Cadmium Yellow Research Articles

소목, 치자, 쑥으로부터 추출된 천연염료의 색도분석

환경 친화적이고 질병을 유발시키지 않은 천연색소의 사용이 증가함에 따라 천연색소를 추출하는 다양한 방법이 연구되고 있다. 본 연구에서는 천연염료인 brazilein, crocin, chlorophyll을 포함하고 있는 식물성 원료인 소목, 치자, 쑥을 대상으로 천연염료를 추출하였다. 추출용매의 pH와 추출시간을 변수로 추출된 천연염료의 적색, 황색, 녹색계열의 목표색을 설정하고 추출된 천연염료의 명도와 색의 좌표(L, a, b)의 정량적 수치로부터 색도분석을 수행하였다. 소목의 적색소인 brazilein과 치자의 황색소인 crocin의 경우 목표색인 카드뮴 레드와 카드뮴 옐로에 근접한 색상을 추출할 수 있었다. 추출시간 20 min을 기준으로 brazilein의 경우 pH 12, crocin의 경우 pH 9에서 색차를 나타내는 <TEX>${\Delta}E^*$</TEX>가 각각 18.2와 18.4로 목표색과 유사한 색의 색소가 추출되었다. 그러나 쑥의 녹색색소인 chlorophyll의 경우 목표색인 크롬 그린과는 차이를 보였다. Extracting natural dyes have been widely studied since the needs of eco-friendly and non-toxic natural dyes increased. In this paper, the natural dyes were extracted from sappan wood, gardenia, and mugwort containing brazilein, crocin, and chlorophyll process. After the extraction with variables of pH of solvent and reaction time, the chromaticity of extracted natural dyes was analyzed using quantitative values from brightness and color coordinate (L, a, b) based on the target colors of red, yellow and green. For the case of brazilein and crocin, the cadmium red and cadmium yellow, respectively were extracted. In the case of sappan wood and gardenia, the red pigment under pH 12 (<TEX>${\Delta}$</TEX> = 18.2) and the yellow pigment at pH 9 (<TEX>${\Delta}$</TEX> = 18.4) were extracted respectively. However, the color of extracted chlorophyll from mugwort was different from the target chrome green.

How Red is Cadmium Red?

Interest in the colour reproduction of artworks and artefacts is gaining more significance, as it is now recognised that some artefacts are too delicate to be exhibited and some important landmarks are no longer around due to damage by war or climate change. This brings a need for further research in how to obtain and transmit accurate colour information for the reproduction of texture, three-D artefacts, and the reconstruction of lost colour and heritage colours. There is a need to regain an understanding of the cultural implications of colour and an emerging area of discussion in relation to resilience. Cadmium red refers to a chemical colour that has been used and loved by artists for centuries, yet this extremely toxic colour is under threat. Cadmium is used in batteries, for electroplating, jewellery, footwear, and of course, paint. The restrictions on cadmium, like chromium or mercury, are obviously necessary for us and the environment, but have posed a problem for many industries reliant on these materials. A key challenge has been the costs involved in remanufacture using alternative materials. In the context of new legislation relating to heavy metals such as cadmium, ink manufacturers, for example, are now forced to reconsider the content of their inks and replace toxic pigments and materials with more environmentally safer versions. Yet despite the change in the constituents of the paint, the naming traditions that are so closely associated with art history are still used by paint manufacturers. The romance of Cadmium red remains even though distant from its traditional and cultural origins. Many the pigment colours of the 15th and 16th centuries are far removed from the dyes and acrylics of the 21st century, but the naming of these new equivalents uses the terminology originally generated from the materials or associations of their forebears. The question remains: what impact does this have for the colour restorer or colour conservator? How might conventions and standards in colour naming for the paint manufacturer or the domestic paint industry be developed? We ask how red is the Cadmium red that is now available? Based on an inspection of traditional and contemporary paint charts, many variations of hues associated with Cadmium red can be seen. The range in saturation and hue will be explored. We also look closely at how a red hue that is loosely associated to a heritage name is used in the 21st century. Albeit seeming a somewhat narrow question, it is predicated on a much larger enquiry that looks at the implications arising from a situation in which colour manifest in material form is an increasingly rare commodity. This has occurred due to the rise if digital fabrication technologies, redistributed manufacturing, applications for mimicking paint colours and brush strokes, and 2.5D printing. The challenge of the sustainability of using some colour sources and their resilience has also constrained colour use. In an apocryphal story by Jasper Fford about a world where colour is indeed synthetic (Shades of Grey: The Road to High Saffron), green is piped to the grass to colour it green, and colour is collected as a rare commodity. The question here is: what is the future of colour – as computational versions or facsimiles of chemical colours or colour that is salvaged? In a world of seemingly plenty, our resources are dwindling, yet colour remains a vital resource for our economy, society and culture. Our diversity of geography means that environmental colour, the colour of the stuff with which we build our dwellings, and those with which we describe our built and natural environments, have imbued our culture with a wide sensibility in respect of how colour works in everyday contemporary life, but we need to understand how we manage its integrity and our language for describing this resource in the light of new technology and care for the lived environment.

Chromium speciation methods and infrared spectroscopy for studying the chemical reactivity of lead chromate-based pigments in oil medium

Environmental factors, such as light, humidity and temperature are triggering agents for the alteration of organic and/or inorganic constituents of oil paintings. The oxidation of the organic material is favored by increasing of relative humidity and temperature, whereas processes involving changes of the oxidation states of a number of inorganic pigments (e.g., vermilion, cadmium yellows, zinc yellows, chrome yellows) are mainly activated by light-exposure.In view of the optimization of the long-term conservation and restoration strategies of paintings it is of relevant interest to establish the consequences of thermal parameters (temperature and relative humidity) on the chemical/photochemical-reactivity and the nature of the alteration products of light sensitive-pigments in oil medium.To this aim here we propose a multi-method analytical approach based on the combination of diffuse reflectance UV–Vis, FTIR, synchrotron radiation (SR)-based micro X-ray fluorescence (μ-XRF)/micro-X-ray absorption near edge structure (XANES) and electron paramagnetic resonance (EPR) spectroscopies for studying the effects of different relative humidity conditions before and after light exposure on the reactivity of a series of lead chromate-based pigments [such as PbCrO4∙PbO (monoclinic), PbCrO4 (monoclinic) and PbCr0.2S0.8O4 (orthorhombic)] in an oil medium. The investigation of paint models was also compared to that of a late 19th century historical orthorhombic PbCr0.4S0.6O4 oil paint.Diffuse reflectance UV–Vis and FTIR spectroscopies were used to obtain information associated with chromatic changes and the formation of organo-metal degradation products at the paint surface. SR-based Cr K-edge μ-XANES/μ-XRF mapping analysis and EPR spectroscopy were employed in a complementary fashion to determine the amount, nature and distribution of Cr(III) and Cr(V)-based alteration compounds within the paints with micrometric spatial resolution.Under the employed thermal aging conditions, lead(II)-carboxylates and reduced Cr-compounds (in abundance of up to about 35% at the surface) have been identified in the lead chromate-based paints. The tendency of chromates to become reduced increased with increasing moisture levels and was favored for the orthorhombic PbCr0.2S0.8O4 compounds. The redox process gave rise to the formation of Cr(V)-species in relative amount much higher than that was formed in the equivalent paint which was exposed only to light.After light-exposure of the thermally aged paints, compounds ascribable to the oxidation of the organic binder were detected for all the types of pigments. Nevertheless, the previous thermal treatment increased the tendency toward photo-reduction of only the PbCr0.2S0.8O4 pigment. For this light-sensitive compound, the thickness variation of the reduced Cr-rich (ca. 70%) photo-alteration layer with moisture levels could be ascribed to a surface passivation phenomenon that had already occurred before photochemical aging.

Accelerated UV ageing studies of acrylic, alkyd, and polyvinyl acetate paints: Influence of inorganic pigments

The stability of two types of acrylic binding media, alkyd and polyvinyl acetate (PVAc), four widely used synthetic binders in modern and contemporary art, to UV light also including the UV-B range (315–280nm, middle UV) for simulating sunlight outdoor conditions was studied and compared by double-shot and single-shot Py-GC/MS, FTIR-ATR, and colour measurements. Thermally assisted hydrolysis and methylation (THM-GC/MS) analyses were used for the alkyd. Additionally, the influence of inorganic pigments on the photo-oxidative stability of the binding media was also considered. For this purpose, the binders in their pure form as well as mixed with eight different inorganic pigments (titanium white—anatase and rutile, cadmium yellow, cadmium red, hydrated chromium oxide green, ultramarine blue, raw umber Cyprus, and ivory black) were exposed to the accelerating artificial UV ageing for different periods of time and analysed before and after UV exposure. After UV ageing, the double-shot Py-GC/MS detected the effect of photo-oxidative processes of the binders in a much more detailed way than by the single shot. For instance, photo-oxidation of the acrylics resulted in a production of oligomers even during the thermal desorption step of double-shot Py-GC/MS and in a decrease of the EA and nBA main monomers in the pyrolysis second step. Contrarily, the aged alkyd samples were mostly characterised by a decrease of unsaturated fatty acids and especially by the increase of free ortho-phtalic acid detected by double-shot Py-GC/MS and THM-GC/MS, which is also reflected in the FTIR-ATR results. On the other hand, an increase of free acetic acid was observed for the aged polyvinyl acetate by double-shot Py-GC/MS. Colour measurements recorded a greater sensitivity of the alkyd paints, shown by to the bigger shift of L*, a*, and b* coordinates and change of E* values. Of additional interest was the higher sensitivity to the UV light for synthetic binding media in combination with pigments.

The characterization of canvas painting by the Serbian artist Milo Milunović using X-ray fluorescence, micro-Raman and FTIR spectroscopy

Abstract A canvas painting by Milo Milunovic “The Inspiration of the poet” was studied by energy dispersive X-Ray fluorescence (EDXRF), micro-Raman and Fourier transform infrared (FTIR) spectroscopy in order to identify materials used by the artist and his painting technique. Study is perfomed combining in situ non-destructive method with the preparation and study of cross-section samples and raw fragments of the samples. Milo Milunovic, an eminent painter from Balkan region, made a copy of the Nicolas Poussin's original painting in Louvre in 1926/27. Obtained results revealed following pigments on the investigated canvas painting: vermilion, minium, cobalt blue, ultramarine, lead white, zinc white, cadmium yellow, chrome-based green pigment and several earth pigments – red and yellow ocher, green earth and umber. Ground layer was made of lead white mixed with calcium carbonate.

2D X-ray and FTIR micro-analysis of the degradation of cadmium yellow pigment in paintings of Henri Matisse

The chemical and physical alterations of cadmium yellow (CdS) paints in Henri Matisse’s The Joy of Life (1905–1906, The Barnes Foundation) have been recognized since 2006, when a survey by portable X-ray fluorescence identified this pigment in all altered regions of the monumental painting. This alteration is visible as fading, discoloration, chalking, flaking, and spalling of several regions of light to medium yellow paint. Since that time, synchrotron radiation-based techniques including elemental and spectroscopic imaging, as well as X-ray scattering have been employed to locate and identify the alteration products observed in this and related works by Henri Matisse. This information is necessary to formulate one or multiple mechanisms for degradation of Matisse’s paints from this period, and thus ensure proper environmental conditions for the storage and the display of his works. This paper focuses on 2D full-field X-ray Near Edge Structure imaging, 2D micro-X-ray Diffraction, X-ray Fluorescence, and Fourier Transform Infra-red imaging of the altered paint layers to address one of the long-standing questions about cadmium yellow alteration—the roles of cadmium carbonates and cadmium sulphates found in the altered paint layers. These compounds have often been assumed to be photo-oxidation products, but could also be residual starting reagents from an indirect wet process synthesis of CdS. The data presented here allow identifying and mapping the location of cadmium carbonates, cadmium chlorides, cadmium oxalates, cadmium sulphates, and cadmium sulphides in thin sections of altered cadmium yellow paints from The Joy of Life and Matisse’s Flower Piece (1906, The Barnes Foundation). Distribution of various cadmium compounds confirms that cadmium carbonates and sulphates are photo-degradation products in The Joy of Life, whereas in Flower Piece, cadmium carbonates appear to have been a [(partially) unreacted] starting reagent for the yellow paint, a role previously suggested in other altered yellow paints.

Evaluation of the Potential of Cadmium and Dyes Removal by Chitosan Obtained from Zygomycetes

Background: Treatment process for heavy metal and dye removal is a worrying factor in environmental health because it can contribute to the formation of new contaminants. Objectives: To obtain and use chitosan from Zygomycetes for removal process of heavy metal (cadmium) and azodyes (Reactive Black and Remazol Red). Methods: Chitosan was obtained by Rhizopus arrhizus UCP 402 and Mucor javanicus UCP 69 following the described method of Synowiecki and Al-Khateeb (1997) and submitted to removal tests for 18 h, with different concentrations of Cadmium (0.5-4 mM), Reactive Black (B) and Remazol Red (1-1000 mg/L) in orbital shaker under 150 rpm at 28°C. Then, the samples were submitted to spectrophotometry and chitosan exposed to the contaminants were submitted to electronic microscopy analysis. Results: The efficiency of cadmium removal by Rhizopus arrhizus chitosan showed data of 92% (0.5 mM), 92.8% (1 mM), 75.9% (2 mM), 54% (3 mM) and 54.5% (4 mM) at pH 6.0. The efficiency of dyes removal by Mucor javanicus chitosan was about 100% (1 mg/L), 100% (10 mg/L), 100% (50 mg/L), 98% (100 mg/L), 55% (1000 mg/L) for Reactive Black (B) and 100% (1 mg/L), 100% (10 mg/L), 100% (50 mg/L), 98% (100 mg/L), 59% (1000 mg/L) for Remazol Red. Conclusion: Chitosan obtained by the strains was capable of removing cadmium and the reactive dyes: Reactive Black (B) and Remazol Red in all conditions tested.

Raman spectroscopic signatures of the yellow and ochre paints from artist palette of J. Matejko (1838–1893)

The Raman and complementary spectroscopic analyses were performed using the exceptional possibility of research on the XIX c. original paint materials of the artist palette of J. Matejko stored in the National Museum in Cracow. The yellow and ochre-based paints characteristic for Matejko’s workshop and selected from the ensemble of 273 labelled tubes (brand of R. Ainé/Paris) supplied during the period of 1880–1893 were investigated. Highly specific Raman spectra were obtained for paints containing mixtures of the Zn- and Sn-modified Pb–Sb pigment, and also for the ochre-based ones. A clear pigment discrimination of the mixture of cadmium yellow (CdS), cinnabar (HgS) and lead white (2PbCO3⋅Pb(OH)2) was possible by means of Raman data collected under different excitations at 514nm and 785nm. It was shown that the Raman spectra complemented by the XRF, SEM–EDX and in some cases also by the LIPS and FTIR data ensure reliable pigment identification in multi-component paints containing secondary species and impurities. The reported spectral signatures will be used for non-destructive investigation of the collection of about 300 oil paintings of J. Matejko. In view of the comparative research on polish painting which point out that richness of modified Naples yellows clearly distinguish Matejko’s artworks from other ones painted in the period of 1850–1883, the Raman data of these paints can provide support in the authentication studies.

Electrochemical photodegradation study of semiconductor pigments: influence of environmental parameters.

Chemical transformations in paintings often induce discolorations, disturbing the appearance of the image. For an appropriate conservation of such valuable and irreplaceable heritage objects, it is important to have a good know-how on the degradation processes of the (historical) materials: which pigments have been discolored, what are the responsible processes, and which (environmental) conditions have the highest impact on the pigment degradation and should be mitigated. Pigment degradation is already widely studied, either by analyzing historical samples or by accelerated weathering experiments on dummies. However, in historic samples several processes may have taken place, increasing the complexity of the current state, while aging experiments are time-consuming due to the often extended aging period. An alternative method is proposed for a fast monitoring of degradation processes of semiconductor pigments, using an electrochemical setup mimicking the real environment and allowing the identification of harmful environmental parameters for each pigment. Examples are given for the pigments cadmium yellow (CdS) and vermilion (α-HgS).

Metals in Lip Products - A Cause for Concern?

Metals in Lip Products - A Cause for Concern?

X-ray fluorescence and imaging analyses of paintings by the Brazilian artist Oscar Pereira Da Silva

Non-destructive analyses, such as EDXRF (Energy-Dispersive X-Ray Fluorescence) spectroscopy, and imaging were used to characterize easel paintings. The analyzed objects are from the collection of the Pinacoteca do Estado de São Paulo. EDXRF results allowed us to identify the chemical elements present in the pigments, showing the use of many Fe-based pigments, modern pigments, such as cobalt blue and cadmium yellow, as well as white pigments containing lead and zinc used by the artist in different layers. Imaging analysis was useful to identify the state of conservation, the localization of old and new restorations and also to detect and unveil the underlying drawings revealing the artist's creative processes.

SR-FTIR imaging of the altered cadmium sulfide yellow paints in Henri Matisse's Le Bonheur de vivre (1905–6) – examination of visually distinct degradation regions

SR-FTIR imaging has been used to map the mid-IR active photo-degradation phases in two thin sections of cadmium yellow paint removed from Henri Matisse's Le Bonheur de vivre (1905-1906, The Barnes Foundation). These samples represent both the darkened cadmium yellow foliage in the upper left of the work and the lightened cadmium yellow field beneath the central reclining figures. The altered cadmium yellow paints from both regions were found to contain cadmium carbonate (CdCO3), cadmium sulphate (CdSO4), and cadmium oxalate (CdC2O4). Each of these phases was imaged to determine their positions as a function of depth, with the aim of better understanding the role of each phase in the degradation mechanism. This speciation mapping is critical because cadmium oxalate was used in this period as an additive in cadmium yellow light. In addition, cadmium carbonate and cadmium sulphate were synthesis starting materials for cadmium yellow, and so their distribution throughout the paint layer can provide an indication of their roles. It was established that cadmium oxalate is localized at the surface of the paint layer, cadmium carbonate is found deeper in the layer but still enriched at the surface, and cadmium sulphate is distributed throughout the layer. This distribution, along with the chloride content of the paint suggesting a cadmium chloride starting material, is consistent with an alteration mechanism in which the cadmium sulphide is oxidized to sulphate and this is then converted to carbonate and oxalate. The relative solubilities of the three photo-degradation products are also relevant to their locations in the paint film.

Materials applied in Bernardo Martorell’s painting analysed by portable XRF

Bernardo Martorell was a leading artist of the 15th century in Catalonia . His panel painting the Ascension of the Virgin is one of the oldest in the collection of Fine Arts Museum of Seville. This is why it was chosen for the analysis among several other panels which form part of a bigger project between the Museum and the National Centre of Accelerators. The research work is dedicated to the characterization of materials applied in the Spanish paintings in the 15th and 16th centuries. The painting was studied by non-destructive techniques (UV light and a portable X-Ray fluorescence) to obtain information on materials applied and possible later interventions. The results showed that the original pigments applied are common for that period of time: lead white (Pb) yellow and red ochres (Fe), massicot, (Pb), umbra (Mn, Fe), vermillion (Hg), azurite (Cu) and a copper based green pigment (Cu). The thin layer of gold, confirmed by Au peaks, is applied over the surface, on top of a red bole layer. Some black areas over the gilded surface contain Ag. Retouches contain Ti, Zn, Cr and Cd that confirm the use of modern pigments, such as titanium-zinc white, chrome green or cadmium red.

The photodegradation of cadmium yellow paints in Henri Matisse’s Le Bonheur de vivre (1905–1906)

Evidence for the alteration of the yellow paints in Henri Matisse’s Le Bonheur de vivre (1905–1906, The Barnes Foundation) has been observed since the 1990s. The changes in this iconic work of Matisse’s Fauvist period include lightening, darkening, and flaking of the yellow paints. Handheld X-ray fluorescence (XRF) and multispectral imaging surveys reveal that the degradation is confined to cadmium yellow (CdS) paints. The discoloration of cadmium yellow paints in Impressionist, Post-Impressionist and early modernist work from the 1880s through the 1920s has been ascribed to the photo-oxidative degradation of CdS. Preliminary investigations of the degraded yellow paints in this work involved Cd LIII-edge X-ray Absorption Near Edge Spectroscopy (XANES) at the Stanford Synchrotron Radiation Light Source (SSRL Menlo Park, California) and Scanning Electron Microscopy-energy dispersive X-ray analysis (SEM-EDS) at the Winterthur Museum Scientific Research and Analysis Laboratory. To determine if the visual changes in the paints did in fact indicate photo-oxidative degradation and if different chemistries could be observed for the lightened versus darkened regions, synchrotron radiation-micro Fourier Transform InfraRed (SR-μFTIR) spectroscopy, X-ray Fluorescence (SR-μXRF) mapping and micro X-ray Absorption Near Edge Spectroscopy (μXANES) mapping at the Cd LIII-edge of the altered paint cross-sections were carried out at the European synchrotron radiation facility (ESRF, Grenoble, France) beamline ID-21. The goal is to elucidate the discoloration mechanisms observed in the paint using elemental and speciation mapping. The μXANES mapping and SR-FTIR imaging showed a substantial enrichment of CdCO3 in the off-white surface crust of the faded/discolored CdS paint. This suggests that the CdCO3 is present as an insoluble photodegradation product rather than solely a paint filler or starting reagent. Additionally, oxalates and sulfates were found to be concentrated at the alteration surface.

Combined use of Synchrotron Radiation Based Micro-X-ray Fluorescence, Micro-X-ray Diffraction, Micro-X-ray Absorption Near-Edge, and Micro-Fourier Transform Infrared Spectroscopies for Revealing an Alternative Degradation Pathway of the Pigment Cadmium Yellow in a Painting by Van Gogh

Over the past years a number of studies have described the instability of the pigment cadmium yellow (CdS). In a previous paper we have shown how cadmium sulfide on paintings by James Ensor oxidizes to CdSO(4)·H(2)O. The degradation process gives rise to the fading of the bright yellow color and the formation of disfiguring white crystals that are present on the paint surface in approximately 50 μm sized globular agglomerations. Here, we study cadmium yellow in the painting "Flowers in a blue vase" by Vincent van Gogh. This painting differs from the Ensor case in the fact that (a) a varnish was superimposed onto the degraded paint surface and (b) the CdS paint area is entirely covered with an opaque crust. The latter obscures the yellow color completely and thus presents a seemingly more advanced state of degradation. Analysis of a cross-sectioned and a crushed sample by combining scanning microscopic X-ray diffraction (μ-XRD), microscopic X-ray absorption near-edge spectroscopy (μ-XANES), microscopic X-ray fluorescence (μ-XRF) based chemical state mapping and scanning microscopic Fourier transform infrared (μ-FT-IR) spectrometry allowed unravelling the complex alteration pathway. Although no crystalline CdSO(4) compounds were identified on the Van Gogh paint samples, we conclude that the observed degradation was initially caused by oxidation of the original CdS pigment, similar as for the previous Ensor case. However, due to the presence of an overlying varnish containing lead-based driers and oxalate ions, secondary reactions took place. In particular, it appears that upon the photoinduced oxidation of its sulfidic counterion, the Cd(2+) ions reprecipitated at the paint/varnish interface after having formed a complex with oxalate ions that themselves are considered to be degradation products of the resin and/or oil in the varnish. The SO(4)(2-) anions, for their part, found a suitable reaction partner in Pb(2+) ions stemming from a dissolved lead-based siccative that was added to the varnish to promote its drying. The resulting opaque anglesite compound in the varnish, in combination with the underlying CdC(2)O(4) layer at the paint/varnish interface, account for the orange-gray crust that is disfiguring the painting on a macroscopic level. In this way, the results presented in this paper demonstrate how, through a judicious combined use of several microanalytical methods with speciation capabilities, many new insights can be obtained from two minute, but highly complex and heterogeneous paint samples.

Microanalytical characterization of decorations in handmade ancient floor tiles using inductively coupled plasma optical emission spectrometry (ICP-OES)

In this study a total of 114 glazed decorations of 42 ceramic floor tiles, manufactured in Sicily from the 16th to the 21th AD, were investigated. The micro sampling method, proposed by us, using a cotton swab soaked in hydrofluoric acid, includes advantages of high sensitivity, high selectivity, simplicity, speed, not expensive and can be considered non-destructive because the point of sampling remains invisible to the human eye. ICP-OES technique was used in this study. Twenty-four elements (Al, As, B, Be, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Ni, Pb, Sb, Se, Si, Sn, Ti, V and Zn) were determined in each colored enamel.Enameled decorations in Sicilian tiles were varied in tones and chromatic effects, obtained with a limited number compounds of cobalt, copper, iron, manganese, tin, and in the artifacts following the year 1920, also titanium. An important remark is that some of the colors, such as black, orange, purple and brown were prepared using the same metals, while white, light blue, blue and green were obtained with different elements. The adoption of different recipes for the same color suggests the presence of several laboratories of ceramists working in Sicily who had preferences for different methods for the production of their enameled artifacts.Concerning the opacifier, the high amounts of lead and antimony, only in a case, indicate the use of lead antimonate (Pb2Sb2O7). Black decorations were present in several of the analyzed samples and in most of them were identified mixtures of black iron and manganese oxides. The green decorations appear to have been prepared with copper oxide; lighter hue samples contained additional amounts of zinc and/or barium compounds. Considering all the samples, meanly, iron predominates in yellow decorations, only a sample contains large amounts of Cd, Zn and very little Sb, which suggests the use of the pigments ZnO (as white) and CdS as cadmium yellow. For all samples, except one, we can exclude the use of pigments containing chromium.

Joaquin Sorolla's pigment characterisation of the paintings ‘Vision of Spain’ by means of EDXRF portable system

In this work, portable energy dispersive X-ray fluorescence (EDXRF) spectrometry was employed to the characterisation of the palette used by the Spanish artist Joaquin Sorolla (1863–1923) in the paintings ‘Vision of Spain’, a set of 14 oils on canvas painted by Sorolla between 1911 and 1919 by order of Mr Archer Huntington to decorate the library of the Hispanic Society of America (HSA) in New York. The analyses, sponsored by BANCAJA and provided by the HSA, were carried out in situ, prior to the cleaning and restoration process, while the paintings hanging on the walls of the library of the HSA. The results revealed that the paintings were made over different priming layers containing, respectively, lead white, zinc and barium compounds, lead white mixed with zinc white or lead white mixed with zinc and barium compounds. The EDXRF analyses of coloured zones identified up to 29 inorganic pigments and, in some cases, the probable use of organic pigments. Sorolla used traditional pigments as earth pigments, lead white, vermillion, etc., and modern pigments as cadmium yellow, zinc white, cobalt-based blue, chromium-based green, manganese-based violet, etc. These results provide valuable information about the Sorolla's palette during the last stage of his life. Copyright © 2011 John Wiley & Sons, Ltd.

Application of photoacoustic infrared spectroscopy in the forensic analysis of artists’ inorganic pigments

Fourier-transform photoacoustic infrared (PAIR) spectroscopy has been used in the analysis of 12 inorganic pigments commonly in use by artists today, viz., cobalt blue, ultramarine blue, Prussian blue, azurite, malachite, chromium oxide, viridian, cadmium yellow, chrome yellow, iron oxide, yellow ochre and Mars orange. The authenticity of these 12 commercial pigments was first established by recording their Raman spectra. The subsequent PAIR spectra were highly reproducible and matched well in the mid-IR region with previously published data for these pigments. A number of additional overtone and combination bands were also detected that will prove useful in the identification of the pigments in the future. The PAIR technique is a promising and reliable method for the analysis of inorganic pigments, especially since it involves much simpler preparation than is required for conventional IR measurements.

Characterization of Brazilian artists’ palette from the XIX century using EDXRF portable system

In this work were characterized the palettes of some of the most representative Brazilian painters from the XIX century: Eliseu Visconti, Almeida Junior, Rodolfo Amoedo, Henrique Bernardelli, Rafael Frederico, Modesto Brocos, Augusto Rodrigues Duarte and Pedro Peres. EDXRF measurements were carried out with a portable system consisting of an X-ray tube Oxford TF3005 and a Si-PIN XR-100CR detector from Amptek. Some pigments identified were: zinc and lead white, ochre, umber, vermilion, Prussian blue, cobalt blue, cadmium yellow, black iron oxide, etc.

ATR-FT-IR spectroscopy in the region of 500–230 cm −1 for identification of inorganic red pigments

It is demonstrated that micro-ATR-FT-IR in the low wave number range (500–230 cm −1) can be well used for identification of pigments in paint samples thereby markedly extending the possibilities of pigment identification by ATR-IR spectroscopy into the realm of pigments having no absorptions in the mid-IR region. Reference spectra of pigments can be conveniently obtained by mixing them with linseed oil in approximately 1:1 mass ratio. Vermilion (or cinnabar), read lead, different red iron oxide pigments and cadmium red can be identified. In some cases the method can be used alone for pigment identification and in many cases it provides useful additional evidence for pigment identification using other instrumental techniques (electron microprobe analysis, XRF, optical microscopy).