Letizia Monico

Italian National Research Council | CNR · SCITEC Institute of Chemical Sciences and Technologies Giulio Natta

The degradation of cadmium sulfide (CdS)–based oil paints is a phenomenon potentially threatening the iconic painting The Scream (ca. 1910) by Edvard Munch (Munch Museum, Oslo) that is still poorly understood. Here, we provide evidence for the presence of cadmium sulfate and sulfites as alteration products of the original CdS-based paint and explor...

Cadmium red is the name used for denoting a class of twentieth century artists’ pigments described by the general formula CdS 1− x Se x . For their vibrant hues and excellent covering power, a number of renowned modern and contemporary painters, including Jackson Pollock, often used cadmium reds. As direct band gap semiconductors, CdS 1− x Se x com...

The European Synchrotron Radiation Facility (ESRF) has recently commissioned the new Extremely Brilliant Source (EBS). The gain in brightness as well as the continuous development of beamline instruments boosts the beamline performances, in particular in terms of accelerated data acquisition. This has motivated the development of new access modes a...

Redox processes activated by environmental factors have been identified as the main cause of the chromatic alterations of a number of artists’ pigments, including the yellow pigment orpiment (As 2 S 3 ). Although...

Most inorganic pigments, as earths and ochres, have no luminescence emission. Sporadically, the literature has reported the presence of a weak optical emission for some of these pigments. However, this should be attributed to the presence of material impurities within pigments. In addition to this, a small number of inorganic pigments exhibit a cle...

Recent studies in which X-ray beams of (sub)micrometre to millimetre dimensions have been used for non-destructive analysis and characterization of pigments, minute paint samples and/or entire paintings from fifteenth to twentieth century artists are discussed. The overview presented encompasses the use of laboratory and synchrotron radiation-based...

The cultural heritage community is increasingly exploring synchrotron radiation (SR) based techniques for the study of art and archaeological objects. When considering heterogeneous and complex micro-samples, such as those from paintings, the combination of different SR X-ray techniques is often exploited to overcome the intrinsic limitations and s...

Recent opportunities facilitated access to a group of acrylic emulsion (dispersion) paintings originally investigated and aqueous wet- cleaned during the Tate AXA Art Modern Paints Project (TAAMPP, 2006–2009). The 2018–19 re-investigation focused on documenting two key areas of interest for the treatment of acrylic paintings: changes in gloss and t...

In Heritage Science, the evaluation of stone consolidation treatments by investigating the nature of in situ newly formed products and their penetration depth within the consolidated matrix is a grand challenge. A number of analytical methods have been proposed, but, currently, most of them are not able to supply a full overview of the spatial, str...

The nine ceiling paintings at the Banqueting House Whitehall, painted by Peter Paul Rubens and studio is one of the largest and most complex works by the master, and has survived in its original location for almost 400 years. Historic Royal Palaces’ current Banqueting House Whitehall conservation and re-presentation project provided a rare opportun...

Vincent van Gogh's Sunflowers are seen by many as icons of Western European art. Two of these masterpieces - the first version painted in August 1888 (The National Gallery, London) and the painting made after it in January 1889 (Van Gogh Museum, Amsterdam) - have been the subject of a detailed comparison by an interdisciplinary team of experts. The...

Vincent van Gogh's Sunflowers are seen by many as icons of Western European art. Two of these masterpieces — the first version painted in August 1888 (The National Gallery, London) and the painting made after it in January 1889 (Van Gogh Museum, Amsterdam) — have been the subject of a detailed comparison by an interdisciplinary team of experts. The...

Introduction Since its completion by Vincent van Gogh, the Amsterdam Sunflowers has been the subject of a complex history of interventions. Combined with the natural ageing and deterioration of the materials used by the artist, this has strongly affected the present appearance of the painting. The materials and techniques used in Sunflowers and rel...

The darkening due to chemical alteration of chrome yellows (PbCrO 4 /PbCr 1-x S x O 4 ) is a phenomenon threatening a large number of 19th-20th century paintings, including the Amsterdam Sunflowers by Vincent van Gogh. Our earlier studies have proven that the alteration is due to a Cr(VI) a' Cr(III) reduction with Cr(V)-species that are formed as l...

This chapter discusses the potential of reflection mid-FTIR spectroscopy for in situ identification and localization of metal oxalates and carboxylates in paintings. The infrared reflection profiles of the most common metal oxalates and carboxylates are discussed through the direct comparison with reference powders and model samples demonstrating t...

The bleaching of cadmium yellows is a problem that affect paintings by famous artists, such as, Matisse, Van Gogh, and Munch. Synchrotron radiation‐based X‐ray techniques, UV‐Vis, and FTIR spectroscopies unveils the key role played by moisture and light in the discoloration process of cadmium yellow oil paints. The image shows a simplified version...

Cadmium yellows (CdYs) refer to a family of cadmium sulfide pigments which have been widely used by artists since the late 19th c. Despite being considered stable, they are suffering from discoloration in iconic paintings, such as Joy of Life by Matisse, Flowers in a blue vase by Van Gogh and the Scream by Munch, most likely due to the formation of...

Sunflowers, one of the iconic works of Van Gogh, contains two different chrome yellow pigments: the light‐fast monoclinic PbCrO4 (crocoite), and the light‐sensitive monoclinic PbCr1‐xSxO4 (x≈0.5). In their Communication (DOI: 10.1002/anie.201713293), F. Vanmeert et al. describe how they visualized the distribution of these two pigments throughout t...

Die Sonnenblumen von Van Gogh setzen sich aus zwei verschiedenen gelben Chrompigmenten zusammen: lichtechtem monoklinem PbCrO4 (Crocoit) und lichtempfindlichem monoklinem PbCr1−xSxO4 (x≈0.5). In ihrer Zuschrift (DOI: 10.1002/ange.201713293) beschreiben F. Vanmeert et al., wie es ihnen gelang, die Verteilung dieser beiden Pigmente in der Oberfläche...

Sunflowers one of the iconic works of Van Gogh, contains two different chrome yellow pigments: the light‐fast monoclinic PbCrO4 (crocoite), and the light‐sensitive monoclinic PbCr1‐xSxO4 (x≈0.5). In their Communication on page 7418 ff., F. Vanmeert et al. describe how they visualized the distribution of these two pigments throughout the painting's...

The absorption of light gives a pigment its colour and its raison d'être, but it also creates excited states, new molecules with an energy excess that can be dissipated through degradation pathways. Photodegradation processes provoke long‐term, cumulative and irreversible colour changes (fading, darkening, blanching) of which the prediction and pre...

The discoloration rate of chrome yellow (CY), a class of synthetic inorganic pigments (PbCr1-xSxO4) frequently used by Van Gogh and his contemporaries, strongly depends on its sulfate content and on its crystalline structure (either monoclinic or orthorhombic). Macroscopic X-ray powder diffraction imaging of selected areas on Van Gogh's Sunflowers...

Roman-period mummy portraits are considered to be ancient antecedents of modern portraiture. However, the techniques and materials used in their manufacture are not thoroughly understood. Analytical study of the pigments as well as the binding materials helps to address questions on what aspects of the painting practices originate from Pharaonic an...

Recent studies are concisely reviewed, in which X-ray beams of (sub)micrometre to millimetre dimensions have been used for non-destructive analysis and characterization of pigments, minute paint samples, and/or entire paintings from the seventeenth to the early twentieth century painters. The overview presented encompasses the use of laboratory and...

The ID21 beamline (European Synchrotron Radiation facility, France) is a multi micro-analytical platform combining X-ray and infrared micro-probes, for characterization of elements, species, molecular groups and crystalline structures in complex materials. Applications are mainly in the fields of cultural heritage, life science, environmental and e...

Recent studies are concisely reviewed, in which X-ray beams of (sub)micrometre to millimetre dimensions have been used for non-destructive analysis and characterization of pigments, minute paint samples, and/or entire paintings from the seventeenth to the early twentieth century painters. The overview presented encompasses the use of laboratory and...

The in situ non invasive methods have experienced a significant development in the last decade because they meet specific needs of analytical chemistry in the field of cultural heritage where artworks are rarely moved from their locations, sampling is rarely permitted, and analytes are a wide range of inorganic, organic and organometallic substance...

Environmental factors, such as light, humidity and temperature are triggering agents for the alteration of organic and/or inorganic constituents of oil paintings. The oxidation of the organic material is favored by increasing of relative humidity and temperature, whereas processes involving changes of the oxidation states of a number of inorganic p...

This paper presents firm evidence for the chemical alteration of chrome yellow pigments in Van Gogh's Sunflowers (Van Gogh Museum, Amsterdam). Noninvasive in situ spectroscopic analysis at several spots on the painting, combined with synchrotron-radiation-based X-ray investigations of two microsamples, revealed the presence of different types of ch...

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Light-induced redox processes have been established as cause of the chromatic alterations of a number of artists’ pigments used from 15th to 20th century. Despite, the fact that a general comprehension of the mechanisms has been provided through the characterization of the photo-degraded compounds, both exhaustive information on the wavelength-depe...

A combination of synchrotron radiation (SR) micro X-ray fluorescence (μ-XRF) and XRF mode X-ray absorption near edge structure (XANES) measurements at the Cr K-edge already allowed us to establish that the photo-reduction of chromates to Cr(III)-compounds is the cause of darkening of chrome yellow pigments (PbCr1-xSxO4, 0≤x≤0.8) in a number of pain...

The darkening of lead chromate yellow pigments, caused by a reduction of the chromate ions to Cr(III)-compounds, is known to affect the appearance of several paintings by Vincent van Gogh. In previous papers of this series, we demonstrated that the darkening is activated by light and depends on the chemical composition and crystalline structure of...

Recent studies in which X-ray beams of macroscopic to (sub) microscopic dimensions were used for non-destructive analysis and characterization of pigments, paint micro samples and/or entire paintings by Vincent van Gogh are concisely reviewed. The overview presented encompasses the use of laboratory and synchrotron radiation-based instrumentation a...

Chrome yellows, a class of pigments frequently used by painters of the Impressionism and Post-impressionism period, are known for their different chemical stability; the latter depends on the chemical composition (PbCrO4, PbCr1−xSxO4) and crystalline structure (monoclinic or orthorhombic) of the material. The possibility to distinguish among differ...

Getting the picture: The investigation of 100 year old chrome yellow paint by transmission electron microscopy and spectroscopy has led to the identification of four types of core-shell particles. This nanoscale investigation has allowed a mechanism to be proposed for the darkening of some bright yellow colors in Van Gogh's paintings (e.g. in Falli...

of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

In this work a reflection mid-infrared spectroscopy study of twelve metal-oxalate complexes, of interest in art conservation science as alteration compounds, was performed. Spectra of the reference materials highlighted the presence of derivative-like and/or inverted features for the fundamental vibrational modes as result of the main contribution...

We review methods and recent studies in which macroscopic to (sub)microscopic X-ray beams were used for nondestructive analysis and characterization of pigments, paint microsamples, and/or entire paintings. We discuss the use of portable laboratory- and synchrotron-based instrumentation and describe several variants of X-ray fluorescence (XRF) anal...

The painter Vincent van Gogh and some of his contemporaries frequently made use of the pigment chrome yellow that is known to show a tendency towards darkening. This pigment may correspond to various chemical compounds such as PbCrO(4) and PbCr(1-x)S(x)O(4), that each may be present in various crystallographic forms, with different tendencies towar...

Previous investigations about the darkening of chrome yellow pigments revealed that this form of alteration is attributable to a reduction of the original Cr(VI) to Cr(III), and that the presence of sulfur-containing compounds, most often sulfates, plays a key role during this process. We recently demonstrated that different crystal forms of chrome...

Degradation studies of cultural heritage materials using a combination of µ-XANES and µ-XRD Koen Janssens, Letizia Monico, Marie Radepont, Wout De Nolf The mission of cultural heritage institutions is to preserve and protect artifacts from the distant or more recent past for the enjoyment and education of current and future generations. In order...

The darkening of the original yellow areas painted with the chrome yellow pigment (PbCrO(4), PbCrO(4)·xPbSO(4), or PbCrO(4)·xPbO) is a phenomenon widely observed on several paintings by Vincent van Gogh, such as the famous different versions of Sunflowers. During our previous investigations on artificially aged model samples of lead chromate, we es...

Historically, chrome yellow pigment [PrCrO 4, PrCr 1-x S x O 4 or (1-x)PrCrO 4 ·xPbO] is often encountered in oil paintings of the end of 19th Century, such as by Vincent van Gogh (1853-1890) et al [1]. However, in some valuable paintings of the end of 19th Century, the areas painted with chrome yellow now appear darkened, because of the degradatio...