Tracking the transformation and transport of arsenic sulfide pigments in paints: synchrotron-based X-ray micro-analyses

Keune, Katrien; Mass, Jennifer L.; Meirer, Florian; Pottasch, Carol; Loon, Annelies van; Hull, Alyssa M.; Church, J.P.; Pouyet, Émeline; Cotte, Marine; Mehta, Apurva

doi:10.1039/c4ja00424h

Cited by 81 publications

(79 citation statements)

References 27 publications

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“…They are isotropic and X-ray-amorphous, which corresponds with the Raman results from the previous section ("p-XRD and p-Raman spot analyses") and explains why portable XRD did not pick up a diffraction pattern [24]. The particles are not a degradation product of the natural form [25]. In fact, this artificial form of orpiment is more stable than the natural product, which is very vulnerable to degradation when exposed to light [18].…”

Section: Cross-section Analysessupporting

confidence: 66%

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: Cross-section Analysessupporting

confidence: 66%

Artificial orpiment, a new pigment in Rembrandt’s palette

et al. 2017

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“…The fact that the arsenate is found at the interface between layers 2 and 3 and not in relatively high concentrations throughout layer 2 indicates that the arsenic is 'trapped' in the upper part of paint layer 2. A similar observation was made in a degraded orpiment/realgar paint sample taken from Still Life with Five Apricots by Adriaen Coorte discussed by Keune et al 2015 [5]. In general, as arsenates are also predominantly present in layer 6, we can conclude that arsenic is also accumulated in lead rich areas.…”

Section: Chemical Speciation and Localization Of Arsenic In Degraded supporting

confidence: 52%

“…5q) (for reference spectra see ref. [5]). A weak band at 790 cm −1 was observed in the sum of many spectra taken from layers 1 and 5.…”

Section: Chemical Speciation and Localization Of Arsenic In Degraded mentioning

confidence: 99%

“…Re-varnishing the affected regions of the work, unfortunately, does not mitigate the problem because the highly mobile degradation products migrate through the varnish. The previous study indicated that the photo-degradation products of orpiment and realgar are highly water soluble, and consequently they do not remain at the location of the original pigment in the paint, but migrate throughout the whole multi-layered paint system [5]. For example, the investigation of an early eighteenth-century chest on stand that had been repeatedly varnished after the application of an orpiment design showed that the photo-oxidized arsenic species had migrated through each varnish layer, with larger deposits visible at the interface of each pair of layers [5].…”

Section: Introductionmentioning

confidence: 99%

“…Recent synchrotron radiationbased arsenic (As) K-edge micro X-ray absorption near edge structure (μ-XANES) studies following preliminary µFTIR studies revealed another set of degradation products, i.e. arsenate compounds (As 5+ ) present as calcium, lead, aluminum and iron arsenates depending on the pigments and fillers surrounding the original arsenic sulfide pigments [5]. The arsenates (As 5+ ) are the phases that spread throughout the entire multi-layered paint system and dominate the photo-degraded paint, ground, and varnish layers, while the arsenite compounds (As 3+ ) seem to be located close to the intact arsenic sulfide pigment.…”

Section: Introductionmentioning

confidence: 99%

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Analytical imaging studies of the migration of degraded orpiment, realgar, and emerald green pigments in historic paintings and related conservation issues

et al. 2016

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Yellow orpiment (As 2 S 3 ) and red-orange realgar (As 4 S 4 ) photo-degrade and the nineteenth-century pigment emerald green (Cu(C 2 H 3 O 2 ) 2 ·3Cu(AsO 2 ) 2 ) degrades into arsenic oxides. Because of their solubility in water, arsenic oxides readily migrate and are found throughout the multi-layered paint system. The widespread arsenic migration has consequences for conservation, and this paper provides better insight into the extent of the problem. Five paint samples containing orpiment, realgar or emerald green pigments deriving from paintings by De Heem (17th C), Van Gogh (19th C), Rousseau (19th C), an unknown 17th C northern European artist and an Austrian painted cupboard (19th C) were investigated using SEM/EDX, imaging ATR-FTIR and arsenic (As) K-edge μ-XANES to obtain the spatial distribution and chemical speciation of arsenic in the paint system. In all of the samples investigated arsenic had migrated throughout the multi-layered paint structure of the art object, from support to varnish. Furthermore, As 5+ -species were found throughout the entire paint sample. We hypothesize that arsenic trioxide is first formed, dissolves in water, further oxidizes to arsenic pentaoxide, and then reacts with lead, calcium and other ions and is deposited in the paint system as insoluble arsenates. Since the degradation of arsenic pigments such as orpiment, realgar and emerald green occurs through a highly mobile intermediate stage, it not only affects the regions rich in arsenic pigments, but also the entire object, including substrate and top varnish layers. Because of this widespread potential for damage, preventing degradation of arsenic pigments should be prioritized and conservators should minimize exposure of objects containing arsenic pigments to strong light, large fluctuations in relative humidity and water-based cleaning agents.

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Low concentrations of sodium arsenite induce hepatotoxicity in prepubertal male rats

Samelo

Medeiros

Cavalcante

et al. 2019

Environmental Toxicology

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Arsenic (As) can contaminate air, soil, water, and organisms through mobilization of natural mineralogical deposits or anthropogenic actions. Inorganic‐As compounds are more toxic and widely available in aquatic environments, including drinking water reservoir catchments. Since little is known about its effects on prepubertal mammals, the present study focused on it. Hence, As was administered through drinking water to male Wistar rats from postnatal day 23 to 53. Negative control group received vehicle only (filtered water); As 1 group received AsNaO2 at 0.01 mg L−1 and As2 group received AsNaO2 at 10 mg L−1. It was investigated hepatic and renal toxicity of AsNaO2 (ie, histopathology and apoptosis analysis), as well as its mutagenicity (ie, micronucleus test in liver and bone marrow), cytotoxicity (ie, frequency and type of erythrocytes in blood), and genotoxicity (ie, comet assay in blood). Also, As determination was performed in hepatic and renal tissues. Data obtained revealed that immature organisms present a pattern of arsenic accumulation similar to that observed in adults, suggesting similarity in metabolic processes. In addition, liver showed to be an important target tissue for As toxicity in these experimental conditions, exhibiting infiltrate of defense cells, DNA damages, and increased apoptosis rates.

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Tracking the transformation and transport of arsenic sulfide pigments in paints: synchrotron-based X-ray micro-analyses

Abstract: Realgar and orpiment, arsenic sulfide pigments used in historic paints, degrade under the influence of light, resulting in transparent, whitish, friable and/or crumbling paints.

Cited by 81 publications

References 27 publications

Artificial orpiment, a new pigment in Rembrandt’s palette

Artificial orpiment, a new pigment in Rembrandt’s palette

Analytical imaging studies of the migration of degraded orpiment, realgar, and emerald green pigments in historic paintings and related conservation issues

Low concentrations of sodium arsenite induce hepatotoxicity in prepubertal male rats

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