Paint Tubes Research Articles

Ultramarine Blue in Edvard Munch’s Collection: A Multi-Analytical Study of Early 20th Century Commercial Oil Paints

The recurrence of specific deteriorating phenomena in blue paints used by Edvard Munch, observed more frequently from artworks from 1907 and onwards, calls for an analytical investigation of these paints. Ten commercial Ultramarine blue oil paint tubes from Munch’s studio materials were studied, employing a multi-analytical approach comprising ATR-FTIR, µ-Raman, GC-MS, and SEM-EDS techniques. This study aims to ascertain the composition of these industrially produced blue oil paints and shed more light on the potential implications for darkening and other deterioration phenomena observed in Munch’s artworks. The analyzed samples exhibited complex mixtures, characterized by significant presences of additives such as non-drying or partially drying oils, metal soaps, and preservatives. Moreover, extenders including clay minerals and white and other blue pigments were identified. Some compositions diverged from those indicated on the labels of the tubes. This study presents hypotheses regarding the causes of deterioration mechanisms observed in Ultramarine blue paints and outlines future perspectives and implications of darkening and other surface degradation phenomena in paintings from MUNCH’s collection towards best conservation and display practices.

A study of cadmium yellow paints from Joan Miró’s paintings and studio materials preserved at the Fundació Miró Mallorca

The deterioration of cadmium yellow paints in artworks by Joan Miró (1893–1983) and in painting materials from his studios in Mallorca (Spain) was investigated. Analysis of samples from Miró’s paintings and from paint tubes and palettes showed that degraded paints are composed of poorly crystalline cadmium sulfide/zinc cadmium sulfide (CdS/Cd1−xZnxS) with a low percentage of zinc, in an oil binding medium. Cadmium sulfates were identified as the main deterioration products, forming superficial white crusts detected using SR µXANES and µXRD techniques. Time-resolved photoluminescence measurements demonstrated that highly degraded samples display a pink/orange emission from the paint surface with a microsecond lifetime, a phenomenon observed in other degraded cadmium yellow paints. In agreement with recent studies on altered cadmium paints, these results suggest that the stability of the paint is related to its manufacturing method, which affects the degree of crystallinity of the resulting pigment. This, together with the environmental conditions in which artworks have been exposed, have induced the degradation of yellow paints in Miró’s artworks. It was finally noted that the paints exhibiting alteration in the analysed Miró artworks have a chemical composition that is very similar to the tube paint ‘Cadmium Yellow Lemon No. 1’ produced by Lucien Lefebvre-Foinet. Indeed, paint tubes from this brand were found in the studio, linking the use of this product with Miro’s degraded artworks.

A First Approach to the Study of Winsor & Newton’s 19th-Century Manufacture of Madder Red Lake Pigments

This paper focuses on the first investigation of the 19th-century manufacture of red lake pigments obtained from madder by Winsor & Newton (W&N), prominent artists’ colourman at that time. The first approach to their manufacture was carried out by studying the madder entries of the company’s book P1, found in the W&N 19th Century Archive Database. Eleven production records were discovered under names such as Rose Madder, Madder Carmine, Madder Lake and Madder Rose. Three main methods of synthesis were identified and reproduced, revealing three main steps: washing of the madder roots (Rubia tinctorum L.); extraction in acid media and complexation with Al3+ using alum; and precipitation by the addition of salts such as ammonium carbonate and sodium borate. The syntheses were followed by UV-VIS spectroscopy, and the pigments were further characterised by colourimetry, Energy-Dispersive X-Ray Fluorescence Spectrometry (XRF), Fourier Transform Infrared Spectroscopy (FTIR) and High-Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD). They all exhibited a rose hue in a highly insoluble aluminate matrix. Although the dye extraction was incomplete, alizarin, purpurin and pseudopurpurin were identified. An analytical comparison with a Rose Madder 19th-century oil paint tube was also performed by micro-FTIR and microspectrofluorimetry. This work intends to be foundational to a systematic study of the W&N’s 19th-century madder colours aiming to contribute new knowledge towards their identification and preservation in heritage objects.

Micro-spectroscopic study of late 19th-early 20th century tube paints

Many issues in the conservation of paintings from the early modern period are still unresolved due to lack of information on paints from the late 19th and early 20th centuries, in particular their production, formulations, and later degradation processes. The inconsistency of the names that paint manufacturers chose for their products furthermore compounds the challenges faced by conservators and chemists wishing to study them. This paper addresses a number of these issues through investigations of commercial tube oil paints from a paint box owned by the Norwegian painter Harriet Backer (1845–1932). Samples were analyzed using a multi-instrumental approach. Micro-attenuated total reflection Fourier transform infrared spectroscopy and micro-Raman spectroscopy – supported by micro-X-ray powder diffraction – allowed the identification of binders, pigments, and extenders. The data highlight the use of materials that were new at the time and not reported in the manufacturer’s catalog. Furthermore, zinc stearate has been detected for the first time. Its detection and the absence of any zinc-based pigments confirms that zinc stearate was already used as dispersing agent in paint formulations at that time.

Evolution of Liu Kang’s Palette and Painting Practice for the Execution of Female Nude Paintings: The Analytical Investigation of a Genre

The comprehensive technical investigation of female nude paintings by the Singapore pioneer artist Liu Kang (1911–2004) provided the evidence for a discussion of the evolution of his palette of colours and his working process for expression in this genre, particularly the execution of female bodies. As the artist’s free expression in classical nude paintings was limited by the censorship imposed by the Singapore government, the investigated artworks span two periods, 1927–1954 (early career) and 1992–1999 (the “golden years”, during which censorship policies were relaxed). Hence, eight paintings from the Liu family and National Gallery Singapore were selected for non- and micro-invasive analyses of the paint layers. The obtained results were supplemented with archival sources to elucidate certain aspects of Liu Kang’s working practice. The investigation revealed the importance of drawing and sketching studies in the development of artistic ideas. The analytical techniques, such as polarised light microscopy (PLM), field emission scanning electron microscope with energy dispersive spectroscopy (FE-SEM-EDS) and attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), enabled us to observe a transition from the yellow iron-based tonal ranges of skin colours to complex pigment mixtures composed of additions of cobalt blue, ultramarine, Prussian blue, Cr-containing yellow(s) and green(s), cadmium yellow, orange and/or red and organic reds, revealing the artist’s more liberal use of colours and his experimentation with their contrasting and complementary juxtaposes. In terms of painting technique, the artist’s comparatively laborious paint application using small brushes quickly gave way to a more effortless manipulation of the paint using bigger brushes and the incorporation of palette knives. Moreover, visible light (VIS), near-infrared (NIR) and X-ray radiography (XRR) imaging techniques led to the discovery of a hidden composition in one investigated artwork, which bears resemblance to the nude painting known only from an archival photograph. Additionally, for the first time, the archival search provided photographic evidence that Liu Kang used oil paint tubes from Royal Talens and Rowney in the 1990s. Overall, this in-depth investigation contributes to the understanding of Liu Kang’s approach to the female nude painting and may assist conservators and art historians in studies of twentieth-century commercial paints.

Analytical approaches for the characterization of early synthetic organic pigments for artists’ paints

Several analytical techniques have shown use for the identification of historical synthetic organic pigments (SOPs) in samples. However, as the techniques differ—for example, in the extent of sample intervention, modes of detection, and limits of detection—so do they differ in results and insights into the colorants and colorant derivatives in a sample. Liquid chromatography (LC) is infrequently applied to the task of SOP identification, despite its ability to differentiate similar molecules, detect at low concentrations, and separate of complex samples and its established usage for organic dyes. This research compared results obtained with micro-Raman spectroscopy and pyrolysis gas chromatography with results from ultra-high performance (UP)LC coupled with photodiode array detection (UPLC-PDA), and high resolution mass spectrometry (UPLC-HRMS) to judge the quantity and quality of SOP information obtained by each technique.In this study, 67 historical samples were analyzed from historical samples and sample books (1918–1950), consisting of 10 oil paint tubes, 45 oil-bound paint-outs, and 13 gum-bound pigment washes using sample sizes less than a milligram. As few studies have used LC for SOP identification, special attention is also paid to issues around sample preparation and interpretation of results from UPLC-PDA and UPLC-PDA-HRMS results. Finally, archival sources and other contemporary documents are used to contextualize and evaluate the plausibility of the analytical results. The results indicate that specific combinations of analytical techniques are required for confident SOP identifications. While Raman results were accurate and independent of sample solubility, they relied heavily on database completeness and were not sensitive to mixtures or differences in relative amounts of SOPs. UPLC-PDA was an effective complement for these shortcomings, except for a few samples that were insoluble. The use of HRMS was critical for the elucidation of unknown SOPs.

Development of a GC–MS strategy for the determination of cross-linked proteins in 20th century paint tubes

In this paper we present the technical study of protein-drying oil mixtures in the paint formulation of original manufacturers paint tubes from Fabbrica di colori per Belle Arti Maimeri dating back to the 1950s. The study is part of a wider research project aimed at understanding the chemistry of protein-drying oil mixtures, and how the oil curing in the presence of proteins may affects the protein analysis with mass spectrometric based techniques.Tempera grassa, according to traditional Late Medieval and Renaissance painting techniques, entails the use, as paint binder, of a mixture of a drying oil with a water miscible medium, commonly egg. The paints analysed in this study were, according to technical documentation available at the manufacturer, based on a mixture of linseed oil, ovalbumin and mastic resin. All the components of the paints were detected but proteins proved very challenging. They could not be detected by pyrolysis coupled to gas chromatography-mass spectrometry, nor by using classical procedures for gas chromatography – mass spectrometry analysis of amino acids after hydrolysis. A new analytical procedure based on two subsequent hydrolysis steps assisted by microwaves was implemented and proved to be successful. The first step with trifluoroacetic acid was aimed at a partial hydrolysis of proteins into peptides, for their efficient extraction. The second with hydrochloric acid in the vapour phase was used for a complete hydrolysis of peptides into amino acids for the GC–MS analysis. Linking experimental results on the tempera grassa paints to data obtained on the curing of oil/protein mixtures in paint mock-ups, the hypothesis that copolymerisation of proteins and the oil has taken place is proposed, and a discussion on how this may affect protein detection is carried out.

Landing on the moon 50 years later: A multi-analytical investigation on Superficie Lunare (1969) by Giulio Turcato

Giulio Turcato (Mantova 1912–Rome 1995) was an Italian artist, belonging to the figurative and abstract expressionist currents. At the end of the 1960s, fascinated by the US space program, Turcato produced a series of artworks, differing in colour and shape, titled Superficie Lunare (Moon Surface). To reproduce a realistic moon surface, Turcato used polyurethane foam as support for the painting. The combination of this unconventional material and the pictorial ones makes Superficie Lunare an interesting case of study to understand the alteration phenomena in contemporary art. In this study, a blue painted Superficie Lunare (1969) was analysed by means of non-invasive (ER-FTIR, Raman and X-ray spectroscopy) and micro-invasive techniques (µ-ATR, μ-FTIR, μ-Raman, Py-GC/MS, EGA-MS and SEM-EDS). The results point out the use of a polyurethane foam as support and of a poly(vinyl acetate) based Prussian blue paint tube as main constituent of the paint layer. The analyses highlight also the complexity of the paint layer, showing the presence of lampblack and Al foil mixed to the blue paint, lithopone inside the white crater and possibly ferric oxide in the red one. The results confirm the use of a polyurethane foam for the support. The painted layers present a binder composed of poly(vinylacetate), with polystyrene, possibly present as additive. Concerning the nature of the blue pigment, Prussian blue was identified on the whole surface. In some points, also lampblack was detected. Furthermore, small foils of Al were found inside the paint layer, probably to give sparkling effect. Inside the moon craters, lithopone was identified for the white pigment and possibly iron oxide for the red one. The multi-technique approach allowed also to obtain information about the manufacturing of the used Prussian blue and the occurrence of alteration process for the polyurethane foam.

Molecular Fluorescence Imaging Spectroscopy for Mapping Low Concentrations of Red Lake Pigments: Van Gogh's Painting The Olive Orchard

AbstractVincent 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.

Molecular Fluorescence Imaging Spectroscopy for Mapping Low Concentrations of Red Lake Pigments: Van Gogh's Painting The Olive Orchard.

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.

An integrated diagnostic approach to Max Ernst's painting materials in his Attirement of the Bride

Abstract The Attirement of the Bride, painted by Max Ernst in 1940, is permanently on display in the Peggy Guggenheim Collection (PGC) in Venice. Within the framework of a larger study of materials and techniques of works by Ernst at the PGC, researchers carried out a series of non-invasive analyses. A combined approach based on Vis-NIR multispectral imaging, Raman Spectroscopy, X-Ray Fluorescence (XRF), and External Reflection Fourier Transform Infrared Spectroscopy (ER-FTIR), was conducted insitu in the museum galleries. In addition, two micro-samples were analysed with SEM-EDS and μ-Raman. This approach produced vital information on the preparatory drawing, the pentimenti, the pigments, the extenders and the alteration products present in the painting. The results showed also the presence of a white preparatory layer, under the pictorial one and above the canvas, composed by lithopone (a mixture of zinc sulphide and barium sulphate), basic lead carbonate and calcium carbonate. The latter compound is probably present also as an extender. The palette included both traditional and new synthetic, commercial pigments, used as primary colours or in mixtures. Moreover, in several areas of the painting, zinc oxalates have been identified as alteration products and more rarely, zinc metal soaps, which could also be present as additives in the paint tube. These analyses revealed the masterful and innovative painting technique of this pioneer of Surrealism.

Unveiling Harriet Backer: ICP\u2013OES study for the characterisation of the colour tubes from her original paint box

Micro-samples from 57 original paint tubes used between 1904 and 1909 by the Norwegian painter, Harriet Backer were studied with inductively coupled plasma–optical emission spectroscopy (ICP–OES). This accurate elemental characterisation of Backer’s original materials aims to fill several gaps in conservation science, painting conservation, and art technology. Firstly, it provides a novel and validated analytical method that can be applied to other painting materials. Secondly, ICP–OES offers scientific information about different oil colours from the late 19th to the early 20th century by Dr. Schoenfeld & Co., Düsseldorf, currently known as Lukas–Nerchau, whose archives were depleted during the Second World War. This work also lends new insights into the paintings of a renowned female Norwegian artist, whose painting materials have been little studied to date. ICP–OES results, coupled with a comprehensive, illustrated catalogue of paint tubes, will be instrumental for ongoing scientific investigations of this painter’s body of work.

Pigment and Binder Concentrations in Modern Paint Samples Determined by IR and Raman Spectroscopy.

Knowledge of the techniques employed by artists, such as the composition of the paints, colour palette, and painting style, is of crucial importance not only to attribute works of art to the workshop or artist but also to develop strategies and measures for the conservation and restoration of the art. While much research has been devoted to investigating the composition of an artist's materials from a qualitative point of view, little effort has been made in terms of quantitative analyses. This study aims to quantify the relative concentrations of binders (acrylic and alkyd) and inorganic pigments in different paint samples by IR and Raman spectroscopies. To perform this quantitative evaluation, reference samples of known concentrations were prepared to obtain calibration plots. In a further step, the quantification method was verified by additional test samples and commercially available paint tubes. The results obtained confirm that the quantitative method developed for IR and Raman spectroscopy is able to efficiently determine different pigment and binder concentrations of paint samples with high accuracy.

Pigment and Binder Concentrations in Modern Paint Samples Determined by IR and Raman Spectroscopy

AbstractKnowledge of the techniques employed by artists, such as the composition of the paints, colour palette, and painting style, is of crucial importance not only to attribute works of art to the workshop or artist but also to develop strategies and measures for the conservation and restoration of the art. While much research has been devoted to investigating the composition of an artist's materials from a qualitative point of view, little effort has been made in terms of quantitative analyses. This study aims to quantify the relative concentrations of binders (acrylic and alkyd) and inorganic pigments in different paint samples by IR and Raman spectroscopies. To perform this quantitative evaluation, reference samples of known concentrations were prepared to obtain calibration plots. In a further step, the quantification method was verified by additional test samples and commercially available paint tubes. The results obtained confirm that the quantitative method developed for IR and Raman spectroscopy is able to efficiently determine different pigment and binder concentrations of paint samples with high accuracy.

Paint tubes: cinéma vérité as representation

This essay explores the gap separating early conceptions of cinéma vérité from the ones which circulated in the wake of Jean Rouch and Edgar Morin’s ground-breaking film Chronique d’un été/Chronicle of a Summer (1961). Initially, the author returns to Morin’s understanding of the phrase, which appears in his writing towards the end of the 1950s. He then examines how the ideas and practices Chronique introduced were codified in three conventional productions from the following decade: Jacques Baratier’s musical comedy Dragées au poivre/Sweet and Sour (1963), John Schlesinger’s Darling (1965) and Jean-Luc Godard’s Le Grand Escroc (1963). While Rouch and Morin’s innovations shaped the look of documentary and fiction within the French context, divergent understandings of cinéma vérité also infiltrated the narratives of commercial films at the time, and the term became a recognisable theme in its own right almost immediately. The author argues that Baratier’s, Schlesinger’s and Godard’s successive representations of this new style register fundamental changes that were taking place in French cinema, changes concerning the nature of the moving image and its purpose in society.

Development of a GC/MS method for the qualitative and quantitative analysis of mixtures of free fatty acids and metal soaps in paint samples

In this paper we present a new analytical GC/MS method for the analysis of mixtures of free fatty acids and metal soaps in paint samples. This approach is based on the use of two different silylating agents: N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1,1,1,3,3,3-hexamethyldisilazane (HMDS).Our experimentation demonstrated that HMDS does not silylate fatty acid carboxylates, so it can be used for the selective derivatization and GC/MS quantitative analysis of free fatty acids. On the other hand BSTFA is able to silylate both free fatty acids and fatty acids carboxylates. The reaction conditions for the derivatization of carboxylates with BSTFA were thus optimized with a full factorial 32 experimental design using lead stearate and lead palmitate as model systems. The analytical method was validated following the ICH guidelines. The method allows the qualitative and quantitative analysis of fatty acid carboxylates of sodium, calcium, magnesium, aluminium, manganese, cobalt, copper, zinc, cadmium, and lead and of lead azelate. In order to exploit the performances of the new analytical method, samples collected from two reference paint layers, from a gilded 16th century marble sculpture, and from a paint tube belonging to the atelier of Edvard Munch, used in the last period of his life (1916–1944), were characterized.

HPLC-DAD and HPLC-ESI-Q-ToF characterisation of early 20th century lake and organic pigments from Lefranc archives

The characterisation of atelier materials and of the historical commercial formulation of paint materials has recently gained new interest in the field of conservation science applied to modern and contemporary art, since modern paint materials are subjected to peculiar and often unpredictable degradation and fading processes. Assessing the composition of the original materials purchased by artists can guide not only their identification in works of art, but also their restoration and conservation. Advances in characterisation methods and models for data interpretation are particularly important in studying organic coloring materials in the transition period corresponding to the late 19th–early 20th century, when many such variants or combinations were hypothetically possible in their formulations. There is thus a need for reliable databases of materials introduced in that period and for gaining chemical knowledge at a molecular level related to modern organic pigments, by state-of-the-art protocols. This paper reports on the results of a study on 44 samples of historical colorants in powder and paint tubes, containing both lake pigments and synthetic organic pigments dating from 1890 to 1926. The samples were collected at the Lefranc Archive in Le Mans (France) as a part of Project Futurahma “From Futurism to Classicism (1910–1922). Research, Art History and Material Analysis”, (FIRB2012, Italian Ministry of University and Research), and were investigated using an analytical approach based on chromatographic and mass spectrometric techniques. The focus of the chemical analyses was to reveal the composition of the historical organic lake pigments including minor components, to discriminate between different recipes for the extraction of chromophore-containing molecules from the raw materials, and ultimately to distinguish between different formulations and recipes. High performance liquid chromatography (HPLC) with diode array detector (DAD) or electrospray-Quadrupole-Time of Flight tandem mass spectrometry detector (ESI-Q-ToF) were chosen given their considerable capacity to identify such complex and widespread organic materials. Although the inorganic components of the pigments were not taken into account in this survey, the specific molecular profiles provided invaluable information on the extraction procedures or synthetic strategy followed by the different producers, at different times. For instance, the use of Kopp’s purpurin and garancine was highlighted, and synthetic by-products were identified. The results provided evidence that the addition of synthetic organic pigments to paint mixtures started from 1910 onwards, but they also suggest that in the formulation of high quality (surfin) colorants, natural products were still preferred. Moreover, in one of the samples the use of murexide as the colouring material was confirmed. This paper presents the first systematic and comprehensive survey on organic lakes and pigments belonging to an historical archive, by both HPLC-DAD and HPLC-ESI-Q-ToF. Specific by-products of synthetic production of pigments, which can act as specific molecular markers for dating or locating a work of art, were also identified for the first time.Graphical abstractHPLC-DAD chromatograms of the DMSO extracts of samples of organic pigments from the Lefranc historical archives, acquired 430 nm.

Revealing the Nature and Distribution of Metal Carboxylates in Jackson Pollock's Alchemy (1947) by Micro-Attenuated Total Reflection FT-IR Spectroscopic Imaging.

Protrusions, efflorescence, delamination, and opacity decreasing are severe degradation phenomena affecting oil paints with zinc oxide, one of the most common white pigments of the 20th century. Responsible for these dramatic alterations are the Zn carboxylates (also known as Zn soaps) originated by the interaction of the pigment and the fatty acids resulting from the hydrolysis of glycerides in the oil binding medium. Despite their widespread occurrence in paintings and the growing interest of the scientific community, the process of formation and evolution of Zn soaps is not yet fully understood. In this study micro-attenuated total reflection (ATR)-FT-IR spectroscopic imaging was required for the investigation at the microscale level of the nature and distribution of Zn soaps in the painting Alchemy by J. Pollock (1947, Peggy Guggenheim Collection, Venice) and for comparison with artificially aged model samples. For both actual samples and models, the role of AlSt(OH)2, a jellifying agent commonly added in 20th century paint tube formulations, proved decisive for the formation of zinc stearate-like (ZnSt2) soaps. It was observed that ZnSt2-like soaps first form around the added AlSt(OH)2 particles and then eventually grow within the whole painting stratigraphy as irregularly shaped particles. In some of the Alchemy samples, and diversely from the models, a peculiar distribution of ZnSt2 aggregates arranged as rounded and larger particles was also documented. Notably, in one of these samples, larger agglomerates of ZnSt2 expanding toward the support of the painting were observed and interpreted as the early stage of the formation of internal protrusions. Micro-ATR-FT-IR spectroscopic imaging, thanks to a very high chemical specificity combined with high spatial resolution, was proved to give valuable information for assessing the conservation state of irreplaceable 20th century oil paintings, revealing the chemical distribution of Zn soaps within the paint stratigraphy before their effect becomes disruptive.

Micro‐Raman and SER spectroscopy to unfold Lefranc's early organic pigment formulations

The introduction of synthetic dyes and pigments into commerce in the late 19th century was a stimulating time for experimental scientists in their laboratory formulations and for artists in their usage. Nowadays, the period of pioneering syntheses and employment of synthetic organic colouring materials is highly intriguing for scientific research and for conservation purposes in heritage science. In this work, a combination of spectroscopic and chromatographic methods has permitted the elucidation of the chemical composition of 16 early synthetic organic pigment powders from the Lefranc experimental laboratory collection dating 1890–1914. It can be hypothesized that the most successful of these formulations could have been finalized in paint tubes and released onto the market, meaning that they may even be found in artworks from the same period.Specifically, information from this crucial period of transition from the exclusive use of natural dyes/colourants (such as neoflavonoids and plant and insect anthraquinones) to the introduction of their synthetic counterparts (such as synthetic alizarin and purpurin, and acid stable cochineal, together with monoazo and diazo pigments) is confirmed through Raman/surface‐enhanced Raman spectroscopy and high‐performance liquid chromatography with diode array detection. By means of X‐ray fluorescence and mid‐Fourier transform infrared spectroscopy, a combination of traditional and modern inorganic substrates has been identified (alum, kaolin, barium sulfate and metallic salts), while Raman has provided additional data regarding the possible complexation of these pigments in the form of lakes. Copyright © 2016 John Wiley & Sons, Ltd.

Nineteenth century chrome yellow and chrome deep from Winsor & NewtonTM

The Winsor & NewtonTM (W&N) nineteenth century archive database includes digitised images of hand-written instructions and workshop notes for the manufacture of their artists’ materials. For the first time, all 183 production records for yellow lead chromate pigments were studied and evaluated. They revealed that W&N produced essentially three pigment types: lemon/pale based on mixed crystals of lead chromate and lead sulphate [Pb(Cr,S)O4]; middle on pure monoclinic lead chromate [PbCrO4]; and deep that contains the latter admixed with basic lead chromate [Pb2CrO5]; accounting for 53, 22, and 21% of the production, respectively. Production records for primrose (4%) were also included since the formulation results in mixed crystals with a high percentage of lead sulphate, which, according to the literature, leaves it more prone to degradation. Each pigment type is characterised by only one or two main synthetic pathways; process variations reveal a systematic and thorough search for a high-quality durable product. A comparison of the chemical composition of pigment reconstructions with early W&N oil paint tubes showed that their records entitled ‘pale’ and ‘lemon’ correlated with the pigment in their tube labelled chrome yellow and, ‘middle’ and ‘deep’ with the label chrome deep. Lemon and middle pigment formulations were made into oil paints to assess their relative photo-stability. The degradation process was followed by colorimetry and was studied by synchrotron radiation-based techniques. Based on the X-ray absorption spectroscopy data, the possibility for creating a stability index for chrome yellows is discussed.