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“Revealing the distribution of metal carboxylates in oil paint from the micro- to nanoscale”. Ma X, Beltran V, Ramer G, Pavlidis G, Parkinson DY, Thoury M, Meldrum T, Centrone A, Berrie BH, Angewandte Chemie: international edition in English 58, 11652 (2019). http://doi.org/10.1002/ANIE.201903553
Abstract: Oil paints comprise pigments, drying oils, and additives that together confer desirable properties, but can react to form metal carboxylates (soaps) that may damage artworks over time. To obtain information on soap formation and aggregation, we introduce a new tapping-mode measurement paradigm for the photothermal induced resonance (PTIR) technique that enables nanoscale IR spectroscopy and imaging on highly heterogenous and rough paint thin sections. PTIR is used in combination with mu-computed tomography and IR microscopy to determine the distribution of metal carboxylates in a 23-year old oil paint of known formulation. Results show that heterogeneous agglomerates of Al-stearate and a Zn-carboxylate complex with Zn-stearate nano-aggregates in proximity are distributed randomly in the paint. The gradients of zinc carboxylates are unrelated to the Al-stearate distribution. These measurements open a new chemically sensitive nanoscale observation window on the distribution of metal soaps that can bring insights for understanding soap formation in oil paint.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/ANIE.201903553
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“Effects of IR heating on distribution and transport of gaseous air pollutants in urban and mountain churches in Poland”. Bencs L, Spolnik Z, Worobiec A, Samek L, Jutte BAHG, Van Grieken R, Journal of cultural heritage 36, 200 (2019). http://doi.org/10.1016/J.CULHER.2018.09.007
Abstract: The spatial distribution and temporal concentration variation of a set of gaseous air components (e.g., CO2, CO, H2CO, H2O) have been monitored with a multi-channel photoacoustic gas-analyzer in an urban church ( Saint Catherine's, Cracow) and a mountain church ( Saint Michaels Archangel, Szalowa) of Poland, in order to assess the likely effects of air pollution indoors under the influence of provisory electrical infrared (IR) heaters and without heating. Likewise, the ventilation characteristic and the leakage of these buildings with different constructions (i.e., plastered stone and wooden structures) with the assistance of decay curves of SF6 tracer gas was evaluated and compared. The wooden building in Szalowa, due to its more open structure, developed about one order higher ventilation rates (e.g., 0.9-1.3 h(-1)) than the stone church in Cracow (e.g., 0.1 h(-1)). The IR-heating affected only modestly the ventilation rate of the wooden church (e.g., 1.2-1.6 h(-1)), but it increased significantly that of the plastered stone church (e.g., 0.27 h(-1)). The ventilation rates were also assessed with the use of the CO2 curve decay method, and satisfactory agreement was found with those observed by the use of SF6 tracer. The spatial distribution of the studied gaseous pollutants (CO2, H2O) was found to be in some occasions nonhomogeneous in both buildings, due to the active usage of the IR-heating, especially, during a couple of consecutive liturgical services. Besides the pollution events due to ingress of gaseous air pollutants, present at enhanced levels outdoors, increased CO, CO2 and H2CO peaks were observed indoors too, which, in most cases, could be associated with incense burning. (C) 2018 Elsevier Masson SAS. All rights reserved.
Keywords: A1 Journal article; Art; History; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Laboratory Experimental Medicine and Pediatrics (LEMP)
DOI: 10.1016/J.CULHER.2018.09.007
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“MA-XRF imaging as a tool to characterize the 16th century heraldic stained-glass panels in Ghent Saint Bavo Cathedral”. Legrand S, van der Snickt G, Cagno S, Caen J, Janssens K, Journal of cultural heritage 40, 163 (2019). http://doi.org/10.1016/J.CULHER.2019.06.003
Abstract: MA-XRF is a novel macroscopic imaging technique originally developed for easel paintings and recently made available to glass conservators. This paper discusses the first real-life contribution of MA-XRF imaging to a conservation intervention of stained-glass panels. The six panels under study belong to the cathedral building since their creation in 1555-1559 AD. MA-XRF appeared an outstanding tool for first-line screening of stained-glass windows, providing readily interpretable information on glass type, coloring and alteration processes. In particular, the chemical imaging technique allowed distinguishing unambiguously the surviving original glass panes from later additions, thereby ensuring a correct historical understanding. From a more practical point of view, the experiments supplied accurate schemes that can be directly incorporated in condition reports and assist designing the ensuing conservation approach. (C0 2019 Elsevier Masson SAS. All rights reserved.
Keywords: A1 Journal article; Art; History; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
DOI: 10.1016/J.CULHER.2019.06.003
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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”. Simoen J, De Meyer S, Vanmeert F, De Keyser N, Avranovich E, van der Snickt G, Van Loon A, Keune K, Janssens K, Heritage science 7, 83 (2019). http://doi.org/10.1186/S40494-019-0324-4
Abstract: 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 (As2S3) or realgar (alpha-As4S4) 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 (mu-) 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 (PbHAsO4), mimetite (Pb-5(AsO4)(3)Cl), palmierite (K2Pb(SO4)(2)) and syngenite (K2Ca(SO4)(2)center dot H2O) have formed. Closer inspection of the cross-sectioned paint layer stack with mu-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.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
Times cited: 2
DOI: 10.1186/S40494-019-0324-4
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“Imaging secondary reaction products at the surface of Vermeer's Girl with the Pearl Earring by means of macroscopic X-ray powder diffraction scanning”. De Meyer S, Vanmeert F, Vertongen R, van Loon A, Gonzalez V, van der Snickt G, Vandivere A, Janssens K, Heritage science 7, 67 (2019). http://doi.org/10.1186/S40494-019-0309-3
Abstract: 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 (CaSO4 center dot 2H(2)O), anglesite (PbSO4), palmierite (K2Pb(SO4)(2)) and weddellite (CaC2O4 center dot 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 mu-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 mu-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.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
Times cited: 5
DOI: 10.1186/S40494-019-0309-3
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“Rembrandt's An Old Man in Military Costume : combining hyperspectral and MA-XRF imaging to understand how two paintings were painted on a single panel”. MacLennan D, Trentelman K, Szafran Y, Woollett AT, Delaney JK, Janssens K, Dik J, Journal of the American Institute for Conservation 58, 54 (2019). http://doi.org/10.1080/01971360.2018.1540245
Abstract: Over the past several decades the painting An Old Man in Military Costume by Rembrandt Harmensz van Rijn (ca. 1630-31; J. Paul Getty Museum, 78.PB.246) has been the subject of a number of investigations carried out in order to better visualize a second painting beneath the surface figure. The underlying image – the head and shoulders of a man wearing a cloak – is oriented 180 degrees from the upper image and appears to be fairly complete. Scanning macro x-ray fluorescence (XRF) spectroscopy reveals the face is painted with lead white and a mercury-containing pigment (likely vermilion), and the cloak is painted with a copper-containing pigment. Following the revelation and digital color reconstruction of the underlying figure, a number of questions still remained. Here, through the use of infrared reflectance imaging spectroscopy (i.e., hyperspectral imaging) and macro-XRF imaging spectroscopy, together with cross-sections taken from targeted areas, the sequence of painting in both compositions was explored. Of particular interest was the discovery of evidence of multiple attempts to situate the lower figure, and the subsequent application of a blocking-out layer over the lower figure before the artist rotated the panel and executed the upper figure. In addition, examination of the placement of the two images on the panel adds to our understanding of the subtle complexities of Rembrandt's working process. RESUMEAu cours des dernieres decennies, la peinture Le vieil homme en costume militaire de Rembrandt Harmensz van Rijn (ca. 1630-31; J. Paul Getty Museum, 78.PB.246) a fait l'objet de nombreuses investigations menees dans le but de mieux visualiser une seconde peinture dissimulee sous la surface. L'image sous-jacente – la tete et les epaules d'un homme vetu d'une cape – est orientee a 180 degres de de l'image du vieil homme, et elle semble assez complete. La spectroscopie a macro-balayage de fluorescence X (MA-XRF) revele que le visage est peint avec du blanc de plomb et un pigment contenant du mercure (comme le vermillon), et que la cape est peinte avec un pigment a base de cuivre. Plusieurs questions restaient en suspens suite a cette decouverte et a la reconstruction numerique en couleur de l'image sous-jacente. Grace a l'emploi de techniques d'imagerie comme la spectroscopie proche infrarouge (ex., imagerie hyperspectrale) et l'imagerie MA-XRF, combinees a l'analyse de coupes stratigraphiques prelevees a des endroits cibles, on a pu explorer la sequence d'application des couches picturales de chacune des deux compositions. Une decouverte particulierement interessante est la preuve que l'artiste a fait plusieurs tentatives pour positionner la figure sous-jacente puis, a ensuite applique une couche pour la recouvrir completement avant de faire pivoter le panneau et peindre la figure du vieil homme. De plus, l'examen du positionnement des deux images sur le panneau ajoute a notre comprehension de la subtile complexite du processus de creation de Rembrandt. Traduit par Elisabeth Forest. RESUMONas ultimas decadas, a pintura Um Velho em Traje Militar, de Rembrandt Harmensz van Rijn (ca. 1630-31; J. Paul Getty Museum, 78.PB.246), foi objeto de uma serie de investigacoes realizadas para visualizar melhor uma segunda pintura abaixo da figura aparente. A imagem subjacente – a cabeca e os ombros de um homem usando uma capa – e orientada a 180 graus da imagem superior e parece estar bastante completa. O macro mapeamento de imagem por espectroscopia de fluorescencia de raios X (FRX) revela que a face e pintada com branco de chumbo e um pigmento contendo mercurio (provavelmente vermelhAo), e a capa e pintada com um pigmento contendo cobre. Apos a descoberta e reconstrucAo digital da cor da figura subjacente, uma serie de questoes ainda permanecem. EntAo, atraves da utilizacAo do mapeamento por imagem de espectroscopia de refletancia por infravermelhos (i.e. mapeamento hiperespectral) e macro mapeamento por imagem de FRX, juntamente com cortes estratigraficos de amostras retiradas de areas de interesse, a pintura em ambas as composicoes foi explorada. De particular interesse foi a descoberta de evidencias de multiplas tentativas de posicionar a figura subjacente, e a subsequente aplicacAo de uma camada intermediaria de separacAo sobre a figura inferior antes do artista girar o painel e executar a figura superior. Alem disso, o exame da colocacAo das duas imagens no painel aumenta nossa compreensAo das sutis complexidades do processo de trabalho de Rembrandt. Traduzido por Marcia Rozzi e Beatriz Haspo. RESUMENA lo largo de las ultimas decadas, la pintura Un anciano con traje militar de Rembrandt Harmensz van Rijn (ca. 1630-31; J. Paul Getty Museum, 78.PB.246) ha sido objeto de varias investigaciones realizadas con el fin de visualizar mejor una segunda pintura debajo de la figura de la superficie. La imagen subyacente, la cabeza y los hombros de un hombre que lleva una capa, esta orientada a 180 grados de la imagen superior y parece estar bastante completa. La espectroscopia de fluorescencia de rayos X (XRF) de barrido revela que la cara esta pintada con blanco de plomo y un pigmento que contiene mercurio (probablemente bermellon), y la capa esta pintada con un pigmento que contiene cobre. Tras la revelacion y la reconstruccion digital del color de la figura subyacente, aun quedaban algunas preguntas. Aqui, por medio del uso de la espectroscopia de imagenes de reflectancia infrarroja (es decir, imagenes hiperespectrales) e imagenes macro-XRF, junto con las secciones transversales tomadas de areas especificas, se exploro la secuencia de pintura en ambas composiciones. De particular interes fue el descubrimiento de evidencia de multiples intentos de situar la figura inferior, y la aplicacion posterior de una capa de bloqueo sobre la figura inferior antes de que el artista rotara el panel y ejecutara la figura superior. Ademas, el examen de la colocacion de las dos imagenes en el panel contribuye a nuestra comprension de las sutiles complejidades del proceso de trabajo de Rembrandt. Traduccion: Amparo Rueda.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Times cited: 2
DOI: 10.1080/01971360.2018.1540245
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“Beauty is skin deep : the skin tones of Vermeer's Girl with a Pearl Earring”. van Loon A, Vandivere A, Delaney JK, Dooley KA, De Meyer S, Vanmeert F, Gonzalez V, Janssens K, Leonhardt E, Haswell R, de Groot S, D'Imporzano P, Davies GR, Heritage science 7, 102 (2019). http://doi.org/10.1186/S40494-019-0344-0
Abstract: The soft modelling of the skin tones in Vermeer's Girl with a Pearl Earring (Mauritshuis) has been remarked upon by art historians, and is their main argument to date this painting to c. 1665. This paper describes the materials and techniques Vermeer used to accomplish the smooth flesh tones and facial features of the Girl, which were investigated as part of the 2018 Girl in the Spotlight research project. It combines macroscopic X-ray fluorescence imaging (MA-XRF), reflectance imaging spectroscopy (RIS), and 3D digital microscopy. Vermeer built up the face, beginning with distinct areas of light and dark. He then smoothly blended the final layers to create almost seamless transitions. The combination of advanced imaging techniques highlighted that Vermeer built the soft contour around her face by leaving a 'gap' between the background and the skin. It also revealed details that were otherwise not visible with the naked eye, such as the eyelashes. Macroscopic imaging was complemented by the study of paint cross-sections using: light microscopy, SEM-EDX, FIB-STEM, synchrotron radiation mu-XRPD and FTIR-ATR. Vermeer intentionally used different qualities or grades of lead white in the flesh paints, showing different hydrocerussite/cerussite ratios and particle sizes. Lead isotope analysis showed that the geographic source of lead, from which the different types of lead white were manufactured, was the same: the region of Peak District of Derbyshire, UK. Finally, cross-section analysis identified the formation of new lead species in the paints: lead soaps and palmierite (K2Pb(SO4)(2)), associated with the red lake.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1186/S40494-019-0344-0
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“Supplementing the eye : the technical analysis of Frans Hals's paintings –, ii”. Tummers A, Wallert A, De Keyser N, The Burlington magazine 161, 996 (2019)
Abstract: The painting 'Two fisherboys' has long caused confusion among experts. A close comparison of the painting with a forgery by Han van Meegeren and Frans Hals's `Fisherboy' solves the conundrum and provides valuable insights into the merits and drawbacks of modern analytical techniques.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Electron Bessel beam diffraction for precise and accurate nanoscale strain mapping”. Guzzinati G, Ghielens W, Mahr C, Béché, A, Rosenauer A, Calders T, Verbeeck J, Applied physics letters 114, 243501 (2019). http://doi.org/10.1063/1.5096245
Abstract: Strain has a strong effect on the properties of materials and the performance of electronic devices. Their ever shrinking size translates into a constant demand for accurate and precise measurement methods with a very high spatial resolution. In this regard, transmission electron microscopes are key instruments thanks to their ability to map strain with a subnanometer resolution. Here, we present a method to measure strain at the nanometer scale based on the diffraction of electron Bessel beams. We demonstrate that our method offers a strain sensitivity better than 2.5 × 10−4 and an accuracy of 1.5 × 10−3, competing with, or outperforming, the best existing methods with a simple and easy to use experimental setup.
Keywords: A1 Journal article; ADReM Data Lab (ADReM); Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 17
DOI: 10.1063/1.5096245
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