Yellow Zinc Research Articles

Painting on the margins: investigating the pigments, media, and techniques of Séraphine Louis

The richly decorative and imaginative works by French artist Séraphine Louis (1864–1942) have long elicited fascination, and her working methods have often eluded art historians and conservators alike. Working in secret and outside established art circles, Séraphine employed materials such as natural resin varnishes and was said to have used household paints in addition to traditional artists' oil paints. In this study of six works in the collections of the Musée d'Art et d'Archéologie, Senlis (MAA), The Museum of Modern Art, New York (MoMA), and The Metropolitan Museum of Art, New York (MMA), attention was given to Séraphine's choice of colors and paints, in addition to identifying possible additions to or manipulations of painting media by the artist. Technical imaging was carried out using UVF to visualize the extent of Séraphine's use of natural resins. Analysis of the palette relied on XRF techniques and limited sampling for analysis by Raman and µ-FTIR spectroscopies. Overall, the following pigments were identified: lead white, zinc white, carbon-based black, red and brown ochres, umber, vermilion, alizarin lake, rhodamine B lake, Prussian blue, cobalt blue, ultramarine blue, chrome green, emerald green, viridian, cadmium yellow, and lead chromates, including chrome yellow deep and light, zinc yellow, and chrome orange. THM-Py-GCMS analysis of selected samples supported the documentary evidence of Séraphine's use of household oil paints; a single instance of a cellulose nitrate enamel paint was additionally determined by µ-FTIR. The chromatographic analysis also indicated a natural plant resin in her varnishes, probably dammar in combination with pine resin. Overall, this material investigation, accompanied by the art historical record, better reveals the techniques of an experimental painter whose works have come to epitomize French outsider artists of the early twentieth century.

A Spectroscopy-Based Multi-Analytical Approach for Studies in Conservation: Decorations in the Alexander Palace (Tsarskoye Selo)

We studied the painted decorations found during recent restoration work in the Alexander Palace in Tsarskoye Selo. Optical/laser spectroscopic methods were applied to obtain a characterization of the materials, pigments, and binders in use and, possibly, their degradation. We analyzed samples of the original Art Nouveau style decoration that was detached in 2019 during conservation work at the State Office of Emperor Nicholas II. A combination of Raman microscopy, infrared spectroscopy, and elemental analysis (obtained from the optical emission following laser plasma formation) allowed us to obtain detailed information on the materials used. The precious pigments of the artist’s green-blue palette and the binder used (drying oil) were identified. A mixture of blue (Prussian blue and ultramarine blue), white (lead white and barium white), and yellow (chrome yellow and zinc yellow) pigments determined the different blue hues used. The use of bronze paint in the dark blue area, which was identified as a brass powder applied with a drying oil as a binder, was also demonstrated.

BnaA03.ANS Identified by Metabolomics and RNA-seq Partly Played Irreplaceable Role in Pigmentation of Red Rapeseed (Brassica napus) Petal.

Colorful flowers of rapeseed (Brassica napus L.) have been a hotspot for researchers, but the underlying mechanisms of pigment formation still need to be clarified. In this study, two stages of unopened rapeseed petals with red, white, and yellow colors were selected to identify the metabolites and genes involved in red pigment formation. Metabolomic analysis showed that flavonoids enriched the most co-differentially accumulated metabolites among all categories, and showed higher accumulation in red petal rapeseed than in white and yellow petal ones. RNA-seq analysis showed that among co-differentially expressed genes involved in red pigment formation, genes involved in anthocyanin (belonging to flavonoids) biosynthesis pathway were largely regulated by ANS, DFR, and UF3GT. The expression of those genes was higher in red petals of rapeseed than in white and yellow petals ones as well. Results of RNA interference of BnaA03.ANS in red rapeseed altered petal colors from raspberry red to beige red and zinc yellow under different interference levels, with the contents of pelargonidin, cyanidin, lutein, neoxanthin, β-carotene, and lycopene significantly decreased. However, overexpression of BnaA03.ANS in yellow rapeseed petals did not change the color of yellow petals. This study confirmed the important function of flavonoids, especially anthocyanins on red pigment formation, and for the first time, identified the irreplaceable role of BnaA03.ANS on red-flowered rapeseed.

The chemistry behind the first Portuguese postage stamps (1853–1894). A non-destructive analytical and chemometric analysis of pigments, fillers and binders

The analysis of 28 specimens of some of the first Portuguese postage stamps, dated from 1853 to 1894, was undertaken with non-destructive techniques: X-Ray fluorescence (XRF), Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) and Ultraviolet–Visible Reflectance Spectroscopy (UV–Vis). Ink, paper and cancellation of the postage stamps were analysed, and the pigments, binders and fillers identified. Prussian blue was found present in all blue and also in green and brown specimens. Chrome and zinc yellow, lead sulphate and mars red were also found in other of the investigated postage stamps. Binders consist mostly of protein glue. Fillers such as calcite and kaolinite were found dominant. The presence of the latter served as an indicator for distinguishing between genuine and forged samples. UV–Vis spectra also proved useful for the same purpose. All the above information was processed and organized using chemometric techniques. These include mainly Hierarchical Cluster Analysis (HCA), for clustering stamps of similar composition, and Principal Component Analysis (PCA) for mapping the samples and identifying the more relevant variables. The latter are, in the paper, content of calcium, potassium, sulphur and silicon and, in the dye pigment area, of iron, zinc and lead content. The study introduces an approach in which, by combination of non-destructive multi analytical techniques with chemometric analysis, extensive information on different aspects of the composition of the studied postage stamps is provided, including that of paper and dyes.

The emergence of Liu Kang\u2019s new painting style (1950\u20131958): a multi-analytical approach for the study of the artist\u2019s painting materials and technique

Liu Kang (1911–2004) was renowned Singapore artist trained in Shanghai and Paris, and known for his contributions to the Nanyang style—an art movement practised by migrant Chinese painters in Singapore between the late 1940s to the 1960s. The style depicts aspects of the tropical way of life, synthetising the artistic traditions of the School of Paris and Chinese ink painting with remarkable stylistic innovations. The aim of this study was to characterise Liu Kang’s painting materials and technique by way of ten paintings from a significant period in his oeuvre, 1950–1958, during which his Nanyang style emerged. The selected artworks are from the National Gallery Singapore. A broad range of analytical techniques was employed to study the painting supports and paint layers. The results indicate the prevailing use of commercially prepared linen canvases with double-layered oil-based ground. Single- and triple-layered structures of the ground, as well as semi-absorbent ground, were used sporadically. The identified group of pigments partially overlaps with those already known from Liu Kang’s earlier practice and also incorporates some noteworthy peculiarities like manganese, cerulean and phthalocyanine blues, phthalocyanine green, zinc yellow, and naphthol red AS-D. Some of these newly identified pigments made a distinctive appearance in the individual artworks, but ultimately Liu Kang was not convinced about increasing their role in his painting practice of the 1950s as presented in this research. This study highlights the significance of drawing and photography as integral elements of his artistic process. It also delves into the artist’s different painting approaches and discusses their evolution, which culminated in the stylistic innovation that became Liu Kang’s signature for decades to come. The obtained data may assist art historians and conservators in authenticity and attribution studies, evaluating the condition of artworks and designing conservation strategies. Moreover, this study contributes to the growing body of knowledge about twentieth-century artists’ materials, which are characterised by the complex mixtures of inorganic and organic compounds. It also provides information about the availability of art materials in Singapore in the 1950s.

Analytical characterization of academic nude paintings from the Faculty of Fine Arts of the University of Lisbon

This study illustrates the analytical characterization of 20 academic nude paintings from the collection of the Faculty of Fine Arts of the University of Lisbon, made between 1899 and 1918. The study was performed by combining in situ non-invasive methods (infrared reflectography, radiography, and EDXRF) and laboratory microanalytical techniques (micro-Raman, micro-FTIR, and SEM-EDS). Infrared reflectography revealed underdrawings, underpaintings, painting style, and execution methods. Analytical techniques allowed the identification of painting materials, such as gypsum, lead white, barium white, zinc white, yellow ochre, chrome yellow, zinc yellow, red ochre, vermilion, ultramarine blue, hematite, Mars red, and lamp black. This study provides valuable information on the academic nude paintings’ palette and its artistic production technique. Finally, it intends to continue a systematic analytical study of the Faculty of Fine Arts’ collection, allowing the characterization of Master painters, their students, and other authors.

Complex Relationships: A Materials Study of Édouard Vuillard’s Interior, Mother and Sister of the Artist

Édouard Vuillard (1868–1949) is well known for his small atmospheric paintings, often portraying his own home and family as the subject matter. Interior, Mother and Sister of the Artist (1893) underwent at least one restoration treatment before being acquired by the Museum of Modern Art (MoMA) in 1934. The painting was treated again in 1954, but no analysis was carried out to understand the artist’s methods and materials at that time. To better understand the choices of Vuillard in Interior, Mother and Sister of the Artist, a comprehensive suite of imaging and spectroscopic analyses was undertaken, including: XRR, UVF and IRR Photography, XRF, Raman spectroscopy and SERS, and µ-FTIR. Statistical analysis on the XRF data using MCR-ALS further revealed some of the intricacies of Vuillard’s technique and color choices, where a large number of pigments were used in designing this intimate composition, including lead white, zinc white, bone black, ochre, umber, vermilion, Geranium lake, red lead, ultramarine, Prussian blue, chrome yellow, chrome orange, zinc yellow, strontium yellow, cadmium yellow, and a chromium oxide green.

Complementary Use of Raman and µ-XRF Spectroscopy for Non-destructive Characterization of an Oil Painting by Turkish Painter İbrahim Çallı

The aim of the present work was to invastigate the pigments used in oil painting “in the park” created in the first half of the 20th century, by Turkish painter and academician İbrahim Çallı (1882-1960). The non-destructive analyses were performed with a combination of µ-XRF and Raman Microscopy. Obtained results revealed following pigments on the investigated painting: zinc white (ZnO), zinc yellow (K2O·4ZnCrO4·3H2O), chrome yellow (PbCrO4), strontium yellow (SrCrO4), ultramarine (Na7Al6Si6O24S3), prussian blue (Fe7C18N18), hematite (α-Fe2O3), cadmium red (CdSe), barite (BaSO4) and carbon black. There is a great lack of knowledge about the materials used in Turkish painting and this non-destructive study provides the first systematic investigation into Çallı's palette.

Study of Hillock and Zinc Whisker Evolution in Five Different Cable Tray Coatings

The main objective of this work is the study of the hillock and zinc whisker evolution of five different commercial zinc coatings applied on the same base steel wires of the patented EASYCONNECT system cable trays manufactured by VALDINOX Ltd.: white zinc alkaline electrolyte, yellow zinc trivalent electrolyte, acid zinc electrolyte, hot dip galvanized, and zinc nickel coating. The limited literature on the subject is summarized, and then the coating thickness, chemical composition, hardness and surface rugosity are characterized. The hillock and whisker density evolution are evaluated over a period of 12 months, considering the presence of compression bending stresses. It is concluded that the white alkaline and yellow trivalent coatings are the most affected, while the zinc-nickel shows the best behavior with no presence of whiskers; the acid zinc electrolyte also shows good results despite the delayed appearance of whiskers from the ninth month; the hot-dip galvanized coating does not show any presence of zinc whiskers or hillocks.

Formation of zinc oxalate from zinc white in various oil binding media: the influence of atmospheric carbon dioxide by reaction with 13CO2

The formation of metal oxalates in paintings has recently gained a great deal of interest within the field of heritage science as several types of oxalate compounds have been identified in oil paintings. The present work investigates the formation of metal oxalates in linseed oil in the presence of the artists’ pigments zinc white, calcite, lead white, zinc yellow, chrome yellow, cadmium yellow, cobalt violet, and verdigris. The oil paint films were artificially photo-aged by exposure to UVA light at low and high relative humidity, and afterwards analysed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The results showed that, compared to the other pigments investigated, zinc white is especially prone to metal oxalate formation and that high humidity is a crucial factor in this process. Consequently, the reactivity and photo-aging of ZnO in various oil binding media was investigated further under simulated solar radiation and at high relative humidity levels. ATR-FTIR showed that zinc oxalate is formed in all oil binding media while X-ray powder diffraction (PXRD) revealed it was mainly present in an amorphous state. To examine whether atmospheric CO2(g) has any influence on the formation of zinc oxalate, experiments with isotopically enriched 13CO2(g) were performed. Based on ATR-FTIR measurements, neither Zn13C2O4 nor Zn13CO3 were formed which suggests that the carbon source for the oxalate formation is most likely the paint itself (and its oil component) and not the surrounding atmosphere.

Single crystal X-ray structure of the artists' pigment zinc yellow

The artists' pigment zinc yellow is in general described as a complex potassium zinc chromate with the empirical formula 4ZnCrO4·K2O·3H2O. Even though the pigment has been in use since the second half of the 19th century also in large-scale industrial applications, the exact structure had hitherto been unknown. In this work, zinc yellow was synthesised by precipitation from an aqueous solution of zinc nitrate and potassium chromate under both neutral and basic conditions, and the products were compared with the pigment used in industrial paints. Analyses by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and powder X-ray diffraction (PXRD), showed that the synthesised products and the industrial pigment were identical. Single-crystal X-ray crystallography determined the structure of zinc yellow as KZn2(CrO4)2(H2O)(OH) or as KZn2(CrO4)2(H3O2) emphasizing the μ-H3O2− moiety. Notably, the zinc yellow is isostructural to the recently structurally characterized cadmium analog and both belong to the natrochalcite structure type.

Characterization of Sorolla's gouache pigments by means of spectroscopic techniques

Abstract This paper presents the characterization of the Joaquin Sorolla's gouache sketches for the oil on canvas series “Vision of Spain” commissioned by A. M. Huntington to decorate the library of the Hispanic Society of America in New York. The analyses were focused on the identification of the elemental composition of the gouache pigments by means of portable EDXRF spectrometry in a non-destructive mode. Additionally, SEM-EDX and FTIR analyses of a selected set of micro-samples were carried out to identify completely the pigments, the paint technique and the binding media. The obtained results have confirmed the identification of lead and zinc white, vermillion, earth pigments, ochre, zinc yellow, chrome yellow, ultramarine, Prussian blue, chromium based and copper–arsenic based green pigments, bone black and carbon based black pigments, and the use of gum arabic as binding media in the gouache pigments.

Analytical characterization of academic nude paintings by José Veloso Salgado

This case study illustrates the analytical characterization of 12 academic nude paintings by Veloso Salgado, made between 1883 and 1893. The study was done with in situ methods (infrared reflectography and EDXRF) and benchtop equipment (Raman and FTIR microscopes and SEM-EDS). Infrared reflectography revealed underdrawings, painting style, execution method and retouched/restored areas. Analytical techniques allowed the identification of gypsum, lead white, barium white, zinc white, yellow ochre, chrome yellow, zinc yellow, vermilion, synthetic ultramarine blue, cerulean blue, Prussian blue, viridian, green earth, Paris green, red ochre, raw umber and lamp black. These results provide valuable information on Salgado’s palette and his artistic production technique and allow the distinction between palettes used in Lisbon and Paris and consequently, technical interchanges between both Academies. Finally, this study intends to start a systematic analytical study of the Faculty of Fine Arts’ collection, allowing the characterization of many other authors and their influences for the development of painting methodology in this Academy.

Anticorrosion protection of strength bolts

Corrosion damage may, from the technical point of view, cause changes in mechanical and physical characteristics in particular, at the same time it may also cause changes in surface geometry. These aspects are likely to manifest themselves in all steel parts. The presented study looks at corrosion protection in bolts and bolt connections protected by metal coating based on zinc.Four different types of passivation, easily accessible on the Czech market, have been selected for this experiment. They are as follows: first, galvanic plating using white zinc; second, galvanic plating using yellow zinc; third, hot dip galvanizing; fourth, specific type of plating using the technology Dacromet 500 LC. In order to compare the given parameters there have been selected a unified M bolt size of 8 × 30 mm. The experimental part of this study can be further divided into two phases. The initial phase puts stress on the exact specification of the protection layer, namely, the analysis and establishment of the elemental compositon contained in the given coating, its microhardness, weight and thickness. The second phase of the experiment analyses the results of tests according to the norm ČSN ISO 9227 (Salt Fog Test) and ČSN ISO 6988 (Sulphur Dioxide Test). With the tests we have concentrated on the initial stages of corrosion degradation and its overall process.

Raman Analysis on 18th Century Painted Wooden Statues

A micro-Raman investigation on four wooden polychrome sculptures of Jan Geernaert (1704-1777), a Flemish sculptor who worked in Italy in the 18th century, is presented. The statues, representing the Holy Virgin Mary, with the infant Jesus in three of them, were created in the period 1750-1770 and are all made by poplar wood. The purpose of the micro-Raman investigations was to identify the original pigments used in 18th century, after later repainting interventions. In all statues, wood is covered by a groundwork, made by gypsum and animal glue. All pigments were identified, both in the original pictorial cover or in later repainted layers. Pigments were spread on a white lead layer (the so called imprimitura). Attention was particularly focused on the blue colours of the Holy Virgin mantle. In the external repainted layers, Prussian blue (Iron(II,III) hexacyanoferrate(II,III)) was found, together with ultramarine blue, a synthetic pigment, alternative to natural precious lapis lazuli, accessible on or after 1828. In one case, phthalocyanine blue is found, confirming a recent (later than 1930-35) restoration. The original skin colours are obtained by white lead and cinnabar (HgS), while the repainted layers are made by mixing chrome yellow (PbCrO4, synthesized in 1809), zinc yellow (ZnCrO4, 1809), red lead (Pb3O4), ultramarine blue, cinnabar, hematite (Fe2O3), goethite (-FeOOH), calcite (CaCO3) and white lead.

Floral structure and pollen morphology of two zinc violets (Viola lutea ssp. calaminaria and V. lutea ssp. westfalica) indicate their taxonomic affinity to Viola lutea

Two zinc violets, the yellow form of the Aachen–Liège area and the blue morph of Blankenrode in western Westphalia, have very restricted occurrence on heavy metal waste heaps. Their taxonomic affinities have not been finally resolved. The flower micromorphological analysis presented here indicates that both zinc violets are closely related to the alpine Viola lutea, in line with our earlier published molecular data, but not with the conclusions of other authors. The zinc violets are classed at the rank of subspecies as V. lutea: ssp. calaminaria for the yellow zinc violet and ssp. westfalica for its blue counterpart. Although the violets examined (V. lutea, V. lutea ssp. calaminaria, V. lutea ssp. westfalica) are closely related, there is no evidence that V. lutea ssp. westfalica is a descendent of V. tricolor. Here we provide the most detailed information on generative organ structure in the four violets studied.

Violets of the section Melanium, their colonization by arbuscular mycorrhizal fungi and their occurrence on heavy metal heaps

Violets of the sections Melanium were examined for their colonization by arbuscular mycorrhizal fungi (AMF). Heartsease ( Viola tricolor) from several heavy metal soils was AMF-positive at many sites but not at extreme biomes. The zinc violets Viola lutea ssp. westfalica (blue zinc violet) and ssp. calaminaria (yellow zinc violet) were always AMF-positive on heavy metal soils as their natural habitats. As shown for the blue form, zinc violets germinate independently of AMF and can be grown in non-polluted garden soils. Thus the zinc violets are obligatorily neither mycotrophs nor metalophytes. The alpine V. lutea, likely ancestor of the zinc violets, was at best poorly colonized by AMF. As determined by atomic absorption spectrometry, the contents of Zn and Pb were lower in AMF colonized plants than in the heavy metal soils from where the samples had been taken. AMF might prevent the uptake of toxic levels of heavy metals into the plant organs. Dithizone staining indicated a differential deposition of heavy metals in tissues of heartsease. Leaf hairs were particularly rich in heavy metals, indicating that part of the excess of heavy metals is sequestered into these cells.

The darkening of zinc yellow: XANES speciation of chromium in artist's paints after light and chemical exposures

The color darkening of selected brushstrokes of the masterpiece A Sunday on La Grande Jatte – 1884 (by Georges Seurat) has been attributed to the alteration of the chromate pigment zinc yellow. The pigment originally displays a bright greenish-yellow color but may undergo, after aging, darkening to a dull, ocher tone. We used XANES to probe the oxidation state of Cr on paint reconstructions, and show that color changes are associated with the reduction of Cr(VI) to Cr(III). Paint mixtures containing the pigment and linseed oil to mimic mixtures used in La Grande Jatte were subjected to artificial aging in the presence of light, SO2, and variable air humidity—50 and 90% relative humidity. High relative humidity led to the largest degree of Cr(VI) reduction whereas low relative humidity promoted light-induced alterations. These results are corroborated by visible reflectance measurements on the same laboratory samples and contribute to a better understanding of the chemical reactivity of chromate pigments, which are present in many historical works of art.

Electron energy loss spectroscopy elucidates the elusive darkening of zinc potassium chromate in Georges Seurat’s A Sunday on La Grande Jatte—1884

The color darkening of selected brushstrokes of Georges Seurat's A Sunday on La Grande Jatte--1884 was noted as early as 1892. Artificial aging of model systems containing zinc yellow (K(2)O·4ZnCrO(4)·3H(2)O) mixed with linseed oil successfully replicated the phenomena observed on La Grande Jatte. Electron energy loss spectroscopy measurements performed on the uppermost few microns of thin sections of the paint layers (obtained with focused ion beam milling) determined that samples which turned olive green (aged at 90% RH, with SO(2) and light) contain mostly the altered species Cr(III) and that the ochre-yellow coloration of specimens aged at 50% RH with SO(2) and light is due to the presence of dichromate ions (Cr (VI)). The altered species are only present in the first few microns of paint and are likely poorly crystalline, so that they eluded other types of bulk and surface measurements, but they create a substantial color alteration at the surface of the paint films. A similar phenomenon was confirmed on a sample from La Grande Jatte, where Cr(III) and Cr(VI) dichromate ions were detected in the ochre-colored, altered brushstrokes of zinc yellow. Laboratory simulations demonstrated that the equilibrium between chromate and dichromate ions is reversible within the paint film and that the orange dichromate ions can be transformed back into bright yellow chromates by exposure to highly alkaline gases.

The palette of the Macchia Italian artist Giovanni Fattori in the second half of the xixth century

Giovanni Fattori (Livorno 1825–Firenze 1908) is the most representative artist of the Macchiaioli's current, an early group of Italian plein-air artists, whose work anticipates, in the xixth century, that of their younger contemporaries, the French Impressionists. The study, performed by a multidisciplinary team made up of scientists and conservators, presents the results of the scientific characterization carried out on a group of 10 paintings made by Fattori between 1854 and 1893 and shows the way he used complex mixtures of a large variety of traditional and synthetic pigments, ranging from lead white, found pure and also extended with calcium carbonate, natural barite and gypsum to zinc white, from red ochre to cinnabar and vermilion, from yellow ochre and Naples yellow to chrome yellow, cadmium yellow and zinc yellow, combined with many other ones reported in details. This paper highlights the evolution of his painting technique during a time of great technological and social innovations and puts forward some hypothesis on his awareness about manufactured pigments, i.e. tube paints recently introduced into the artists’ circles. The wide range of pigments and their different quality among the same synthetic products suggest that the artist used all the available materials, and that picking out the pigments he retained the early xixth century artists techniques, such as the use of mineral earths and Prussian blue, similarly to his contemporary Italian artists Federico Zandomeneghi and Telemaco Signorini, but he also experimented new and peculiar pigment mixtures in the making of “colored darks” and an innovative use of the grounds in the final composition, that are also distinctive features of the French Impressionists. This work is aimed at contributing to overcome the lack of a comprehensive overview on the widespread historical and scientific data collected up to now on the Italian paintings in the xixth century, which has been severely underestimated with respect to previous art movements.