Macroscopic X-ray Powder Diffraction Scanning, a New Method for Highly Selective Chemical Imaging of Works of Art: Instrument Optimization

Vanmeert, Frederik; Nolf, Wout De; Meyer, Steven De; Dik, Joris; Janssens, Koen

doi:10.1021/acs.analchem.8b00240

Cited by 36 publications

(29 citation statements)

References 47 publications

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“…In a second phase, MA-XRPD imaging experiments were carried out on a small area-see rectangle in Fig. 1-using a mobile MA-XRF/XRPD scanning instrument that was operated in reflection mode [11,19,20]. Within this area, in order to study the in-depth distribution of primary and secondary compounds, a paint sample was taken.…”

Section: Methodsmentioning

confidence: 99%

“…For the reflection mode MA-XRF/XRPD measurements, a self-built system [11,19,20] consisting of a low power X-ray micro source (50W, IμS-Cu, Incoatec GmbH, Germany) was employed, delivering a monochromatic (Cu-K α ; 8.04 keV) and focused X-ray beam with a photon flux of 2.9 × 10 8 photon s −1 (focal spot diameter: ca. 140 μm; output focal distance: ca.…”

Section: Combined Ma-xrf/xrpd Mappingmentioning

confidence: 99%

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Combined Micro- and Macro scale X-ray powder diffraction mapping of degraded Orpiment paint in a 17th century still life painting by Martinus Nellius

et al. 2019

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The spontaneous chemical alteration of artists' pigment materials may be caused by several degradation processes. Some of these are well known while others are still in need of more detailed investigation and documentation. These changes often become apparent as color modifications, either caused by a change in the oxidation state in the original material or the formation of degradation products or salts, via simple or more complex, multistep reactions. Arsenic-based pigments such as orpiment (As 2 S 3) or realgar (α-As 4 S 4) are prone to such alterations and are often described as easily oxidizing upon exposure to light. Macroscopic X-ray powder diffraction (MA-XRPD) imaging on a sub area of a still life painting by the 17th century Dutch painter Martinus Nellius was employed in combination with microscopic (μ-) XRPD imaging of a paint cross section taken in the area imaged by MA-XRPD. In this way, the in situ formation of secondary metal arsenate and sulfate species and their migration through the paint layer stack they originate from could be visualized. In the areas originally painted with orpiment, it could be shown that several secondary minerals such as schultenite (PbHAsO 4), mimetite (Pb 5 (AsO 4) 3 Cl), palmierite (K 2 Pb(SO 4) 2) and syngenite (K 2 Ca(SO 4) 2 •H 2 O) have formed. Closer inspection of the cross-sectioned paint layer stack with μ-XRPD illustrates that the arsenate minerals schultenite and mimetite have precipitated at the interface between the orpiment layer and the layer below that is rich in lead white, i.e. close to the depth of formation of the arsenate ions. The sulfate palmierite has mostly precipitated at the surface and upper layers of the painting.

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Section: Methodsmentioning

confidence: 99%

Section: Combined Ma-xrf/xrpd Mappingmentioning

confidence: 99%

Combined Micro- and Macro scale X-ray powder diffraction mapping of degraded Orpiment paint in a 17th century still life painting by Martinus Nellius

et al. 2019

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“…In recent years, macroscopic X-ray powder diffraction (MA-XRPD) has also been successfully converted from a synchrotron-based imaging technique on the microscopic scale to a non-invasive laboratory-based technique on the macroscopic scale that can be deployed in situ in transmission mode, providing information on the bulk composition of the paint stratigraphy [16]. MA-XRPD was successfully employed in transmission mode to visualise the different types of chrome yellow used in Van Gogh's Sunflowers (1889, Van Gogh Museum) and to provide information about the orientation of the needleshaped crystals in his brushstrokes [17].…”

Section: Introductionmentioning

confidence: 99%

Imaging secondary reaction products at the surface of Vermeer’s Girl with the Pearl Earring by means of macroscopic X-ray powder diffraction scanning

et al. 2019

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The use of non-invasive macroscopic imaging techniques is becoming more prevalent in the field of cultural heritage, especially to avoid invasive procedures that damage valuable artworks. For this purpose, an X-ray powder diffraction scanner (MA-XRPD) capable of visualising crystalline compounds in a highly specific manner was recently developed. Many inorganic pigments present in paintings fall into this category of materials. In this study, the 17th century oil painting Girl with a Pearl Earring (c. 1665) by Johannes Vermeer was analysed with a combination of transmission and reflection mode MA-XRPD. By employing this scanner in reflection mode, the relative sensitivity for compounds that are present at the paint surface could be increased, establishing it as a highly relevant technique for investigating the degradation processes that are ongoing at paint surfaces. Many of the original pigments employed by Vermeer could be identified, along with four secondary alteration products: gypsum (CaSO 4 ·2H 2 O), anglesite (PbSO 4 ), palmierite (K 2 Pb(SO 4 ) 2 ) and weddellite (CaC 2 O 4 ·2H 2 O). The formation of gypsum was linked to the presence of chalk in the upper glaze layer while the formation of palmierite and weddellite is driven by the presence of lake pigments (and their substrates). In this manner, MA-XRPD can also be used to pinpoint locations relevant for sampling and synchrotron µ-XRPD analysis, which provides information on the microscopic make-up of the paint. A paint cross-section taken from an area rich in palmierite was analysed with synchrotron µ-XRPD, which confirmed the presence of this secondary compound at the interface of the upper paint layer with the ground layer as well as the presence of anglesite in the ground layer. The capacity of MA-XRPD to identify and chart secondary alteration products in a non-invasive manner has only very recently been demonstrated and makes it a highly relevant technique for the assessment of the chemical condition of works of art.

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“…Many XRD mapping experiments (in particular those performed on paintings and manuscripts) aim at identifying the composition of the various pigments used by the artists . The pioneering application of XRD mapping was on a fragment of a Roman wall painting, displaying a portrait.…”

Section: Applicationsmentioning

confidence: 99%

“…15 minutes) precluded their application for 2D mapping. More recently, instrumental developments based on state‐of‐the‐art focusing optics and area detectors with a fast read‐out time allowed to deploy XRD mapping inside the laboratory . In this case, the monochromatic X‐ray beam is formed using Montel optics coated with laterally graded multilayers.…”

Section: Instrumentationmentioning

confidence: 99%

X‐ray Diffraction Mapping for Cultural Heritage Science: a Review of Experimental Configurations and Applications

González

Cotte

Vanmeert

et al. 2019

Chemistry A European J

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X-ray diffraction (XRD) mapping consists in the acquisition of XRD patterns at each pixel (or voxel) of an area (or volume). The spatial resolution ranges from the micrometer (mXRD) to the millimeter (MA-XRD)s cale, making the technique relevant for tiny samples up to large objects. Although XRD is primarily used for the identification of different materials in (complex) mixtures, additional information regarding the crystallite size, their orientation, and their indepth distribution can also be obtained. Through mapping, these different types of information can be located on the studied sample/object. Cultural heritage objects are usually highly heterogeneous, and contain both original and later (degradation, conservation) materials. Their structural characterization is required both to determine ancient manufacturing processes and to evaluate their conservation state. Togetherw ith other mapping techniques, XRD mapping is increasingly used for these purposes. Here, the authors review applicationsa sw ell as the various configurations for XRD mapping (synchrotron/laboratory X-ray source, poly-/monochromatic beam,micro/macro beam, 2D/3D, transmission/reflectionm ode). On-going hardware and software developments will further establish the technique as ak ey tool in heritage science.[a] Dr.

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Macroscopic X-ray Powder Diffraction Scanning, a New Method for Highly Selective Chemical Imaging of Works of Art: Instrument Optimization

Cited by 36 publications

References 47 publications

Combined Micro- and Macro scale X-ray powder diffraction mapping of degraded Orpiment paint in a 17th century still life painting by Martinus Nellius

Combined Micro- and Macro scale X-ray powder diffraction mapping of degraded Orpiment paint in a 17th century still life painting by Martinus Nellius

Imaging secondary reaction products at the surface of Vermeer’s Girl with the Pearl Earring by means of macroscopic X-ray powder diffraction scanning

X‐ray Diffraction Mapping for Cultural Heritage Science: a Review of Experimental Configurations and Applications

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