Optimization of mobile scanning macro-XRF systems for the in situ investigation of historical paintings

Alfeld, Matthias; Janssens, Koen; Dik, Joris; Nolf, Wout De; Snickt, Geert Van der

doi:10.1039/c0ja00257g

Cited by 163 publications

(122 citation statements)

References 16 publications

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“…During the re-installation of the Rijksmuseum in 2013, the opportunity was taken to scan the picture using a mobile MA-XRF scanner. This is a recent chemical imaging tool that reveals the elemental distributions on and below the paint surface in a non-invasive manner [12]. Notably, the resulting arsenic (As) map revealed areas of high-intensity in Isaac's sleeve and Rebecca's dress where it could be established that it was not related with the pigment smalt that also contains arsenic.…”

Section: Introductionmentioning

confidence: 99%

Artificial orpiment, a new pigment in Rembrandt’s palette

et al. 2017

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This paper reports on how the application of macro X-ray fluorescence (MA-XRF) imaging, in combination with the re-examination of existing paint cross-sections, has led to the discovery of a new pigment in Rembrandt's palette: artificial orpiment. In the NWO Science4Arts 'ReVisRembrandt' project, novel chemical imaging techniques are being developed and applied to the study of Rembrandt's late paintings in order to help resolve outstanding questions and to gain a better understanding of his late enigmatic painting technique. One of the selected case studies is the Portrait of a Couple as Isaac and Rebecca, known as 'The Jewish Bride' , dated c. 1665 and on view in the Rijksmuseum. During the re-installation of the Rijksmuseum in 2013, the picture was scanned using the Bruker M6 Jetstream MA-XRF scanner. The resulting elemental distribution maps made it possible to distinguish many features in the painting, such as bone black remains of the original hat (P, Ca maps), and the now discolored smalt-rich background (Co, Ni, As, K maps). The arsenic (As) map also revealed areas of high-intensity in Isaac's sleeve and Rebecca's dress where it could be established that it was not related with the pigment smalt that also contains arsenic. This pointed to the presence of a yellow or orange arsenic-containing pigment, such as realgar or orpiment that is not associated with the artist's palette. Subsequent examination of existing paint cross-sections from these locations taken by Karin Groen in the 1990s identified isolated, almost perfectly round particles of arsenic sulfide. The round shape corresponds with published findings on a purified form of artificial orpiment glass obtained by dry processing, a sublimation reaction. In bright field, the particles characteristically exhibit a dark cross in the middle caused by internal light reflections. The results of additional non-invasive techniques (portable XRD and portable Raman) are discussed, as well as the implications of this finding and how it fits with Rembrandt's late experimental painting technique.

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Section: Introductionmentioning

confidence: 99%

Artificial orpiment, a new pigment in Rembrandt’s palette

et al. 2017

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“…Briefly, a self-built macro-XRF scanner, utilizing a 50 W molybdenum X-ray tube, operated at 50 kV and 1 mA, with a fixed polycapillary lens and four energy dispersive X-ray detectors, was used to scan the painting at a step size of 1 mm and an integration time of 0.2 s per pixel with up to 1.9 s per pixel for areas of enhanced interest [30]. The resulting XRF image cubes were processed by Datamuncher software [31], PyMCA [32] and other in-house written software to produce elemental distribution maps of peak area.…”

Section: X-ray Fluorescence Imaging Spectroscopy Macroscopic Xrf or mentioning

confidence: 99%

Separating two painting campaigns in Saul and David, attributed to Rembrandt, using macroscale reflectance and XRF imaging spectroscopies and microscale paint analysis

et al. 2018

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Late paintings of Rembrandt van Rijn (1606-1669) offer intriguing problems for both art historians and conservation scientists. In the research presented here, the key question addressed is whether observed stylistic differences in paint handling can be correlated with material differences. In Saul and David, in the collection of the Royal Picture Gallery Mauritshuis in The Hague, NL, the stylistic differences between the loose brushwork of Saul's cloak and the more detailed depiction of his turban and the figure of David have been associated with at least two painting stages since the late 1960s, but the attribution of each stage has been debated in the art historical literature. Stylistic evaluation of the paint handling in the two stages, based on magnified surface examination, is further described here. One of the research goals was to determine whether the stylistic differences could be further differentiated with macroscale and microscale methods of material analysis. To address this, selected areas of the painting having pronounced stylistic differences were investigated with two macroscopic chemical imaging methods, X-ray fluorescence and reflectance imaging spectroscopies. The pigments used were identified and their spatial distribution was mapped. The mapping results show that the passages rendered in more detail and associated stylistically with the first painting stage, such as the orange-red color of David's garment or the Greek key design in Saul's turban, were painted with predominately red ochre mixed with vermilion. The regions of loose, bold brushwork, such as the orange-red slashing strokes in the interior of Saul's cloak, associated with the second painting stage, were painted with predominately red ochre without vermilion. These macroscale imaging results were confirmed and extended with scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) analysis of three cross-sections taken from regions of stylistic differences associated with the two painting stages, including one sample each from the right and left sleeve of David, and one from the interior of Saul's cloak. SEM-EDX also identified a trace component, barium sulfate, associated with the red ochre of the second stage revisions. Combining mapping information from two spectroscopic imaging methods with localized information from microscopic samples has clearly shown that the stylistic differences observed in the paint handling are affiliated with differences in the chemical composition of the paints.

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“…In contrast, XRF imaging spectroscopy has been implemented using a raster scanning method, which provides detailed information about the elements used and in some cases the way they are layered within a work of art. These XRF scans can take many tens of hours to complete depending on the size of the painting [19].…”

Section: Introductionmentioning

confidence: 99%

Visible and infrared imaging spectroscopy of paintings and improved reflectography

et al. 2016

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Background: Imaging spectroscopy, the collection of spatially co-registered images in many contiguous spectral bands, has been developed for remote sensing of the Earth utilizing reflectance or luminescence. In this paper we summarize findings on the application of imaging spectroscopy to works of art in order to identify and map artists' pigments, improve the visualization of preparatory sketches, and identify non-original material.Methods: Two types of novel hyperspectral cameras, one operating from the visible to near-infrared (VNIR, 400-900 nm) and the other in the shortwave infrared (SWIR, 950-1700 nm), have been used to collect diffuse reflectance spectral image cubes from a variety of paintings. The resulting cubes (400-1700 nm, 310 spectral bands) were calibrated to reflectance and the resulting spectra compared with point-based spectra collected with a fiber reflectance spectrometer (350-2500 nm). In addition, a calibrated multispectral camera (600-950 nm, eight spectral bands) was used to obtain luminescence spectral image cubes after exciting paintings at blue wavelengths.Results: False-color images obtained from the SWIR imaging system are shown to give improved visualization of changes from paintings having large and complex reworkings, e.g. Pablo Picasso's The Tragedy (1903). False-color images and reflectance spectra allowed definitive identification of restoration in a late 13th century Sienese painting that cannot be seen by traditional infrared reflectography. Spectral image processing on the reflectance image cubes have been used to identify the primary pigments or pigment mixtures. For example, the primary pigments and their distribution in Picasso's Peonies (1901) was determined and compared with x-ray fluorescence (XRF) analysis and scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS). Conclusion:The results show that the combination of both the SWIR reflectance data and the luminescence data provides a more robust ability to assign the pigments than with visible spectroscopy alone. Also highlighted is the utility of reflectance imaging spectroscopy in the SWIR region to better reveal specific paint changes, including changes in the drawings and markings made by the original artist, or changes made by a subsequent conservator such as a fill.

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Optimization of mobile scanning macro-XRF systems for the in situ investigation of historical paintings

Cited by 163 publications

References 16 publications

Artificial orpiment, a new pigment in Rembrandt’s palette

Artificial orpiment, a new pigment in Rembrandt’s palette

Separating two painting campaigns in Saul and David, attributed to Rembrandt, using macroscale reflectance and XRF imaging spectroscopies and microscale paint analysis

Visible and infrared imaging spectroscopy of paintings and improved reflectography

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