position. Absence of cusping on one edge is a strong indication that the edge has been trimmed, though lining, restretching and the loss of tacking margins can also remove the evidence, so the treatment history must be established first. **If a radiograph shows an entirely different composition underneath, does that mean the picture is autograph?** No. It means the support was used twice. That is compatible with an artist reworking his own canvas, with a workshop economising, and with a forger scraping down an old picture to acquire a period support. The question to ask is whether the buried image is stylistically earlier or later than the visible one. **Can macro X-ray fluorescence replace radiography?** It supplements it. Scanning macro-XRF maps specific elements and can therefore reconstruct a hidden composition in something close to colour, as on Goya's Satue portrait, while radiography gives a single integrated density image that reads the physical support, the joins, the fills and the losses far more directly. Museums that can afford both run both. ## Sources - [1] Walter Liedtke, C. Richard Johnson Jr. and Don H. Johnson, 'Canvas Matches in Vermeer: A Case Study in the Computer Analysis of Fabric Supports', Metropolitan Museum Journal 47 (2012), pp. 101-108. - [2] Marjorie E. Wieseman, Alexandra Libby, E. Melanie Gifford and Dina Anchin, 'Vermeer's Studio and the Girl with a Flute: New Findings from the National Gallery of Art', Journal of Historians of Netherlandish Art 14:2 (2022). - [3] BBC News, 'X-ray reveals hidden Goya painting', 22 September 2011. - [4] Martin Bailey, 'Hidden Goya portrait discovered', reproduced by the American Institute for Conservation, 15 November 2011 (scanning macro X-ray fluorescence; restorer Anna Krekeler). - [5] Bernard Keisch, The Mysterious Box: Nuclear Science and Art, US Atomic Energy Commission (Project Gutenberg edition), including the radiograph of the Emmaus showing the scraped original. - [6] Diana Blumenroth, Jenny Nieberle and Gunnar Heydenreich, 'Moeglichkeiten und Grenzen kunsttechnologischer Untersuchungen: Heinrich Campendonks Gemaelde im Kontext des Beltracchi-Faelschungsskandals', CICS, Fachhochschule Koeln, 2014 (Beltracchi on composing around the X-ray; Otto Wacker trial). - [7] Joyce Plesters, 'Samson and Delilah: Rubens and the Art and Craft of Painting on Panel', National Gallery Technical Bulletin 7 (1983), pp. 30-49. - [8] Paul Jeromack, 'Dendrochronology and infra-red photography are giving surprising results among Netherlandish paintings at the Metropolitan Museum', The Art Newspaper, 31 March 1993.