XRF study on the gilding technique of the fresco ‘Crocifissione con Santi’ by Beato Angelico in the San Marco monastery in Florence

This study focused on the gildings of a famous Italian fresco, the Crocifissione con Santi by Beato Angelico, exploiting the XRF spectrometer developed at the LABEC laboratory. This can be considered the first scientific study on the gilding technique on frescoes of Beato Angelico. In order to characterise the original gilding technique and identify restored parts, more than 30 points were analysed in different areas of the wall painting, mostly in halos and decorations. In particular, the main goal was to verify whether Beato Angelico used the composite tin–gold foil, the most common gilding technique during the Italian Renaissance. This study allowed discriminating the original from the restored gildings, and to characterise the layers in both cases, by means of iron Kα/Kβ ratio. Copyright © 2015 John Wiley & Sons, Ltd.     

Analysis of mural paintings using in situ non‐invasive XRF,FTIR spectroscopy and optical microscopy

An analytical protocol consisting of X‐ray fluorescence spectroscopy, optical microscopy and Fourier transform infrared spectroscopy was used to study the origin and the nature of the materials (pigments, binders and coating preparation) of the Fundenii Doamnei church mural paint from Bucharest. The main interest of the present study consisted in the original votive paint from narthex, painted in 1757 in a secco technique. During analysis, an unexpected pigment in the votive paint could be detected by the combined analytical techniques: ultramarine blue. Along with this pigment, the presence of gypsum binder based on egg and flax seed oil could also be evidenced. These results demonstrated a secco execution technique of the votive paint and also the presence of a restoration treatment. Moreover, during the present study, the components of the preparation layer and the constitutive pigments from both 1699 and 1757 years mural paints have been analyzed. Hence, the following pigments could be identified: vermilion, azurite, cinnabar, lead white, ochre, natural umber and gold, by using the combination of the analytical techniques. The novelty of our results consists in detecting the composition of the materials used in this church painting (fresco and a secco) during these 254 years since its first restoration. The results of these investigations pointed to the suitability of the non‐destructive and semi‐destructive analytical techniques in the complex characterization of the paints realized in different techniques, at different periods. Copyright © 2013 John Wiley & Sons, Ltd.     

Portable XRF study of pigments applied in Juan Hispalense’s 15th century panel painting

Several medieval paintings and polychrome sculptures have been analysed in the frame of a collaboration between the Fine Arts Museum of Seville and the National Centre of Accelerators, dedicated to a non‐destructive study of artworks that belong to the wide museum’s collection. Among the oldest artworks in the collection is the panel painting Archangel St. Michael attributed to Juan Hispalense, one of the first painters in the 15th‐century Seville known by name. The panel was analysed by a portable X‐ray fluorescence (XRF) to get more information about the pigments applied and to identify possible later interventions. The results showed that the pigments were those commonly used in that period. Lead white was found in the preparation of the painting and in colour layers. For yellow colour, yellow ochre was used, while for the red one, the painter usually mixed red earth and vermillion. Blue pigment is azurite, while the copper‐based green one could not be determined more specifically by XRF. Brown colour is made with yellow ochre and organic black or, in some cases, umbra. Black pigment is probably bone or ivory black. Many decorative parts of the panel are gilded, which were confirmed by Au peaks. Later interventions were carried out on the base of Ti–Zn white mixed with earth pigments, while for green areas such as Archangel's wings also chrome green was applied. The research is part of a larger study which is still going on, whose aim is to gain more knowledge about the 15th‐ and 16th‐century Spanish painting and polychromy. Copyright © 2011 John Wiley & Sons, Ltd.     

Thickness determination of gold layer on pre‐Columbian objects and a gilding frame,combining pXRF and PLS regression

In conservation, restoration and characterization studies of art and archaeological objects, the improvement of analytical techniques is a tendency. X‐ray fluorescence (XRF) is a versatile technique, and it has been widely used in the last decades for characterization of a great variety of materials (metals, glass, paints, inks, ceramics, etc.) applied to cultural heritage studies. Besides the chemical composition, it is possible to infer the layer thickness through XRF, enabling a general knowledge of the manufacturing techniques implemented by the culture of origin, as well as the association with the technological level reached for the production of each kind of artefact. The aim of this study is to introduce an alternative way for gold thickness determination of coatings in cultural heritage objects, combining portable XRF data and partial least square regression. As a case of study, we present the use of this methodology in portable XRF measurements performed in situ on a gilding frame in Brazil and in two pre‐Columbian artefacts from Chavin culture in Peru. Gold layers with thicknesses determined by Rutherford backscattering spectrometry (RBS) were used as standards to perform a calibration model and to check the methodology before its application to unknown artefacts. Copyright © 2016 John Wiley & Sons, Ltd.     

Pigments characterization of polychrome vases production at Lipára: New insights by noninvasive spectroscopic methods

One of the most impressive Sicilian pottery production is attributed to the so‐called Lipari Painter and his followers, whose vessels—found in the archeological site of Lipari (Aeolian Island, Sicily)—are decorated with characteristic blue, red, and white figures. From the archeological point of view, these artworks keep open many questions concerning dating, production technique, and cultural background. In this context, new data on the manufacture procedures and on the raw materials used for the pigments may contribute to a deeper comprehension of this early Hellenistic vase tradition. The preciousness of the vessels, exhibited at the Archeological Museum of Lipari, imposed the use of in situ nondestructive methods to address new insights on the nature of the colored layers. Thus, analyses by Raman and X‐ray fluorescence spectroscopy have been performed with portable instruments on a selection of vessels certainly attributed to Lipari Painter and to some others of his followers. The results of this study testify the use of different pigments: kaolin and gypsum, probably supplied locally, for white layers; Egyptian blue for blue hues; red ochre for brown‐reddish hues; and cinnabar for pink and red‐purple nuances. The identification of both Egyptian blue and cinnabar opens an interesting discussion about dating and circulation of the raw materials.     

A critical analysis of the application of EDXRF spectrometry on complex stratigraphies

In this work, the potentialities and limits of the investigation by portable energy‐dispersive X‐ray fluorescence (XRF) of complex polychrome stratigraphies are discussed. Data are affected by the mutual influence effects of the chemical elements that characterize mineral pigments, by the sequence and the thickness of the paint layers in the stratigraphies and by the size of pigment grains. Sequences of pictorial layers, which produce the typical stratigraphy of cold‐painted terracotta and wooden sculptures, have been prepared and then analysed by means of two portable X‐ray spectrometers: Innov X Systems Alpha 4000 (Tantalum X‐ray tube, 40 kV and 7 µA) and Assing Lithos 3000 (Molybdenum X‐ray tube, 25 kV and 300 µA). For each layer of pigment, the XRF spectrum was acquired and the areas of K and L peaks of characterizing elements were calculated. Moreover, the thickness of the layers was determined using XRF data following an algorithm already shown and the values have been compared with those measured on polished cross sections observed by optical microscope in reflected light. Copyright © 2011 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.     

A pigment (CuS) identified by micro‐Raman spectroscopy on a Chinese funerary lacquer ware of West Han Dynasty

A blue pigment was identified by micro‐Raman spectroscopy, X‐ray fluorescence spectroscopy (XRF), scanning electron microscopy (SEM)/energy dispersive X‐ray (EDX) and X‐ray diffraction (XRD). The test sample, a funerary lacquer tray, belongs to West Han Dynasty (206 BC–AD 8) of China and was decorated with faint blue patterns. The result from Raman spectroscopy showed that the faint blue is covellite (CuS) due to the presence of a characteristic peak at 474.5 cm⁻¹, which further was confirmed by XRF, SEM–EDX and XRD. This research indicated that CuS had been used as a blue pigment to decorate lacquer wares from the West Han Dynasty in China. Copyright © 2009 John Wiley & Sons, Ltd.     

Gemstones and noble metals adorning the sceptre of the Faculty of Science of Charles University in Prague: integrated analysis by Raman and XRF handheld instruments

A commonly marketed handheld Raman spectrometer showed excellent possibilities in being used as a key instrument for unambiguous identification of gemstones mounted in the sceptre of the Faculty of Science of Charles University in Prague from the mid‐20s of the 20th century. Numerous SiO₂ forms including chalcedonies intermixed with moganites (e.g. moss agates and carnelians), amethysts, citrines as well as garnets (pyrope–almandines) were identified. The estimation of the garnet type was based on obtained Raman parameters. The individual minerals constituting the lapis lazulis could not be discerned because of very high fluorescence they exhibited in the fingerprint region of the Raman spectrum, nevertheless the positions of the observed peaks in the 1000–2000 cm^–1 area were in very good agreement with the values of commercially available lapis lazuli pigment. The noble metals of the sceptre were studied by means of X‐ray fluorescence analysis, which confirmed the presence of silver alloys and gilding. The comparison of silver alloys' semiquantitative analysis with the expected fineness, denoted by the hallmarks, indicated silvering. This has been later confirmed by the newly discovered restoration documentation. Portable handheld Raman and X‐ray fluorescence instruments represent an ideal tool for studying historical artefacts, where an in situ investigation in museums or similar sites is obligatory. Copyright © 2012 John Wiley & Sons, Ltd.     

唐代苏同家族墓天王俑彩绘的光谱分析

天王俑是中原地区的达官贵人墓葬的镇墓俑,是唐墓葬冥器中重要的一种神煞俑。为探究天王俑彩绘颜料的组成元素以及彩绘工艺,使用X射线荧光光谱分析了陕西省咸阳市渭城区苏同家族墓KTJ-2019-019M2、 KTJ-2019-019M3坑出土的天王俑彩绘区域的元素组成。分析结果表明陶俑表面金色贴片主要为金箔(Au);红色颜料的组成元素则是Hg、 S以及少量的Pb、 P;蓝色颜料和绿色颜料的组成元素均为Cu,白色颜料的组成元素为P、 S、 Pb。使用拉曼光谱对彩绘颜料层的鉴定物相,使用拉曼光谱分析技术对彩绘层分析结果确定了红色颜料的主要组成物相为朱砂(HgS)和铅丹(Pb₃O₄)的混合颜料;蓝色颜料的主要组成物相为石青;绿色颜料的主要组成物相为石绿;白色颜料的组成物相可能为铅白。进一步使用XRF面扫描技术分析了天王俑的彩绘工艺,解析金、红、蓝、绿色区域的组成元素位置,发现陶块样品中的M₂-1金色陶块、 M₃-1白色陶块、 M₃-2红色陶块、 M₃-3蓝色陶块、 M<...     

Spectroscopic investigation of modern pigments on purportedly medieval miniatures by the ‘Spanish Forger’

Five miniatures by the so‐called ‘Spanish Forger’ were acquired by the Victoria and Albert Museum in 2008. Believed to be authentic medieval miniatures until the mid‐twentieth century, they are now considered to have been painted around the end of the nineteenth and the beginning of the twentieth century. To investigate this attribution and to gather detailed knowledge about the materials used by the artist, a comprehensive pigment analysis by Raman microscopy and X‐ray fluorescence was carried out. Although traditional materials such as vermilion, carbon black, red lead, lead white and indigo were identified, many others (chrome yellow, Scheele's green, emerald green and ultramarine blue) are modern and synthetic pigments, a result which provides a firm scientific basis for stating that the miniatures are forgeries. Copyright © 2009 John Wiley & Sons, Ltd.     

Non‐destructive characterization of 17th century painted silk banner by the combined use of Raman and XRF portable systems

X‐ray fluorescence spectroscopy (XRF) and Raman spectroscopy analysis were performed to examine a 17th century painted silk banner in order to characterize the pigments and materials used. This complementary approach yields information on the elemental (XRF) and on the molecular composition (Raman) of the used compounds. The paint layer, ground layer under gilding, and gilding layer were investigated. For the studied object, vermilion (HgS), lead white (2PbCO₃ · Pb(OH)₂), red lead (Pb₃O₄), and aurichalcite ((Cu,Zn)₅(CO₃)₂(OH)₆) were found. The presence of silver and gold foils was confirmed. The techniques used in the analysis were portable, non‐destructive, and non‐invasive, which is very desirable when analyzing cultural heritage objects. The obtained results were used by the conservators to develop a showcase prototype for safe exhibition. Copyright © 2015 John Wiley & Sons, Ltd.     

Multispectroscopic Characterization of Oil on Copper Painting

A small plate of oil on copper painting from the Italian Renaissance period was characterized by means of noninvasive spectroscopic methods. The study was conducted by the use of energy-dispersive X-ray fluorescence, X-ray diffraction, and Raman and diffuse reflectance infrared Fourier transform spectroscopies to determine the technology production process in such kinds of artworks. Results allowed us to characterize the copper alloy of the support media; the preparation layer, which is composed by white lead; and the pictorial layer of variable composition (green copper sulphate compounds, red lead, carbon black, brown earth pigments, gold, vermilion, and white lead). The complementarity of the techniques used in this study has proven to be highly effective.     

Thickness and composition of gold and silver alloys determined by combining EDXRF‐analysis and transmission measurements

Energy‐dispersive X‐ray fluorescence (EDXRF)‐analysis is a technique which in the case of metals analyzes thin surface layers. For example, when gold and silver alloys are analyzed, it typically interests a depth of microns up to a maximum of tens of microns. Therefore, it can give wrong results or be affected by a large indetermination when the sample composition is altered because of surface processes, as often happens when silver alloys are oxidated, and sometimes in the case of gold alloys rich on copper or silver. A complementary technique was therefore developed, of bulk analysis, which uses the same equipment employed for EDXRF‐analysis; the X‐ray beam from the X‐ray tube is monochromatized by means of a tin secondary target, which K lines bracket the silver‐K discontinuity. The sample to be analyzed is positioned between the secondary target and the detector. This technique is able to determine (by measuring the attenuation of tin‐K rays) thickness and/or composition of gold and silver alloys having a thickness of less than about 120 µm for gold and about 0.7 mm for silver. The method was tested with Au–Ag–Cu alloys of known composition and thickness and then applied to gold and silver artifacts from the tomb of the Lady of Cao, which belongs to the Moche pre‐hispanic culture from the North of Peru, and dates about 300 A.D. Copyright © 2014 John Wiley & Sons, Ltd.     

Raman Characterization of Pigments in Painted Beams and a Wall Painting Discovered in the San Francisco Church in Santiago,Chile

A material characterization of two artworks discovered in the San Francisco Church, Santiago, Chile, was performed using micro-Raman spectroscopy. Structural painted beams and a wall painting that belong to the same time period, between the end of the 17th and 19th centuries, were analyzed. The cross-section samples of both artworks were characterized and animal protein was identified in the ground layer in both cases. The supporting material of the beams was identified as cypress wood, and a rag paper layer was used as a base for the paint layer, which is composed mainly of a white ground layer on which the color was subsequently added; the yellow pigments are orpiment and chrome yellow; the green color probably arises from a mixture of orpiment, red lead, ultramarine blue, and calcite. A complete analysis of the materials using complementary techniques such as microchemistry and optical microscopy indicates that the mural was painted using a mixed technique and that organic and inorganic pigments were used. The identification of the synthetic pigment ultramarine blue in some blue areas of the wall revealed a modification of the wall painting in the 19th century; dark blue areas resulted from a mixture of indigo, palygorskite, and lazurite.     

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.     

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.