Development of a versatile XRF scanner for the elemental imaging of paintworks

Abstract

Scanning XRF is a powerful elemental imaging technique introduced at the synchrotron that has recently been transposed to laboratory. The growing interest in this technique stems from its ability to collect images reflecting pigment distribution within large areas on artworks by means of their elemental signature. In that sense, scanning XRF appears highly complementary to standard imaging techniques (Visible, UV, IR photography and X-ray radiography). The versatile XRF scanner presented here has been designed and built at the C2RMF in response to specific constraints: transportability, cost-effectiveness and ability to scan large areas within a single working day. The instrument is based on a standard X-ray generator with submillimetre collimated beam and a SDD-based spectrometer to collected X-ray spectra. The instrument head is scanned in front of the painting by means of motorised movements to cover an area up to 300 9 300 mm 2 with a resolution of 0.5 mm (600 9 600 pixels). The 15-kg head is mounted on a stable photo stand for rapid positioning on paintworks and maintains a free side-access for safety; it can also be attached to a lighter tripod for field measurements. Alignment is achieved with a laser pointer and a micro-camera. With a scanning speed of 5 mm/s and 0.1 s/point, elemental maps are collected in 10 h, i.e. a working day. The X-ray spectra of all pixels are rapidly processed using an open source program to derive elemental maps. To illustrate the capabilities of this instrument, this contribution presents the results obtained on the Belle Ferronnière painted by Leonardo da Vinci (1452-1519) and conserved in the Musée du Louvre, prior to its restoration at the C2RMF.

Discovering the material palette of the artist: a p‐XRF stratigraphic study of the Giotto panel ‘God the Father with Angels’

“…Beyond its own history, a work of art as a painting or a fresco can reveal details regarding its historical age such as the habits or the tastes of people, and, more important for scientists and art historians, information regarding the technique, and the creative process used by the painter. Discovering how painted works of art were realized or, eventually modified, can be done by gathering data about its structure and composition and, because a great deal of information can lie tens or hundreds of microns below the surface, the possibility of study artworks layer by layer is valuable for art research In this scenario, X‐ray fluorescence (XRF) results as the most diffused and powerful technique; it gives extremely useful results, also as a consequence of the development of new devices, more and more sensitive and reliable, mainly when coupled with other spectroscopic techniques . Thanks to the fact that XRF allows a non‐destructive and non‐invasive elemental analysis also in air, XRF makes the study of the stratigraphic distribution of elements feasible also for cultural heritage objects: samples that require damage avoiding as a key feature to perform experimental studies.…”

Non-Invasive and Non-Destructive Examination of Artistic Pigments, Paints, and Paintings by Means of X-Ray Methods

“…With these MA-XRF scanners, it was possible to examine a great variety of artworks by well-known artists such as Rubens [22], Rembrandt [151][152][153], Vermeer [154], Goya [155], Van Gogh [145,156], Magritte [157], Martins [158] and Pollock [159], and to discover new information on their artistic history and on their current state of conservation. Several X-ray instrumentation manufacturers and research institutions have recently described MA-XRF scanners of their own making [27,160].…”

Integrated X-ray fluorescence and diffuse visible-to-near-infrared reflectance scanner for standoff elemental and molecular spectroscopic imaging of paints and works on paper

“…Since the original development of the Gallery's XRF scanner, a variety of noncommercial, XRF scanners for cultural heritage science have been developed based on laboratory X-ray sources. Ravaud et al [10] have developed a highly portable XRF scanner without sacrificing performance. More advanced scanners, such as one developed by Romano et al [11], which provide high scan rates with confocal X-ray optics, and on-the-fly fitting of the XRF spectra have been constructed.…”