Chrome Yellow Research Articles

Study on colored pattern pigments of a royal Taoist temple beside the Forbidden City (Beijing, China)

The colored pattern pigment of Dagaoxuan Taoist Temple which was the royal temple of Ming and Qing dynasties (1368–1912) in China was studied for the first time.Fifteen samples were identified by the combined use of SEM-EDS, Raman spectrum and Polarized light microscopy. The results revealed that, the red pigments included hematite, cinnabar, minium and realgar. The blue pigments included lazurite and ultramarine. The green pigments included olivenite and emerald green. The yellow pigments included orpiment and chrome yellow. The black pigment was carbon and the white pigments included gypsum and hydrocerussite. The study showed that more than one type pigment was used for the same color except black, which may be attributed to the history of multiple repairs. In addition, it was necessary to combine the use of two or more test methods for identifying cultural relic samples composed of multiple substances, which played an important role in exploring the true and accurate historical information of this architectural treasure that has never been studied.

Detection and imaging of chrome yellow (lead chromate) in latent prints, solid residues, and minerals by laser-desorption/ionization mass spectrometry (LDI-MS).

In the past, chrome yellow (lead chromate, PbCrO4 ), a bright orange-red substance, has been widely used as an inorganic pigment in the production of paints, coatings, and plastics. Herein, we demonstrate that laser desorption/ionization mass spectrometry (LDI-MS) is a powerful tool for the detection of lead chromate in solid residues. In fact, lead chromate in trace amounts is easily detectable by LDI-MS even from residues left as latent prints. For example, a latent print obtained by stamping the exposed laterally cut surface of a pencil over 50years old on an acetonitrile-moistened paper, was successfully imaged for both lead and chromate using a Synapt G2 HDMS mass spectrometer. After rastering the print with a 355 nm laser beam and recording positive- and negative-ion mass spectra over the range m/z 50-1200, we generated false-color 'heat maps' (single-ion images) for 208 Pb+• (m/z 207.98) and Cr2 O6-• (m/z 199.85). The heat maps matched closely with the faint visual image of the pencil imprint. Moreover, our results confirmed that lead chromate was used in the pigment coatings of old pencils. Evidently, LDI-MS imaging is an efficient procedure to survey for the presence of lead and chromate in minerals and other materials. Copyright © 2017 John Wiley & Sons, Ltd.

A MULTIPLEX RT-PCR FOR SIMULTANEOUS DETECTION OF THE AGENTS OF YELLOW SPECKLE AND VEIN BANDING DISEASES IN GRAPEVINE

Six viroids have been reported to infect grapevine and among them only Grapevine yellow speckle viroid-1 (GYSVd-1) and Grapevine yellow speckle viroid-2 (GYSVd-2) are able to induce yellow speckle (YS) disease, characterized by yellowish flecks scattered on the leaf blade or massed along the veins. The mixed infection of GYSVd-1 or GYSVd-2 with Grapevine fanleaf virus (GFLV) may elicit vein banding (VB), a syndrome characterized by chrome-yellow flecks along the main veins of mature leaves and expanding through the interveinal tissues of infected leaves. In the present study, we have developed a multiplex RT-PCR (mRT-PCR) for simultaneous detection of GYSVd-1, GYSVd-2 and GFLV. Hop stunt viroid (HSVd), another viroid that infecting most grapevines worldwide is used as a positive control instead of a host- derived internal control. The test developed here proved to be reliable for simultaneous detection of three pathogens, i.e. GYSVd-1, GYSVd-2 and GFLV, in grapevine; hence it is useful for detection of YS and VB in large-scale surveys and certification programs.

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.

Structural and electronic properties of the PbCrO4 chrome yellow pigment and of its light sensitive sulfate-substituted compounds

Chrome Yellows (CY) are a family of synthetic pigments of formula (PbCr(1−x)SxO4) used by van Gogh. We investigate structure/property relations in CY by first-principles methods, providing insight into their possible degradation mechanisms.

Evidence for Degradation of the Chrome Yellows in Van Gogh's Sunflowers: A Study Using Noninvasive In Situ Methods and Synchrotron-Radiation-Based X-ray Techniques.

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 chrome yellow used by Van Gogh, including the lightfast PbCrO4 and the sulfur-rich PbCr1-x Sx O4 (x≈0.5) variety that is known for its high propensity to undergo photoinduced reduction. The products of this degradation process, i.e., Cr(III) compounds, were found at the interface between the paint and the varnish. Selected locations of the painting with the highest risk of color modification by chemical deterioration of chrome yellow are identified, thus calling for careful monitoring in the future.

Evidence for Degradation of the Chrome Yellows in Van Gogh’s Sunflowers: A Study Using Noninvasive In Situ Methods and Synchrotron‐Radiation‐Based X‐ray Techniques

AbstractThis 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 chrome yellow used by Van Gogh, including the lightfast PbCrO4 and the sulfur‐rich PbCr1−xSxO4 (x≈0.5) variety that is known for its high propensity to undergo photoinduced reduction. The products of this degradation process, i.e., CrIII compounds, were found at the interface between the paint and the varnish. Selected locations of the painting with the highest risk of color modification by chemical deterioration of chrome yellow are identified, thus calling for careful monitoring in the future.

A combined analytical approach applied to Medieval wall paintings from Puglia (Italy): The study of painting techniques and its conservation state

A combined analytical approach has been applied to the wall paintings, dated from 10th to 14th centuries, of the Santi Stefani crypt at Vaste (Lecce, Southern Italy). These paintings are a precious testimony of Medieval art in Southern Italy. However, the church shows problems of damp as well as clear evidences of flora, fungi and mold presence, and there is little knowledge of the pictorial methodologies used. Raman spectroscopy allowed to determine the palette and to reconstruct the worksite and the chronological sequence of the various paint layers. Kaolinite, calcite, carbon black, hematite, massicot, goethite, indigo and azurite were identified as pigments along with synthetic pigments, like phthalocyanine blue and chrome yellow. Attenuated total reflectance-Fourier transform infrared spectroscopy suggested the presence of egg as a binder in some pictorial layers. The conservation state of the crypt is poor, and detachments of pigmented layers are frequent because of the presence of subflorescence and efflorescence: nitrate, sulfate and chloride salts have been identified spectroscopically and quantified by ion chromatography. The extensive use of kaolinite in Santi Stefani, actually not uncommon in Medieval art, is observed for the first time in a crypt of Puglia: its use to stabilize some pigments and to improve their adhesion on substrate is proposed. Copyright © 2015 John Wiley & Sons, Ltd.

Non-destructive identification of pigments printed on six Imperial China Engraved Coiling Dragon stamps

Raman spectroscopy was employed to investigate six Imperial China Engraved Coiling Dragon stamps non-destructively. The results have shown that (1) the main colors (yellow, green, scarlet, brown, vermilion, and blue) on the six stamps were all prepared from inorganic pigments, including chrome yellow, chrome orange, Prussian blue, red lead, magnesium sulfate hydrate, and ultramarine blue. (2) Raman spectrometer has been allowed for successfully identifying the molecular structure of the pigments printed on the six examined stamps, suggesting that such a dual analytical approach could satisfy the need for pigment identification on stamps. (3) The finding that certain pigments were intentionally mixed to produce a whole different hue or color, the mechanism of which could be explained by theories of chromatology and metamerism, also provides new insight into the future conservation, authentication, and restoration of the early printings. Copyright © 2015 John Wiley & Sons, Ltd.

GRAPEVINE VIROIDS AND GRAPEVINE FANLEAF VIRUS IN NORTH- WEST IRAN

Grapevine-infecting viroids do not induce symptoms, except for Grapevine yellow speckle viroid-1 (GYSVd-1) and Grapevine yellow speckle viroid-2 (GYSVd-2), the agents of yellow speckle (YS), a disease characterized by yellow spots or flecks scattered on the leaf blade. The association of these viroids with Grapevine fanleaf virus (GFLV) is thought to elicit vein banding (VB), a syndrome characterized by chrome yellow flecks localized along the main veins and progressing into the interveinal areas of affected vines. The occurrence of these diseases and their causal agents was investigated in north-west Iran with a survey in which 137 vines were tested by multiplex RT-PCR for the presence of the five known grapevines viroids. GYSVd-1, GYSVd-2, Australian grapevine viroid (AGVd) and Hop stunt viroid (HSVd) were detected in 91%, 64%, 95%, and 100% of the tested samples, respectively, whereas Citrus exocortis viroid (CEVd) was not found. Combinations of three and four different viroids were present in most plants (88%) whereas GFLV was found in 50 samples (37%). The Iranian isolates of GYSVd-1, GYSVd-2, HSVd and AGVd showed minor molecular changes compared with the respective reference strains from grapevine. VB occurred in 22 vines infected by GYSVd-1, GYSVd-2 and GFLV, whereas YS symptoms, which occurred in 10% of the tested plants, were always shown by vines infected by GYSVd-1 and/or GYSVd-2. These findings are in line with the notion that assigns to GYSVd-1 and GYSVd-2 a role in the induction of YS and to both viroids and GFLV the genesis of VB.

Raman analysis of complex pigment mixtures in 20th century metal knight shields of the Order of the Elephant

The pigment composition of six painted metal knight shields of the Order of the Elephant dating from the second half of the 20th century belonging to the Danish royal collection were studied using Raman microscopy. By focusing a 785nm laser with a 50× objective on particles in paint cross sections, it was possible to identify the following 20 compounds: hematite, goethite, chrome red/orange, chrome yellow, zinc chrome yellow, carbon black, toluidine red PR3, chlorinated para red PR4, dinitroaniline orange PO5, phthalocyanine blue PB15, indanthrone blue PB60, ultramarine, Prussian blue, lead white, anatase, rutile, calcium carbonate, barium sulphate, gypsum and dolomite. The components were frequently present in complex pigment mixtures. Additional information was obtained by elemental analysis with scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) to identify cobalt blue, zinc white and cadmium red, as well as to indicate the presence of zinc white in some pigment mixtures. The study allowed a comparison between the industrially applied preparation layers and the artistic paint layers applied by the heraldic painter. Differences in the choice of paint and pigment types were observed on the earliest knight shields, demonstrating a general delay of industrial materials into artist paints.

Variable-Temperature Micro-Raman Spectra of the Synthetic Artists' Pigments, Chrome Yellow and Maya Blue: An Undergraduate Research Project

As part of an undergraduate summer research project in vibrational spectroscopy, the micro-Raman spectra of synthetic samples of the famous artists' pigments, chrome yellow and Maya blue, were investigated at various temperatures to determine their long-term stability with respect to dramatic changes in temperature. Synthetic chrome yellow was examined from −150°C to 500°C. Synthetic Maya blue was studied from ambient temperature up to ∼200°C, when the Raman signals became swamped by the strong fluorescence from the sepiolite clay in which the indigo dye was encapsulated. Both pigments proved to be extremely stable with respect to significant changes in temperature, which presumably accounts in part for their long-term use in artwork.

Full spectral XANES imaging using the Maia detector array as a new tool for the study of the alteration process of chrome yellow pigments in paintings by Vincent van Gogh

FS-XANES imaging using the Maia detector is proposed for studying chrome yellows alteration in Van Gogh artworks.

Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods. Part 5. Effects of nonoriginal surface coatings into the nature and distribution of chromium and sulfur species in chrome yellow paints.

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 the pigments. In this work, the results of Part 2 are extended and complemented with a new study aimed at deepening the knowledge of the nature and distribution of Cr and S species at the interface between the chrome yellow paint and the nonoriginal coating layer. For this purpose, three microsamples from two varnished paintings by Van Gogh and a waxed low relief by Gauguin (all originally uncoated) have been examined. Because nonoriginal coatings are often present in artwork by Van Gogh and contemporaries, the understanding of whether or not their application has influenced the morphological and/or physicochemical properties of the chrome yellow paint underneath is relevant in view of the conservation of these masterpieces. In all the samples studied, microscopic X-ray fluorescence (μ-XRF) and X-ray absorption near edge structure (μ-XANES) investigations showed that Cr(III)-based alteration products are present in the form of grains inside the coating (generally enriched of S species) and also homogeneously widespread at the paint surface. The distribution of Cr(III) species may be explained by the mechanical friction caused by the coating application by brush that picked up and redistributed the superficial Cr compounds, likely already present in the reduced state as result of the photodegradation process. The analysis of the XANES profiles allowed us to obtain new insights into the nature of the Cr(III) alteration products, that were identified as sulfate-, oxide-, organo-metal-, and chloride-based compounds. Building upon the knowledge acquired through the examination of original paint samples and from the investigation of aged model paints in the last Part 4 paper, in this study we aim to characterize a possible relation between the chemical composition of the coating and the chrome yellow degradation pathways by studying photochemically aged model samples covered with a dammar varnish contaminated with sulfide and sulfate salts. Cr speciation results did not show any evidence of the active role of the varnish and added S species on the reduction process of chrome yellows.

Raman study of different crystalline forms of PbCrO4 and PbCr1−xSxO4 solid solutions for the noninvasive identification of chrome yellows in paintings: a focus on works by Vincent van Gogh

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 different forms of this pigment is therefore relevant in order to extend knowledge on the corresponding degradation process that is observed on several original paintings. For this purpose, three paintings conserved at the Van Gogh Museum (Amsterdam) were analyzed using noninvasive Raman spectroscopy, while equivalent investigations employing bench‐top instrumentation were performed to obtain information from micro‐samples originating from these works of art. In each painting, the chrome yellow was identified either as monoclinic PbCrO4 or in the form of monoclinic PbCr1−xSxO4 (x < 0.25) or S‐rich orthorhombic PbCr1−xSxO4 (x ~ 0.5). Our ability to make this fairly subtle distinction is based on a Raman study of several oil paint model samples made up of monoclinic and/or orthorhombic crystalline forms of PbCrO4 and PbCr1−xSxO4 (0.1 ≤ × ≤ 0.8). These paints were studied using several excitation wavelengths (namely 785.0, 532.0, 514.5, and 488 nm). Because of the absence of the resonance Raman effect, which strongly enhances the chromate symmetric stretching band, and the absence of any laser‐induced photodecomposition, it is advantageous to acquire data at 785.0 nm. The band‐shape and the position of the chromate bending modes proved to be more sensitive to the solid solution composition and crystalline structure than the stretching modes and can be used as distinctive spectral markers to discriminate among the different chrome yellow forms that are present. Copyright © 2014 John Wiley & Sons, Ltd.

Spectroscopic analysis of artists’ pigments and materials used in southern Swedish painted wall hangings from the eighteenth and nineteenth centuries

The aim of this paper is to highlight various pigments found in 70 signed painted wall-hangings, so-called bonader, produced in southern Sweden during the eighteenth and nineteenth centuries. The analyses were performed using Fourier transform Raman (FT-Raman) spectroscopy and scanning electron microscopy–energy dispersive X-ray analyses, supplemented with microscopy and reconstructions of historic pigment references. The results indicate that inexpensive pigments such as chalk, woad, orpiment, ochres, red lead, and carbon black were used. Some synthetic pigments such as Prussian blue, emerald green, and chrome yellow were used for painted wall-hangings in the latter part of the period. Also some atypical artists’ painting materials such as a yellow lake made of curcuma, turmeric, and metallic lead foils were identified. FT-Raman spectra of a selection of pigments used for the wall-hangings are presented. The results from the study can be used for risk assessment for the deterioration of the wall-hangings in consideration of preventive and remedial conservation strategies. The art technological results, i.e. the painting materials found and the different painting techniques identified for each painter, can supplement previous stylistic attributions of unsigned and anonymous painted wall-hangings from southern Sweden.

A multi-analytical approach to the examination of nineteenth-century European wallpapers in Vasiq-Ansari House in Isfahan, Iran

In the nineteenth century, imported wallpapers covered interior walls of Persian palaces and mansions, of which Vasiq-Ansari House in Isfahan, Iran, exhibits very highly elaborated examples. In this study, micro-Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, ultraviolet–visible spectroscopy, and light microscopy were used to identify pigments and other materials used in the wallpapers of Vasiq-Ansari House. Results indicated that chrome yellow, artificial ultramarine blue, brass metallic leaf, an organic red dyestuff (probably cochineal), and a copper-based green were used as colourants in the wallpapers. Different shades of brown were achieved by mixing various combinations of red lead, carbon black, and calcium carbonate. The white calcium carbonate was also used as a ground layer, applied to a paper support composed of bast and softwood fibres. Based on knowledge of the materials used, these wallpapers are most probably manufactured from the mid- to late-nineteenth century.

Spectroscopic Characterization of a Contemporary Indian Miniature Painting

A case study on a contemporary Indian miniature was carried out through the application of different spectroscopic techniques. Painting support, pigments, and dyes were largely characterized by means of energy dispersive x-ray fluorescence and Raman microspectroscopy directly on the artwork. Regarding golden motifs and silvered areas, for which these techniques have not provided enough information, scanning electron microscopy coupled with energy dispersive x-ray spectroscopy was used as a complementary technique. The painting support was identified as the Bombyx mori silk. Among the colorant matters, several pigments were identified such as chrome yellow, lithopone, hematite, lamp black, mica-titania pearlescent pigment, and tin-based metallic silver, and dyes such as phthalocyanine blue and the recent synthetic pigment red PR9 naphthol AS. All this materials will provide evidence in the support of the contemporary production of the artwork for future studies.

Chrome yellow's darker side

Chrome yellow's darker side

The scientific investigation for the study and conservation of the wooden model of S. Maria della Consolazione's church (Todi, Italy)

Abstract The focus of this work is the wood polychrome model of the church of S. Maria della Consolazione in Todi, an artefact whose author and historical events are not completely known except a general reference to the construction period of the church (1508–1607 AD). In this study, original and additional materials were examined in order to provide a deeper understanding of the painting and assembly techniques, and a greater awareness of how well preserved the object is, as well as an analysis of previous preservation and conservation interventions. The samples from the painted surfaces were examined by means of micro-Raman spectroscopy, fourier transform infrared (FTIR) spectrometry and internal microstratigraphic analysis. Thin sections of the wood samples were examined under an optical transmission light microscope in order to identify the botanical species. The results shown in this paper suggest the possibility that the original painted layers are made of calcium carbonate white, red ochre and indigo and they were applied by protein binder without any ground layer. Some non-original pigments were found on the model surface like Prussian blue and chrome yellow. Concerning wood components, poplar was characterized both in the original and non-original parts of the model whereas pine species were detected only in the restoration elements.