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This paper contributes to current debates on the technologies and practices of prehistoric artists using the rock art site of el Carche (Jalance, Spain) as a case study. The site preserves both Levantine and Schematic paintings, yet poorly understood from an analytical point of view. In the past, it has even been argued how little differentiation there is between these two post-Paleolithic traditions in terms of paint composition. Our aim with this paper was to identify pigments, paint recipes and technologies and decipher the order of the superimpositions, both between Levantine motifs of different styles, and between these and the Schematic ones. To do so, we adopted a multi-stage and multi-technical analytical strategy, trying to find a balance between sound scientific investigation and impact on the art, considering the irreplaceable nature of this World Heritage rock art. As such, our approach begins with in situ non-invasive investigations using portable EDXRF, to then collect micro-samples for non-destructive analyses by means of Optical Microscopy, Scanning Electron Microscopy coupled with Energy Dispersive X-Ray Spectroscopy (SEM-EDX), micro-Raman Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). One of the key highlights of these paper is the identification of up to four different paint compositions, produced with various hematite-based raw materials and different processing techniques. This variability had not been previously documented. Interestingly though, no direct correlations appear to exist between styles or sub-styles and recipes. Some of these paint mixtures were even shared by both traditions. These results are discussed in cultural terms, challenging previous interpretations suggesting a similar pigment composition between Levantine and Schematic art. Microstratigraphic analysis of the cross-sections only partially clarified the overlapping sequence unveiling the complexity of these analysis. They also revealed several degradation layers and external crusts related to rock alteration processes and biological formations. Their role in rock art conservation is also discussed.

This paper offers a broad and critical overview of current discussions on the potential uses and the characterization of pigments in prehistory, with a special focus on prehistoric rock art. Today, analytical approaches to pigments and paints allow us to go beyond the identification of the elemental and molecular composition of these archaeological remains, to explore also raw material procurement, transformation and use strategies of interest to investigate the technological and socio-cultural practices of prehistoric artists and their change over space and time. The paper also summarizes the palette of prehistoric artists, as well as the techniques and analytical strategies used to date to characterize prehistoric pigments and paints (colours, raw materials, binders and recipes) used in prehistoric rock art.

This chapter provides a description of colour changes in the Amsterdam Sunflowers due to chemical alteration of pigments, with a focus on geranium lakes and chrome yellows. The brilliant and forceful colours of these and other late nineteenth-century synthetic materials offered artists such as Vincent van Gogh new means of artistic expression that exploited a range of contrasting hues and tints. However, geranium lakes have a strong tendency to fade and chrome yellows to darken under the influence of light. Van Gogh, like other artists of his day, was aware of this drawback, yet he continued to favour the use of both pigments up until his death in July 1890 due to the unparalleled effects they gave. In April 1888, Vincent wrote to his brother Theo: Van Gogh's use of unstable colours opens a series of questions regarding the extent to which colour change affects the way his paintings look today, as discussed here in relation to the Amsterdam Sunflowers. Furthermore, given the frequency with which geranium lakes and chrome yellows occur in Van Gogh's paintings of the period 1888–90 and the predominance of chrome yellows in Sunflowers, it becomes important to understand the factors that can drive these processes of deterioration in order to develop appropriate strategies for conserving the artist's works.

Science advances 6(20), eaay3514 - (2020). doi:10.1126/sciadv.aay3514, The degradation of cadmium sulfide (CdS)–based oil paints is a phenomenon potentially threatening the iconic paint-ing 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 explore the external circumstances and internal factors causing this transformation. Macroscale in situ noninvasive spectroscopy studies of the painting in combination with synchrotron-radiation x-ray microspectroscopy investiga-tions of a microsample and artificially aged mock-ups show that moisture and mobile chlorine compounds are key factors for promoting the oxidation of CdS, while light (photodegradation) plays a less important role. Furthermore, under exposure to humidity, parallel/secondary reactions involving dissolution, migration through the paint, and re-crystallization of water-soluble phases of the paint are associated with the formation of cadmium sulfates., Published by Assoc., Washington, DC [u.a.]

Geranium lake is an eosin-derived organic pigment highly employed by Van Gogh and his contemporaries. Its elusive behavior, observed in a large number of post-impressionism masterpieces, is of current concern for both conservators and heritage scientists. Herein, the lightfastness of Geranium lake within oil matrix has been investigated by means UV–Vis spectroscopic techniques and HPLC-DAD-HRMS with the final aim of understanding the degradation mechanism behind its marked bleaching. Accelerated photo-aging experiments irradiating with mono/polychromatic light have been carried out on oil paint models prepared with lead eosin-based lakes, in-house synthesized for this purpose according to available historical recipes, alone and in admixture with different white pigments namely, zinc oxide and basic lead carbonate. The aging experiment not only reproduced the fugitive nature of Geranium lake but also evidenced a reversible behavior during the preliminary stages of the light exposure. Succeeding targeted experiments employing monochromatic light as well as a simplified eosin-oil system in solution, corroborated by the wide literature regarding the photophysics of xanthene dyes, allowed us to propose a reasonable fading mechanism of eosin-based lakes, based on the key role played by linseed oil and environmental oxygen.

The philosophical and artistic orientation of Enrico Baj (Italy, 1924–2003) regarding nuclear energy cannot be exclusively reduced to his activism in the Nuclear Art Movement. Baj's interest in science, techniques and technology did not map onto the chronology of this avant-garde movement (1951–1958), but rather was related to the developments in anthropology, philosophy and literature. This studio has as its focus the non-invasive in situ analysis of five of Enrico Baj's paintings which are part of the Archivio Baj collection in Vergiate (Italy): Quamisado II (1951), Bambino magico (1952), Personaggio (1955), Due bambini nella notte nucleare (1956), Spettacolo (1956). Painting materials were investigated thanks to two distinct work sessions of the mobile laboratories of MOLAB-CNR/UNIPG and INFN-CHNet, from October to November 2018. The instruments and know-how of these laboratories were granted to the “Baj Nucleare” project through the access activity to Research Infrastructures offered by E-RIHS.it. This study provided data, which, when cross-checked with previous studies and combined with documents from artistic literature as well as from available secondary sources, have allowed authors to try to better understand Enrico Baj's work process, being able to count on the support of unpublished scientific evidence.

Vincent van Gogh used fugitive red lake pigments that have faded in some paintings. Mapping their distribution is key to understanding how his paintings have changed with time. While red lake pigments can be identified from microsamples, in situ identification and mapping remain challenging. This paper explores the ability of molecular fluorescence imaging spectroscopy to identify and, more importantly, map residual non-degraded red lakes. The high sensitivity of this method enabled identification of the emission spectra of eosin (tetrabromine fluorescein) lake mixed with lead or zinc white at lower concentrations than elemental X-ray fluorescence (XRF) spectroscopy used on account of bromine. The molecular fluorescence mapping of residual eosin and two carmine red lakes in van Gogh's The Olive Orchard is demonstrated and compared with XRF imaging spectroscopy. The red lakes are consistent with the composition of paint tubes known to have been used by van Gogh.

Cadmium yellows (CdYs) refer to a family of cadmium sulfide pigments, which have been widely used by artists since the late 19th century. 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 CdSO4 ⋅n H2 O. The driving factors of the CdYs degradation and how these affect the overall process are still unknown. Here, we study a series of oil mock-up paints made of CdYs of different stoichiometry (CdS/Cd0.76 Zn0.24 S) and crystalline structure (hexagonal/cubic) before and after aging at variable relative humidity under exposure to light and in darkness. Synchrotron radiation-based X-ray methods combined with UV-Vis and FTIR spectroscopy show that: 1) Cd0.76 Zn0.24 S is more susceptible to photooxidation than CdS; both compounds can act as photocatalysts for the oil oxidation. 2) The photooxidation of CdS/Cd0.76 Zn0.24 S to CdSO4 ⋅n H2 O is triggered by moisture. 3) The nature of alteration products depends on the aging conditions and the Cd/Zn stoichiometry. Based on our findings, we propose a scheme for the mechanism of the photocorrosion process and the photocatalytic activity of CdY pigments in the oil binder. Overall, our results form a reliable basis for understanding the degradation of CdS-based paints in artworks and contribute towards developing better ways of preserving them for future generations.

The present research exploits the strengths of external reflection FT-IR spectroscopy to non-invasively study heritage plastic objects through inspection, for the first time, of the wide spectral range including the near- and mid-IR (12500-350 cm−1). Unlike most of previous works on historical plastic objects, reflection-mode spectra were not corrected for the unfamiliar surface reflection profiles to the more recognizable absorption-like band shapes. This avoided data misinterpretation due to ill-suited Kramers Kronig correction when volume reflection is also present or when highly absorbing IR compounds generate Reststrahlen bands. The inspection of the enlarged spectral range allowed the detection of fundamental, combination and overtone bands which provided reliable identification and semi-quantitative characterization of different polystyrene-based co-polymers. Furthermore the variation of the plastic optical properties across the explored spectral range allowed us to sample the plastic materials to different depths in the mid- and near-IR regions, so as to probe the chemistry at the surface and in the plastic bulk, respectively, in a non-invasive manner. This proved particularly useful to observe spectral markers of surface degradation occurring in historical ABS-based polymers.

This chapter provides a description of colour changes in the Amsterdam Vase with Sunflowers due to chemical alteration of pigments, with a focus on geranium lakes and chrome yellows

A two-length scale spectroscopic approach unveils the composition and degradation state of CdS paints in The Scream by Munch., 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 explore the external circumstances and internal factors causing this transformation. Macroscale in situ noninvasive spectroscopy studies of the painting in combination with synchrotron-radiation x-ray microspectroscopy investigations of a microsample and artificially aged mock-ups show that moisture and mobile chlorine compounds are key factors for promoting the oxidation of CdS, while light (photodegradation) plays a less important role. Furthermore, under exposure to humidity, parallel/secondary reactions involving dissolution, migration through the paint, and recrystallization of water-soluble phases of the paint are associated with the formation of cadmium sulfates.

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 opportunity to carry out a first-ever full and systematic technical conservation survey to determine how the paintings were created and how they have changed over the years. In 2018, scaffold access enabled the present technical survey to be conducted in-situ with a non-invasive multi-technique approach using a set of portable instruments. Notably, X-ray fluorescence (XRF) spectroscopy, integrated XRF/X-ray diffraction (XRD), optical coherence tomography (OCT) and FT-IR reflection spectroscopy were employed to study two of the paintings, the large central oval The Apotheosis of King James I (Apotheosis) and the south end rectangle The Wise Rule of King James I (Wise Rule). Results revealed information about the materials used by Rubens and his studio for the production of these large-scale paintings. Pigments identified by XRF and XRD analysis including hydrocerussite, vermillion, smalt, copper-based blue or green pigments, lead-tin yellow and iron oxide-based pigments. OCT and FT-IR analyses provided information about the nature of compounds resulting from the alteration of some original materials and the condition of varnish layers.

Cadmium yellows (CdYs) refer to a family of cadmium sulfide pigments, which have been widely used by artists since the late 19th century. 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 CdSO

This paper offers an updated review of the variety of physicochemical analysis applied so far to Levantine rock art (Spain) to characterize the composition of the pigments, as well as the substrate and/or the natural coating covering these particular prehistoric paintings. This paper is part of a broader special issue evaluating the real contribution of scientific approaches to rock art research, assessing how they have improved our understanding of this particular heritage and the new research questions they open. In this context, and with a focus on Levantine rock art, our aim is to explore: 1. The guiding principles behind the different sorts of analysis conducted and published so far; 2. The non-invasive and invasive techniques applied to answer the research questions raised, and 3. If the result published as yet have met the expectations of rock art researchers. We also reflect on the potential, the limitations and the future developments of this sort of studies, as well as on the ethics and desirable protocols of applying invasive techniques to this UNESCO World Heritage listed archaeological remain. While the focus is Levantine rock art, the discussions raised by this paper and the experiences reported in relation to the various techniques used are of global interest, especially when dealing with open-air rock art.