Analytical Techniques: X-radiography

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Author: Jessica Ford

Editors: Anne Schaffer, Kari Rayner

X-radiography is a non-invasive technique that directs x-ray radiation through a painting and onto film or an imaging plate, producing an image based on the radio-opacity of the materials. Many features that would otherwise be hidden or difficult to distinguish may be visually clarified, such as hardware and construction of frames or stretchers; canvas weave and tacking margins; brushwork and hidden paint layers; and damages/restorations (MacBeth 2012).

Normal light photo (left) and X-radiograph (right) of an oil painting on canvas, highlighting radio-opaque pigments used throughout the composition, as well as the canvas weave, tacks around the canvas margin, and the wooden stretcher support. Johannes Vermeer (Dutch, 1632–1675). A Maid Asleep, ca. 1656–57. Oil on canvas, 34 1/2 x 30 1/8 in. (87.6 x 76.5 cm). Metropolitan Museum of Art, Bequest of Benjamin Altman, 1913, 14.40.611. (Photo: Metropolitan Museum of Art)

Thread Counting

Thread counting has long been performed as a way to document and compare canvases. In more recent years, an algorithm has been developed to automate thread counting and reliably weave-match canvases cut from the same bolt of cloth (Van Tilborgh et al. 2012). This automated technique can be performed using normal light imagery of an unlined painting’s verso; x-radiography provides the opportunity to apply automated thread counting and weave matching to lined canvases.

References

MacBeth, R. 2012. The technical examination and documentation of easel paintings. In Conservation of Easel Paintings, edited by J. H. Stoner and R. Rushfield, 291–305. Abingdon, Oxon England: Routledge.

Van Tilborgh, L, T. Meedendorp, E. Hendriks, D. H. Johnson, C. R. Johnson Jr, and R. G. Erdmann. 2012. "Weave matching and dating of van Gogh’s paintings: an interdisciplinary approach." The Burlington Magazine 154 : 112–122.