Synthetic organic pigments in contemporary Balinese painting: a Raman microscopy study

The colour palette from two 20th century and one 21st century Indonesian paintings from the island of Bali was determined by Raman microscopy. There is very little information concerning the artistic techniques from this region of the world and the influences in materials introduced by western artists. The most interesting finding of our study was the increasing substitution of natural pigments by modern synthetic organic pigments. The findings were also compared with samples of representative pigments commonly used by Bali artists, donated by a renowned Balinese painter. Raman microscopy, combined with Fourier transform infrared spectroscopy, high‐performance liquid chromatography and μ‐EDXRF, was able to separate the different components on several colours, and to identify both synthetic organic pigments and inorganic components. Three azo pigments from the diarylide subclass, PY 83, PY 55 and PO 16, were identified on the yellow, brown, red and orange colours. A copper phthalocyanine blue PB 15:x and a basic dye BB 26 were responsible for the blue colours, the former admixed with ultramarine blue. Goethite was sometimes introduced to create the green colour. Two other basic dyes, BY2 and PG 4, were the main chromophores of the yellow and green samples of local pigments. The inorganic pigments comprised bone white, bone black, carbon‐based black pigment, haematite, goethite, vermilion, ultramarine blue and anatase. Finally, the ground layer of all the paintings was identified as rice starch, with a double function of a white pigment. Copyright © 2012 John Wiley & Sons, Ltd.     

Testing of Raman spectroscopy as a non‐invasive tool for the investigation of glass‐protected miniature portraits

Six French miniature portraits on ivory and paper dating back to the 18th to 19th centuries have been studied by Raman spectroscopy. The miniatures have been investigated through their protective glass cover using different operating conditions: various laser wavelengths (1064, 785 and 532 nm), spectrometers (fixed and mobile) and objectives (10× to 200×). The results obtained for black (carbon), grey (carbon + chalk), red (lead oxide, vermillion), blue (Prussian or phthalocyanine blue), green (emerald or Paris green) and white (lead white) pigments are presented. The consistency of the period of use of the pigments with the proposed dating for each artwork is evaluated. Attention is paid to the analysis of the ivory substrates (assigned to Asian elephant ivory) and to the protective glass. Copyright © 2011 John Wiley & Sons, Ltd.     

Raman spectroscopy of synthetic organic pigments used in 20th century works of art

Raman microscopy allows a non‐destructive characterisation of inorganic and organic painting materials such as pigments and organic dyestuffs. The objectives of this study are the more recent organic pigments typically present in paintings and other art works from the 20th century. More than 20 organic synthetic pigments from different chemical classes could be identified by Raman spectroscopy using different excitation wavelengths (457.9, 476.5, 487.9, 514.5, 632.8, and 1064 nm). To evaluate the performance for real paint samples, varying paint mixtures of the Hansa Yellow pigment PY 3 and the binding medium Mowilith, a polyvinyl acetate (PVAC) compound, were characterised; PY 3 was determined at a 1 wt% level in the binder. In addition, commercial tube paints containing the quinacridone violet PV 19 were studied. The pigment was clearly identified in all of these more complex oil and acrylic paints. Finally, alizarin (PR 83) and a green copper phthalocyanine pigment (PG 7) could unambiguously be identified by Raman microscopy in the painting ‘Woman with mandolin in yellow and red’ of Max Beckmann dating 1950. The discovery of a red naphthol AS pigment by Raman spectroscopy in a sample from the ‘Three field workers’ by Georg Baselitz (1964/1965) demonstrated that in some cases complementary chromatographic methods are needed for a comprehensive identification of the organic pigments. Copyright © 2008 John Wiley & Sons, Ltd.     

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.     

西藏扎什伦布寺壁画的科学研究

壁画是寺院建筑的重要装饰元素,也是藏传佛教艺术的重要组成部分。扎什伦布寺始建于明正统12年（公元1447年）,作为后藏最大的寺院,寺内保存了大量精美壁画,这些壁画对研究藏传佛教及佛教艺术具有重要意义。扎什伦布寺自建寺起一直为传播佛教文化服务,经历了频繁的大规模修建。为了解扎什伦布寺壁画的制作材料与工艺,为今后壁画的保护及修复提供重要的参考及科学支撑,选取寺内强巴佛殿四层北壁、吉康扎仓南殿西侧的典型壁画,共采集8个样品。采用超景深三维视频显微镜观察壁画的制作结构,显微激光拉曼光谱仪对有机与无机颜料的成分信息进行表征,偏光显微镜根据晶体的光学信息鉴别拉曼光谱相似的颜料颗粒,X射线衍射仪用于测定地仗成分,扫描电镜/能谱仪则对微观数据进行确认和补充。通过分析研究,壁画由地仗层、准备层、颜料层构成。颜料包括矿物及人工合成颜料,其中红色颜料为朱砂与颜料红14,绿色颜料为块铜矾、酞菁绿,黑色颜料为碳黑,黄色颜料为雌黄,蓝色颜料为合成群青。颜料红14与酞菁绿为有机合成颜料,合成群青则为无机合成颜料。块铜矾作为矿物颜料,在欧洲曾用于架上画、壁画、手稿等艺术作品中,但在国内还未曾发现其使用历史,这一发现扩展了对绿色颜料的认识。壁画的地仗层依据藏式壁画制作传统使用了阿嘎土,准备层则由黄土制备。研究结果表明,壁画制作时以阿嘎土打底,刷一层黄土找平壁面,以胶调和颜料绘制于黄土层之上。壁画除了使用一些常见的传统藏式壁画材料,还发现了一些近代人工合成材料,说明扎什伦布寺强巴佛殿四层北壁及吉康扎仓南殿西侧壁画曾经历过重绘或补绘。该研究结果不仅弥补了扎什伦布寺壁画的研究空缺,也为扎什伦布寺修缮历史的补充及完善提供了重要证据。     

Identification of pigments from the Shrine of Kaiping Diaolou by micro‐Raman spectroscopy

Shrines (or altars) are constructed in China for worshiping ancestors, Bodhisattva, and God of Wealth. In this work, pigments from the shrine of Kaiping Diaolou tower were analyzed by micro‐Raman spectroscopy, in conjunction with other analytical methods including scanning electron microscopy (SEM) with energy dispersive X‐ray spectroscopy (EDX) and X‐ray fluorescence (XRF). Paintings of the shrine were composed of 2–3 pigment layers and the total thickness was determined as about 200–300 µm by optical microscopy and SEM, indicating the fine painting skills applied in the construction of the shrine. The green pigments on the surface layer of the green fragment were identified as a mixture of lead phthalocyanine (PbPc) and cornwallite (Cu₅(AsO₄)₂(OH)₄) by XRF and micro‐Raman spectroscopy with two different excitation wavelengths (488 and 785 nm). Underneath the green layer, red and yellow ochre were found. The pigments on the surface layer of red and blue fragments were identified as hematite (Fe₂O₃) and lazurite or synthetic ultramarine [(Na₈(Al₆Si₆O₂₄)S₃)], respectively. Finally, the pigments under the two surface layers were identified by EDX and micro‐Raman spectroscopy as chromium oxide (Cr₂O₃), gypsum (CaSO₄·2H₂O) and calcite (CaCO₃). Copyright © 2011 John Wiley & Sons, Ltd.     

中国古代艺术品常用矿物颜料的拉曼光谱

拉曼光谱技术在艺术品文物和考古学领域的应用正变得日益重要, 其中对艺术品文物中所使用的颜料的分析是这方面应用的一个重要研究课题, 本文讨论了有关的实验技术, 测量了一些在中国古代艺术品中经常使用的红色、黄色和白色颜料的拉曼光谱, 介绍了相关的背景知识, 并对这些光谱进行了解析, 这些基础数据对于进一步开展对古代壁画、彩塑、雕刻、陶瓷等的拉曼光谱分析有着重要的基础参考价值。     

Testing of Raman spectroscopy as a non‐invasive tool for the investigation of glass‐protected pastels

Five French pastels and a sanguine drawing dating from the 17th to the 20th century were studied by Raman spectroscopy. Different operative conditions were used: the pastels were investigated through their protective glass, and the results obtained were compared with those obtained after removing the glass and after sampling a micrometric particle of pigment. Different parameters (wavelengths, powers of excitation and objectives) were tested in order to assess the optimal procedure of analysis for this fragile work of art. The results obtained for black (carbons), yellow (chrome/cobalt yellow), red (lead oxide, vermillion, orpiment), brown (red lead and chrome yellow), blue (Prussian blue, lapis lazuli/ultramarine), green (mixture of above blue and yellow pigments) and white (calcite, lead white, anatase) pigments are presented and the consistency of the pigments' period of use with the dating proposed for each pastel is evaluated. In one of the pastels, the blackening of the carnation colour made of an unstable mixture of lead white, red lead and vermilion was studied. Copyright © 2010 John Wiley & Sons, Ltd.     

Three fabricated pigments (Han purple,indigo and emerald green) in ancient Chinese artifacts studied by Raman microscopy,energy‐dispersive X‐ray spectrometry and polarized light microscopy

In this study, we analyzed three fabricated pigments from ancient artifacts in China. The purple pigment was obtained from a painted pottery figurine unearthed from the Chu Tombs group of the Western Han dynasty in Xuzhou, Jiangsu Province. The dark blue dye was from silk textiles in the Palace Museum. The green pigment was from decorative paintings on ancient architectures in the Palace Museum. These pigments were analyzed with Raman microscopy (RM), energy‐dispersive X‐ray (EDX) analytic spectroscopy and polarized light microscopy (PLM). By comparing their Raman spectra with standard samples, the primary ingredients of the purple pigment and the dark blue dye were found to be Han purple and indigo, respectively. However, the green pigment could not be identified by RM because of strong fluorescence. It was then confirmed to be emerald green by using EDX analytic microscopy and PLM. We also describe the traditional manufacturing methods of these pigments and their applications on artifacts in Chinese history. Copyright © 2007 John Wiley & Sons, Ltd.     

The use of Raman microscopy and laser desorption ionization mass spectrometry in the examination of synthetic organic pigments in modern works of art

Synthetic organic pigments are widely used in modern and contemporary works of art. They have been examined by a variety of techniques including spectroscopic methods such as Fourier transform infrared spectroscopy, Raman, and X‐ray powder diffraction as well as chromatographic or mass spectrometric techniques such as pyrolysis‐gas chromatography/mass spectrometry and laser desorption ionization mass spectrometry (LDI–MS). Often, a combination of techniques has been used to examine these pigments. This paper describes use of Raman spectroscopy to create a database of colorants including two pigments not previously reported, PO1 and PO2. Then, using Raman spectroscopy in combination with LDI–MS, samples from modern works of art by artists including Mark Rothko, Barnett Newman, and José de Rivera were examined in order to identify the pigments present. One finding was that Rothko used a variety of red pigments over the course of his career including PR11 which has not been previously reported in artwork, and PO2 found with its positional isomer PR1. Knowledge of the colorants serves to inform conservators about display and treatment decisions. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.     

The first Raman spectroscopic study of San rock art in the Ukhahlamba Drakensberg Park,South Africa

San rock art sites are found throughout southern Africa; unfortunately this unique heritage is rapidly being lost through natural weathering processes, which have been the focus of various studies conducted in the uKhahlamba Drakensberg Park since 1992. It has recently been shown that the ability of Raman spectroscopy to identify salts on rock faces on a micro, as well as nano scale, can make a contribution to these projects. In order to test the feasibility of undertaking on‐site analyses, a small rock fragment with red and white pigments still attached, which had weathered off the rock face, was analysed with Raman spectroscopy under laboratory conditions, using a Dilor XY Raman instrument and a DeltaNu Inspector Raman portable instrument. A small sample of black pigment (<1 mm²), collected from a badly deteriorated painting and a few relevant samples collected on site, were analysed as well. It was possible to identify most of the inorganic pigments and minerals detected with previous XRD and EDX measurements including whewellite and weddellite coatings, which could be a tool for carbon dating purposes. Two carotenoid pigments were detected for the first time in San rock art pigments. Animal fat was also observed for the first time on both red and white pigments, on the rock face adjacent to the paintings and in highest concentrations on the back of the rock fragment. The spectra quality makes successful on‐site measurements a good prospect. Copyright © 2008 John Wiley & Sons, Ltd.     

A multi-analytical approach for the study of the pigments used in the wall paintings from a building complex on the Caelian Hill (Rome)

In the present study, shards from Roman wall paintings (from the end of the first century to the fourth century A.D.) decorating the domus below the Basilica of SS. John and Paul on the Caelian Hill (Rome), were analyzed in order to identify the pigments used. The analytical techniques employed for the characterization of the pigments were the scanning electron microscope coupled with an energy dispersive spectrometer (SEM-EDS) and infrared spectroscopy (ATR and micro ATR). While SEM-EDS allowed to perform a qualitative analysis of the material, by FT-IR chemical species have been identified. The pigments identified were those mentioned in the literature for the Imperial Roman fresco painting: different types of ochre (yellow and red), mixtures containing lead, green earths and precious pigments such as cinnabar and Egyptian blue. They were often used as mixtures and the use of the most valuable pigments (cinnabar and Egyptian blue) were found in the most ancient rooms.     

Characterization of pigments used in painting by means of laser-induced plasma and attenuated total reflectance FTIR spectroscopy

The study of pigments which are found in the works of art is one of the most important tasks in the examination of historic, artistic and archaeological materials since it can provide information about their source, the pictorial technique used or the presence of restoration works.In some studies, the historical, artistic and technical characterization of the artefact is not the final goal but its restoration. In those cases, the knowledge about the chemical composition inferred from the analysis of the artwork is crucial for conservators and restorers in order to ensure that the same pigments that were used in the original work are employed for the restoration.In this work, the analytical characterization of a range of different pigments commonly used in art has been carried out using laser-induced plasma (LIBS) and attenuated total reflectance (ATR)-FTIR spectroscopy. The main purpose of this study is to provide a preliminary database of LIBS and ATR-FTIR spectra in order to supply both elemental and molecular information, respectively.     

Identification of Pigments in Colored Layers of a Painting by Raman Spectroscopy

Using the method of Raman spectroscopy the pigment composition is investigated of, and the brushwork technique used in, the original layer of a 19th century painting is established. It is an overdoor worked, presumably, by Antoine Jean-Etienne Faivre. It is established that the artist used the following pigments: cinnabar and dyes on the basis of goethite and hematite (for red, yellow–orange, and brown shades), ultramarine and Prussian blue (for blue shades), and Emerald green and a mixture of blue and yellow shades (to obtain a green color). It is determined that white lead was used a primer.     

中国古代艺术品常用矿物颜料的拉曼光谱(二)

在本刊前一篇文章中,我们讨论了拉曼光谱在艺术品分析和考古学应用方面的实验技术并报道了一些中国古代艺术品中经常使用的红色、黄色和白色矿物颜料的拉曼光谱。本文延续前文工作,测量了一些中国古代艺术品中常用的蓝色、绿色和黑色矿物颜料的拉曼光谱,介绍了相关的背景知识,并对这些光谱进行了解析,我们相信,一套比较全面的颜料拉曼光谱数据,对于拉曼光谱技术在考古学和艺术品分析方面的应用将会起到重要的参考价值。     

故宫奉先殿清初彩画颜料成分分析

故宫奉先殿是明清两代皇帝祭祀祖先的家庙,地位仅次于太庙。奉先殿始建于明成祖时期,现存建筑主要建于康熙时期,其上保留了为数不多的清初彩画,是研究清初彩画的珍贵实物。利用显微观察、扫描电子显微镜能谱和激光拉曼光谱分析,对取自奉先殿的彩画颜料进行分析鉴定。结果表明,奉先殿彩画中部分红色和蓝色颜料层存在分层现象,表层颜色鲜艳明亮,中层和下层颜色偏浅,每层所用颜料配方不同。红色颜料有朱砂、铅丹和铁红,绿色颜料均为氯铜矿,蓝色颜料均为石青,用铅白打底。浅色颜料由主显色矿物颜料加入以铅白为主的白色颜料混合调制而成。其中浅红色由铅丹与铅白调和而成,浅绿色由氯铜矿与铅白调和而成。浅蓝色颜料中未发现铅白,但含有大量Al元素和Si元素,推测含有高岭土。浅蓝色颜料有可能是由石青与高岭土调制而成。奉先殿彩画中未发现清晚彩画常用的合成群青、巴黎绿等颜料,反映出奉先殿彩画的绘制年代很有可能就是档案记载的康熙年间,之后未有大修。高岭土作为白色颜料调配浅色颜料在彩画制作中比较少见,奉先殿彩画中高岭土的发现丰富了清代早期彩画颜料制作的资料,具有一定的学术意义。     

Revealing the invisible: using surface‐enhanced Raman spectroscopy to identify minute remnants of color in Winslow Homer's colorless skies

The fading of pigments in items of importance to cultural heritage, such as paintings, works of art on paper, and textiles, is a ubiquitous problem. Tools currently available that can detect and identify organic colorants in severely degraded works of art are rare, given the heavy deterioration and restricted availability of the sample. Recently, however, surface‐enhanced Raman scattering (SERS) spectroscopy has shown great promise in detecting and identifying mass‐limited samples. The art conservation field has seized upon the opportunity opened up by this powerful analytical technique to enable the identification of microscopic amounts of organic molecules used as artists' colorants in complex matrices, such as biomaterials (i.e. dyed natural textiles, linseed oil biofilms present in oil paintings, etc.), a possibility that was previously precluded due to interfering fluorescence and small sample size. Here, we report SERS spectra recorded directly on single particles of red lake pigments from an important historical watercolor by the American master Winslow Homer (1836–1910) that suffered some degree of fading. The accurate colorant identification provided by SERS, enhanced by comparison with reference samples of historical watercolors, has thus enabled important discoveries regarding the materials and intended meanings behind artworks from one of the most influential American watercolor painters. Copyright © 2011 John Wiley & Sons, Ltd.     

New insights into the colour origin of archaeological Egyptian blue and green by XAFS at the Cu K‐edge

New results on the local chemical environment of Cu²⁺ in archaeological Egyptian blue and green and also modern Egyptian green were obtained by x‐ray absorption fine structure (XAFS) analysis. The information is essential for the understanding of the colouring mechanisms in both pigments. In a previous study, a clear physico‐chemical characterisation of Egyptian blue and green was achieved using a complementary analytical approach with ancient and modern synthesized pigments. Electron microscopy (SEM–EDX and TEM), x‐ray diffraction and micro‐Raman and UV–visible spectroscopy were used to gain information about the conditions of the ancient Egyptian fabrication processes and permitted the clear distinction of both pigments. However, the exact colouring mechanisms could not be elucidated by these methods. Different Cu‐bearing amorphous and crystalline phases were found in both pigments. These phases should be at the origin of the blue and turquoise colours. Using XAFS data at the Cu K‐edge, new insights into the origin of the colouring mechanisms of both pigments could be obtained from the precision of the Cu speciation. In Egyptian blue, Cu²⁺ is mainly allocated in a square‐planar site in a crystalline cuprorivaite phase, whereas in Egyptian green, Cu²⁺ is basically situated in a distorted octahedral site in an amorphous phase. Copyright © 2006 John Wiley & Sons, Ltd.     

Scientific investigations of the Imperial Gates from the Petrindu wooden church,Salaj County,Romania

In order to preserve and restore the Imperial Gates from the Petrindu wooden church, Salaj County, Romania, (map location—latitude, longitude: 46.97, 23.19), the scientific investigation of the wooden support and painting materials (ground and pigments) was performed, employing Fourier‐transform infrared spectroscopy (FTIR), X‐ray fluorescence spectroscopy, and 3D scanning. FTIR spectroscopy offered information about the wooden degradation stage, whereas X‐ray fluorescence and FTIR spectroscopic methods were employed for structural painting materials characterization. The structural data can be correlated with the artistic, theological, and historical analysis of this religious patrimony object. After obtaining information about the wooden support and painting materials, the Imperial Gates were 3D digitized using state of the art laser scanning technology. The digital 3D model obtained was restored in a virtual environment and converted into an interactive 3D model that can be used for Romanian cultural heritage digital dissemination.