Comparison between micro-Raman and micro-FTIR spectroscopy techniques for the characterization of pigments from Southern Spain Cultural Heritage

A Multi-Analytical Approach to Identify Colorants in the Qajar Painted Wooden Decorative False Ceilings, From Northwest Iran

The purpose of this study was to analyze the pigments used in the wooden paintings of Zarir Mosque, dating back to the Safavid era in Maragheh, Iran. These paintings, known as "Pardu," were commonly used for decorative false ceilings in various regions of Iran, particularly the northwest, during the Safavid and Qajar periods. Raman spectroscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy, multiband imaging, and optical microscopy were employed to examine the pigments. Fourier-transform infrared spectroscopy was also used to investigate the binder. The results indicated the use of orpiment, red lead, artificial ultramarine, carbon black, and gypsum for yellow, red, blue, black, and white pigments, respectively. Light blue colour was achieved by mixing gypsum and indigo, and gypsum was used as the primer layer in the painting. The presence of a protein-based binder, likely egg tempera, was confirmed through FTIR spectroscopy. The presence of artificial ultramarine suggests that these paintings were created after 1828, when it was first synthesized, placing them in the Qajar period. The presence of an inscription from 1280 AH suggests that these panels may have been produced during the extensive renovations of the mosque in 1280 AH (1864 AD), during the Qajar era.

A Study on the Materials Used in the Ancient Architectural Paintings from the Qing Dynasty Tibetan Buddhist Monastery of Puren, China

Situated in the village of Lama Temple on the eastern bank of the Wulie River in Chengde, Puren Temple stands as one of the few remaining royal temples of great importance from the Kangxi era (1662-1722 AD). This ancient edifice has greatly contributed to the advancement of our comprehension regarding the art of royal temple painting. The present study undertakes a comprehensive analysis and identification of nine samples obtained from the beams and ceiling paintings within the main hall of Puren Temple. Furthermore, a systematic examination of their mineral pigments and adhesives is conducted. The findings from polarized light microscopy (PLM), energy-type X-ray fluorescence spectrometer (ED-XRF), micro-Raman spectroscopy (m-RS), and X-ray diffractometer (XRD) analyses reveal that the pigments present in the main hall beams of Puren Temple are cinnabar, lead white, lapis lazuli, and lime green, while the pigments in the ceiling paintings consist of cinnabar, staghorn, lead white, lapis lazuli, and lime green. The use of animal glue as a binder for these pigments on both the main hall beams and ceiling paintings is confirmed via pyrolysis-gas chromatography-mass spectrometry (Py-Gc/Ms) results. These findings hold significant implications for the future restoration of Puren Temple, as they provide valuable guidance for the selection of appropriate restoration materials.

Cyclododecane shaping, sublimation rate and residue analysis for the extraction of painting micro-samples from resin cross-sections

Cross-section preparation of painting micro-samples is part of their routine analysis. This type of preparation can be used for several analytical techniques, such as scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and optical microscopy. These techniques offer high-resolution imaging and/or elemental information, providing access to technical and material data important for the interpretation, preservation, and restoration of painted artworks. However, it also means that the material from the sample embedded in the resin becomes unreachable for further analysis, except for the polished surface of the cross-section. Degradation of the embedding medium can also occur over time, which can lead to misinterpretation, loss of information, or even complete destruction of the embedded sample. In the field of cultural heritage, cyclododecane (CDD) is commonly used for the consolidation and protection of objects, and is used in the preparation of cross-sections to prevent contamination of the sample by the embedding medium. This study enhanced the existing preparation process by shaping the CDD layer to enable extraction of the micro-sample from the resin if needed, without compromising the integrity of the sample. Moreover, the purity, the sublimation rate in a normal environment and a vacuum, and the impact of CDD on three different types of samples (historical painting on a canvas, wall painting fragment, model sample) were examined.

A Multi-Analytical Approach to Investigate the Polychrome Clay Sculpture in Qinglian Temple of Jincheng, China

This article presents an integrated analytical method to investigate the polychrome clay sculptures of the Qinglian Temple in Jincheng City, Shanxi Province, China. Digital microscopy, SEM-EDS, XRD, Herzberg stain, Micro-Raman spectroscopy and FT-IR were selected to identify the raw materials and techniques used to produce the ground clay layer, the white powder layer and the mineral pigment of the polychrome clay sculptures. The investigation shows that the clay used to make the coarse and fine clay layer is consistent. However, different kinds of fibres were found mixed in the coarse and fine clay layers: wheat straw was the main fibre used in coarse clay layer, while the bast fibres, including ramie, kenaf and sisal hemp, were used as the fibre supports in the fine clay layers due to their useful properties. The white powder layer was made of a mixture of kaolinite and gypsum. For the mineral pigments, it principally contained red (hematite, minium or a mixture of minium and cinnabar), green (atacamite and atacamite), blue (azurite), yellow (yellow ochre), black (amorphous carbon) and white (the mixture of kaolinite and gypsum). Additionally, a gilding technique and multiple paint layers also typified many pigment areas. This work has furthered understanding of the materials and techniques used in making the sculptures of the Qinglian Temple and has clear implications for the restoration and conservation treatments on these kinds of ancient painted clay sculptures.

Palmyrene Polychromy: Investigations of Funerary Portraits from Palmyra in the Collections of the Ny Carlsberg Glyptotek, Copenhagen

The current study is the first comprehensive investigation of the polychromy of Palmyrene funerary portraits. It presents the technical examinations of six portraits (ca. 150–250 CE) from the collection of the Ny Carlsberg Glyptotek, illustrating the marvellous splendour of the cultural heritage of ancient Palmyra. The six portraits were examined with various analytical methods, including microscopy, ultraviolet-induced visible fluorescence imaging and visible light-induced infrared luminescence imaging, X-ray fluorescence spectroscopy, scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. Finally, two samples were collected for liquid chromatography–tandem mass spectrometry to obtain the amino acid sequence information. Various pigments were detected in the polychromy including lapis lazuli, pyromorphite, mimetite, yellow ochre, red ochre, a red lake, lead carbonate, zinc oxide, bone black, and charcoal black. The proteinaceous binding medium was identified as collagen-based and possibly also keratin-based animal glue. The examinations of the Palmyrene portraits in the Ny Carlsberg Glyptotek have proven that these artefacts, despite their current uniform, white appearance, originally presented themselves in a wealth of colours. This is illustrated by the digital reconstructions carried out of two of the examined portraits, which show how the original painting of these portraits would have given them an entirely different expression from what we see today.

A Multi-Analytical Investigation of Roman Frescoes from Rapoltu Mare (Romania)

(1) Background: Due to the precarious situation of many monuments or archeological sites, analytical investigations are necessary to obtain information about the used materials, as well as to identify the most appropriate solutions for their conservation/restoration. This paper addresses the characterization of mural painting fragments collected during the excavation in 2018 in Rapoltu Mare (La vie), Deva. (2) Methods: Specific analytical techniques were used, as follows: X-ray diffractometry (XRD), wavelength dispersive X-ray fluorescence (WDXRF), optical microscopy (OM), zoom microscopy and scanning electron microscopy (SEM), spectroscopic techniques (UV–Vis, FTIR, Raman), porosity and thermal analysis, all of which provide information about the structure, chemical composition, morphology and topography of pigments and their deterioration as well. (3) Results: Up to seven different pigments were identified: Egyptian blue, carbon, calcite, gypsum, hematite, goethite and green earth. Egyptian Blue is identified in all the other color areas, except the white area: in the green zone (as degradation product with beeswax) and in the red zone (in mixture with ochre) too. In addition, carbon and beeswax were highlighted as toner and binder for pigments, respectively. In the presence of the organic beeswax binding environment, the Egyptian blue pigment particles darkened or turned yellow significantly, changing the blue to a greenish color. It is also possible to identify wollastonite (CaSiO3) in the blue pigment, which indicates that the temperature used in the manufacturing of Egyptian blue was higher than 950 °C from thermal analysis. The presence of apatite, hematite and gypsum deposits in the Hunedoara region certifies that these pigments could have been of local origin, as demonstrated by the presence of analytically identified elements (Fe, P, S, Ca). (4) Conclusions: The analytical techniques used for such investigations have highlighted the main pigments used in Roman times for various Roman murals.

Raman Spectroscopy Analysis of the Mural Pigments in Lam Rim Hall of Wudang Lamasery, Baotou Area, Inner Mongolia, China

This paper presents scientific analyses of the wall paintings in Wudang Lamasery, which is located in the Baotou area of Inner Mongolia, China. Raman spectroscopy was used to analyze the pigments of the mural of the Lam rim Hall. The results show that vermilion, red lead, chrome yellow, emerald green and synthetic ultramarine were used. The existence of synthetic pigments provides a clue for the date the mural was painted.

PLS-DA and data fusion of visible Reflectance, XRF and FTIR spectroscopy in the classification of mixed historical pigments

In this work samples of historical pigments of green hue were brushed on a canvas and studied by Visible Reflectance, X-Ray Fluorescence and Fourier Transform Infrared Spectroscopy. One hundred samples were investigated, all with green hue, these prepared from pigments themselves green, such as chromium oxide (Cr₂O₃) or from a mixture of pigments that result in green, for example, chrome yellow (PbCrO₄) and Prussian blue (Fe₄[Fe(CN)₆]₃). Because every sample investigated through the spectroscopic techniques were of green hue, the characterization of the pigments present in the mixtures through the visual inspection of spectra has become a complex task in some cases, also, due the large number of recorded spectra. In this work, classification models were developed using the multivariate statistical method Partial Least Squares Discriminant Analysis (PLS-DA) to automate the characterization of the pigments present in the mixtures. The models were developed to classify chromium oxide (Cr₂O₃), chrome yellow (PbCrO₄), cerulean blue (CoO.nSnO₂) and yellow ochre (Fe₂O₃·H₂O + clay + silica). The models were developed from the fusion of data from the three spectroscopic techniques. However, before data fusion, pre-treatments of the spectral data were tested for their influence on the PLS-DA models. The models developed with data from the three techniques made it possible to classify the pigments of interest in the samples with up to 100% effectiveness. The results also indicate that fusion of the data from the three techniques allows to obtain fingerprints of the pigments of interest, which is not always possible using data from only one or two of the techniques applied in this work.

Chemometric Tools to Point Out Benchmarks and Chromophores in Pigments through Spectroscopic Data Analyses

Spectral preprocessing data and chemometric tools are analytical methods widely applied in several scientific contexts i.e., in archaeometric applications. A systematic classification of natural powdered pigments of organic and inorganic nature through Principal Component Analysis with a multi-instruments spectroscopic study is presented here. The methodology allows the access to elementary and molecular unique benchmarks to guide and speed up the identification of an unknown pigment and its recipe. This study is conducted on a set of 48 powdered pigments and tested on a real-case sample from the wall painting in S. Maria Delle Palate di Tusa (Messina, Italy). Four spectroscopic techniques (X-ray Fluorescence, Raman, Attenuated Total Reflectance and Total Reflectance Infrared Spectroscopies) and six different spectrometers are tested to evaluate the impact of different setups. The novelty of the work is to use a systematic approach on this initial dataset using the entire spectroscopic energy range without any windows selection to solve problems linked with the manipulation of large analytes/materials to find an indistinct property of one or more spectral bands opening new frontiers in the dataset spectroscopic analyses.

A Multi-Analytical Study of Egyptian Funerary Artifacts from Three Portuguese Museum Collections

A diachronic, multi-analytical approach combining EDXRF, µFTIR, µRaman, SEM-EDS, and Py-GC/MS has been adopted with the aim to study for the first time the painting materials used to decorate Egyptian funerary masks and sarcophagi ranging from the Late Period to the Roman Period and stored in the Archaeological National Museum (MNA) and the Carmo Archaeological Museum (MAC) of Lisbon and the Natural History Museum of the University in Oporto (MNH-FCUP). Results indicate that yellow and red ochres, realgar, cinnabar, Egyptian blue, and Egyptian green were used as pigments while chalk served as the preparatory layer. Over the 1000-year timeline of the studied artifacts, the palette remained remarkably consistent with previous findings as exemplified by cinnabar being used for red pigments in samples only dated after the Ptolemaic period. The presence of Sn in Egyptian blue and Egyptian green pigments used in one sample suggests the use of recycled bronze scraps during pigment production. Black pigments in two Late Period masks were found to be produced by mixing Egyptian blue with red ochre suggesting either a hitherto unknown method for production of purple pigments in the Egyptian palette or, alternatively, an attempt to create a specific hue or shade of dark brown or black. The results of this study contribute to further expand the database of Ancient Egyptian painting materials while at the same time helping to valorize three important Egyptian collections in Portugal.

Spectroscopic investigation and comprehensive analysis of the polychrome clay sculpture of Hua Yan Temple of the Liao Dynasty

This article shows the investigation results of the polychrome clay sculptures in Hua Yan Temple of the Liao Dynasty in Datong, China. The mineral pigments, adhesive and painting techniques used in these cultural relics were systematically analyzed in this project. Optical microscope (OM), Scanning electron microscope coupled with an energy-dispersive X-ray spectroscopy (SEM-EDS), micro-Raman, Fourier transform infrared spectrometer (FT-IR) and Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analyses were selected as scientific micro-destructive analytical methods. The results show that the pigments in the polychrome clay sculptures include cinnabar, lead red, malachite, atacamite, azurite, orpiment and gold. Meanwhile, the presence of nitrogen-containing substances and glue-marker characteristic pyrolysis products clearly indicates that the adhesive used in most of the polychrome clay sculptures was glue-protein. Additionally, the combination of heat-bodied tung oil and glue-protein was also found in the golden areas.

The Jacopo Tintoretto "Wedding Feast at Cana": A non-invasive and multi-technique analytical approach for studying painting materials

This paper presents the results of a fully non-invasive photographic and spectroscopic study on a masterpiece by the famous Venetian painter Jacopo Tintoretto (1518-1594): "The Wedding feast at Cana" (1561), located inside the sacristy of the Santa Maria della Salute Basilica in Venice. A restoration campaign was carried out on the painting between 2016 and 2017. Various techniques were chosen to characterize in detail the materials used by the painter, especially pigments: Near Infrared Reflectography (NIR) to identify preparatory sketch and also allowing formulating hypothesis on some pigments; Raman and Fiber Optics Reflectance Spectroscopy (FORS) applied directly to the surface of the object, avoiding sample collection, to identify the pigments palette applied by Tintoretto. Information about binders was also obtained in a totally non-invasive way by using NIR spectroscopy. All analysis points were precisely (±2 mm) registered on a painting virtual map in order to recover them in a future possible conservation project.

Benquerencia (La Serena - Spain) rock art: An integrated spectroscopy analysis with FTIR and Raman

La Serena region is a large plateau with open landscapes bounded in the south by a mountain chain formed by the Benquerencia, Tiros and La Rinconada Sierras. There are more than 300 painted and engraved sites in the region. Cueva Grande, Cueva de En medio and Cueva Pequeña are three Schematic rock art shelters located in the municipality of Benquerencia de la Serena, Badajoz, Spain. Over their panels have been documented more than a hundred of painted schematic figures (anthropomorphic figures, eye-shape figures and symbols) (Neolithic - Copper Age). Paintings are monochromatic with red or black coloration. A total of 13 samples (10 red and 3 black samples) from different panels were collected and analyzed using micro-Raman spectroscopy and ATR-FTIR. Micro-Raman spectroscopy was able to characterize the main mineral component, respectively hematite for the red figures and charcoal for the black paintings. ATR-FTIR was useful to possible ochre and possible organic identification. These latest results are particularly important for understanding manufacturing processes and addressing conservation problems.

Laboratory multi-technique study of Spanish decorated leather from the 12th to 14th centuries

This work comprises an exhaustive study of Spanish decorative leathers dating from the 12th to 14th centuries. These paintings are considered a key example of a crucible of artistic styles: Gothic, Islamic and Florentine Trecento. The goal of this work was to use the scientific information provided by a number of experimental techniques - namely EDX, micro-FTIR, micro-Raman and micro-XRD - to assess the dating of the wooden vault, leather preparation and filling fibres. Another goal was to assess the artistic technique based on the characterization of pigments and the differentiation between original materials and those added throughout its history. Gypsum was the original preparation layer extended over the leather. A new preparation stratum was added in further interventions with the artwork. The original pictorial materials and those used during refurbishments have been identified. Original pigments were: red lead, Mars red, red lake, cinnabar, lapis lazuli, red ochres, raw sienna, white lead and charcoal black. Gilding was also found. Pigments added during restoration were: barite, emerald green, rutile, anatase, Mars red, cadmium red, lithopone, cadmium yellow, charcoal black and orpiment.

Investigation of the Cross-Section Stratifications of Icons Using Micro-Raman and Micro-Fourier Transform Infrared (FT-IR) Spectroscopy

The cross-section stratifications of samples, which were removed from six icons, are studied using optical microscopy, micro-Raman spectroscopy, and micro-Fourier transform infrared (FT-IR) spectroscopy. The icons, dated from the 14th to 19th centuries, are prominent examples of Byzantine painting art and are attributed to different artistic workshops of ​​northern Greece. The following materials are identified in the cross-sections of the icon samples using micro-Raman spectroscopy: anhydrite; calcite; carbon black; chrome yellow; cinnabar; gypsum; lead white; minium; orpiment; Prussian blue; red ochre; yellow ochre; and a paint of organic origin which can be either indigo ( Indigofera tinctoria L. and others) or woad ( Isatis tinctoria L.). The same samples are investigated using micro-FT-IR which leads to the following identifications: calcite; calcium oxalates; chrome yellow; gypsum; kaolinite; lead carboxylates; lead sulfate (or quartz); lead white; oil; protein; Prussian blue; saponified oil; shellac; silica; and tree resin. The study of the cross-sections of the icon samples reveals the combinations of the aforementioned inorganic and organic materials. Although the icons span over a long period of six centuries, the same stratification comprising gypsum ground layer, paint layers prepared by modified "egg tempera" techniques (proteinaceous materials mixed with oil and resins), and varnish layer is revealed in the investigated samples. Moreover, the presence of three layers of varnishes, one at the top and other two as intermediate layers, in the cross-section analysis of a sample from Virgin and Child provide evidence of later interventions.

Multi-analytical methodology to diagnose the environmental impact suffered by building materials in coastal areas

This work is focused on the development of an innovative multi-analytical methodology to estimate the impact suffered by building materials in coastal environments. With the aim of improving the in situ spectroscopic assessment, which is often based on XRF and Raman spectrometers, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was implemented in the diagnosis study. In this way, the additional benefits from DRIFT were compared to the usual in situ analyses of building materials, which often have interferences from fluorescence and reststrahlen effects. The studies were extended to the laboratory scale by μ-X-ray fluorescence (μ-XRF) cross-section mapping and ion chromatography (IC), and the IC quantitative data were employed to develop thermodynamic models using the ECOS-RUNSALT program, with the aim of rationalizing the behavior of soluble salts with variations in the temperature and the relative humidity (RH). The multi-analytical methodology allowed identification of the most significant weathering agents and classification of the severity of degradation according to the salt content. The suitability of a DRIFT portable device to analyze these types of matrices was verified. Although the Kramers-Kronig algorithm correction proved to be inadequate to decrease the expected spectral distortions, the assignment was successfully performed based on the secondary bands and intensification of the overtones and decreased the time needed for in situ data collection. In addition, the pollutants' distribution in the samples and the possible presence of dangerous compounds, which were not detected during the in situ analysis campaigns, provided valuable information to clarify weathering phenomena.

Handheld new technology Raman and portable FT-IR spectrometers as complementary tools for the in situ identification of organic materials in modern art

A non-invasive approach has been carried out to characterize painting materials used in modern artworks conserved in the art collection of Carandente's museum at Palazzo Collicola in Spoleto (Italy). This work is focused on the cross-validation of the handheld BRAVO Raman spectrometer, that uses a sequentially Shifted Excitation (SSE) to mitigate fluorescence, for the characterization specifically of organic materials. The analytical procedure, combining XRF, Raman and reflection infrared spectroscopy, allowed a complete characterization of the artists' palettes; particularly eight different synthetic dyes belonging to the class of pigment red (PR) and pigment yellow (PY.), synthetic and traditional binders, such as alkyd resin and lipids have been easily identified.

Analytical investigation of Mudéjar polychrome on the carpentry in the Casa de Pilatos palace in Seville using non-destructive XRF and complementary techniques

The pigments, execution technique and repainting used on the polychrome wood ceilings and doors in the Casa de Pilatos (Seville, Spain) were studied using portable X-ray fluorescence equipment. Cross-sections of small samples were also analysed by optical microscopy, SEM with EDX analysis, micro-Raman and micro-infrared spectroscopy and X-ray diffraction. These carpentry works are magnificent examples of the Mudéjar art made in Spain in the early 16th century. Portable X-ray fluorescence gave good information on the different components of the polychrome. The SEM-EDX study of the surfaces of small samples gave information on their components and also characterized the compounds that had been deposited or formed by environmental contamination or by the alteration of some pigments. The SEM-EDX study of cross-sections facilitated the characterization of all layers and pigments from the support to the most external layer. The following pigments were characterized: red (cinnabar/vermillion, lead oxide, iron oxides and orpiment/realgar), black (carbon black), white (white lead and titanium barium white), yellow-orange-red-brown (orpiment/realgar and iron oxides), green (chromium oxide), blue (indigo blue and ultramarine blue), and gilding (gold leaf on bole). False gold, bronze and brass were also found. The pigments were applied with the oil painting technique over a support layer that had been primed with animal glue. This support layer was gypsum in some cases and white lead in others. This study is essential to the polychrome conservation of the studied artwork, and it will help clarify uncertainties in the history and painting of Mudéjar art.

Spectroscopic Investigation Leading to the Documentation of Three Post-Byzantine Wall Paintings

The main churches of three monasteries in Thessalia, Central Greece, were decorated with wall paintings in the post-Byzantine period. The main goal of the present study is to characterize the inorganic and organic materials present in the paint layers of areas that have been gilded. Optical microscopic examination was carried out on samples taken from the gilded decoration of the paintings to view their layer build-up. The combined use of micro Fourier transform infrared (FT-IR) and micro-Raman spectroscopy led to the detection of the pigments and the binding media used. The results from specimens taken from different wall paintings were compared with each other to observe their differences and similarities. The three investigated churches are believed to have been painted by the same iconographer, Tzortzis, who however has only been identified in only one of them. The comparison led to the conclusion that there are many similarities in the painting materials used and the general methodology adopted and, therefore, this study offers support to the belief that the mural paintings of the three monasteries could have been painted by the same iconographer. While not authenticating the two painting as being by Tzortzis, the results provide further critical material that is consistent with this attribution. However, this statement must be carefully considered because the pigments identified have been commonly and diffusely used in historic mural paintings.

The efficiency of micro-Raman spectroscopy in the analysis of complicated mixtures in modern paints: Munch's and Kupka's paintings under study

Twenty one mock-up samples containing inorganic pigments primarily used at the turn of the 19th and 20th century were selected for comparative study and measured by micro-Raman and portable Raman spectrometers. They included pure grounds (chalk-based, earth-based and lithopone-based), grounds covered by resin-based varnish, and different paint layers containing mixtures of white, yellow, orange, red, green, blue and black pigments, usually in combination with white pigments (titanium, zinc and barium whites or chalk). In addition, ten micro-samples obtained from seven paintings of two world-famous modern painters Edvard Munch and František Kupka have been investigated. Infrared reflection spectroscopy (FTIR), portable X-ray fluorescence (XRF) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were used as supplementary methods. The measurements showed that blue pigments (ultramarine, Prussian blue and azurite), vermilion and ivory black in mixture with whites provided characteristic Raman spectra, while Co-, Cd- and Cr- pigments' bands were suppressed by fluorescence. The best success rate of micro-Raman spectroscopy has been achieved using the 780 nm excitation, however, the sensitivity of this excitation laser in a portable Raman instrument significantly decreased. The analyses of micro-samples of paintings by E. Munch and F. Kupka showed that micro-Raman spectroscopy identified pigments which would remain unidentified if analyzed only by SEM-EDS (zinc yellow, Prussian blue). On the other hand, chromium oxide green and ultramarine were not detected together in a sample due to overlap of their main bands. In those cases, it is always necessary to complement Raman analysis with other analytical methods.

Analysis of a Brazilian baroque sculpture using Raman spectroscopy and FT-IR

In this study, samples were taken from the sculpture of Our Lady of Sorrows and analyzed by Raman spectroscopy and FT-IR. This sculpture has been dated to the early eighteenth century. Samples were also examined using optical microscopy and Energy Dispersive Spectroscopy (EDS). Based on chemical analysis, the pigments vermilion [HgS], massicot [PbO] and azurite [Cu3(CO3)2(OH)2]were found in the sculpture polychrome. The results indicate that the green polychrome of the sculpture's mantle comes from the blending of massicot and azurite. Because the literature reports that the mantle of the Our Lady of Sorrows sculpture is blue, the mixing of these pigments results from a production error. The results also indicate the presence of Au in the sculpture, which indicates the originality of the piece. The results from this study helped restorers to choose the appropriate procedures for intervening in the sculpture and contributed to the knowledge about the manufacturing process of Brazilian baroque sculptures.

Applicability of a Diffuse Reflectance Infrared Fourier Transform handheld spectrometer to perform in situ analyses on Cultural Heritage materials

This work studies the applicability of a Diffuse Reflectance Infrared Fourier Transform handheld device to perform in situ analyses on Cultural Heritage assets. This portable diffuse reflectance spectrometer has been used to characterise and diagnose the conservation state of (a) building materials of the Guevara Palace (15th century, Segura, Basque Country, Spain) and (b) different 19th century wallpapers manufactured by the Santa Isabel factory (Vitoria-Gasteiz, Basque Country, Spain) and by the well known Dufour and Leroy manufacturers (Paris, France), all of them belonging to the Torre de los Varona Castle (Villanañe, Basque Country, Spain). In all cases, in situ measurements were carried out and also a few samples were collected and measured in the laboratory by diffuse reflectance spectroscopy (DRIFT) in order to validate the information obtained by the handheld instrument. In the analyses performed in situ, distortions in the diffuse reflectance spectra can be observed due to the presence of specular reflection, showing the inverted bands caused by the Reststrahlen effect, in particular on those IR bands with the highest absorption coefficients. This paper concludes that the results obtained in situ by a diffuse reflectance handheld device are comparable to those obtained with laboratory diffuse reflectance spectroscopy equipment and proposes a few guidelines to acquire good spectra in the field, minimising the influence caused by the specular reflection.

Fe(ii)(aq)uptake of Mg(ii)–Al(iii)/Fe(iii)–SO4/CO3HTLCs under alkaline conditions: adsorption and solid state transformation mechanisms

Abiotic reduction of Mg(ii)–Al(iii)/Fe(iii)–SO₄/CO₃hydrotalcites (HTLCs) was investigated under three anoxic abiotic reaction conditions: (1) a target pH of 8 and 10 mM Fe(ii)_(aq), (2) a target pH of 8 and 0.5 mM Fe(ii)_(aq), and (3) a target pH of 10 and 0.5 mM Fe(ii)_(aq).

Solidification/stabilization of toxic metals in calcium aluminate cement matrices

The ability of calcium aluminate cement (CAC) to encapsulate toxic metals (Pb, Zn and Cu) was assessed under two curing conditions. Changes in the consistency and in the setting time were found upon the addition of the nitrates of the target metals. Both Pb and Cu caused a delay in CAC hydration, while Zn accelerated the stiffening of the mortar. Compressive strengths of the metal-doped mortars, when initially cured at 60 °C/100% RH, were comparable with that of the free-metal mortar. Three different pore size distribution patterns were identified and related to the compounds identified by XRD and SEM. Sorbent capacities of CAC for the toxic metals were excellent: a total uptake was achieved for up to 3 wt.% loading of the three metals. In this way, CAC mortars were perfectly able to encapsulate the toxic metals, allowing the use of CAC for waste management as proved by the leaching tests.

Nondestructive identification for red ink entries of seals by Raman and Fourier transform infrared spectrometry

Determination of the red ink entries of seals on documents can provide valuable evidences for solving related crimes, distinguishing the truth of artworks, and so establishment of nondestructive approaches would play a key role in forensic analysis and related aspects. Raman and FT-IR spectroscopy have been applied for analyzing 105 kinds of red ink entries on documents. The dye components of the ink entries were identified by FT-Raman and confocal Raman microspectroscopy, and then the ink entries were classified into four groups based on these dye components. The ink entries were further discriminated by their FT-IR spectra according to adsorption peaks of the main components, the relative intensities of the characteristic bands and the profiles of the spectra. The results showed that 70 ink entries out of 105 have been individually identified and the remaining 35 ink entries can be divided into 13 subclasses. Combination of Raman and FT-IR spectroscopic methods can provide a powerful nondestructive discriminating tool for identification of the red ink entries of seals on papers. These approaches would have potential application in archeology, art and forensic science.

Pigment analyses of a portrait and paint box of Turkish artist Feyhaman Duran (1886-1970): the EDXRF, FT-IR and micro Raman spectroscopic studies

The samples obtained from nine different places of Ataturk portrait (oil on canvas, 86 cm×136 cm) by Feyhaman Duran (1886-1970), one of the famous Turkish painters of the 20th century, together with five pigment samples (two different white, two different yellow and blue), obtained as powders from artist's paint box, were analysed by EDXRF, FT-IR and micro-Raman spectroscopic methods, in order to characterise the pigments used by the artist. Informative Raman signals were not obtained from most of the samples of the portrait, due to huge fluorescence caused by the presence of impurities and organic materials in the samples, however the Raman spectrum of the sample from skin coloured part of the portrait and the pigment samples obtained from the paint box of the artist were found to be very informative to shed light on the determination of the pigments used. Analysis revealed the presences of chrome yellow (PbCrO4), strontium yellow (SrCrO4) and Cadmium yellow (CdS) as yellow, chromium oxides (Cr2O3 and Cr2O3·2H2O) as green, natural red ochre as red, brown ochre as brown and ivory black or bone black (C+Ca3(PO4)2) and manganese oxides (Mn2O3 and MnO2) as black pigments, in the composition of the Ataturk portrait. Lead white (2PbCO3·Pb(OH)2), calcite (CaCO3), barite (BaSO4), zinc white (ZnO) and titanium white (TiO2) were used as extenders to lighten the colours and/or as for ground level painting. Powder pigment samples, obtained from the paint box of artist, were found to be mixed pigments rather than pure ones.

Byzantine wall paintings from Kastoria, northern Greece: spectroscopic study of pigments and efflorescing salts

This study concerns the investigation of pigments and efflorescence phenomena on the wall paintings of Kastoria, a rural, non-metropolitan Byzantine town. A large number of representative samples were collected from the murals of three churches, dated to post-Byzantine era (14th-17th c. AD). The identified pigments for the red colour were hematite (Fe2O3), cinnabar (HgS) and minium (Pb3O4), while brown and yellow colours were attributed to mixtures of ochres (Fe-oxides and hydroxides) and lime. The utilization of admixtures of iron, lead and mercury compounds was also attested in order to render specific tones on the painted surfaces. Black and dark blue hues were prepared using black carbon and Mn in some cases. Grey colours were assigned to a mixture of black carbon and lime. Green colour is rather attributed to admixtures of Fe-rich minerals and lime and not to the commonly used green earths. Baryte (BaSO4) was also evidenced as a filler or extender. Phosphorous was detected and connected to proteinaceous material and Mo and Sb were traced which are probably affiliated to Fe-oxides. Regarding efflorescing salts, the determined compounds are: calcite, dolomite, gypsum, halite, nitratine, natron and mirabilite, all of which are related to temperature and humidity changes and moisture fluctuations inside the wall paintings.

Sulfur isotope analysis of cinnabar from Roman wall paintings by elemental analysis/isotope ratio mass spectrometry--tracking the origin of archaeological red pigments and their authenticity

The most valuable pigment of the Roman wall paintings was the red color obtained from powdered cinnabar (Minium Cinnabaris pigment), the red mercury sulfide (HgS), which was brought from mercury (Hg) deposits in the Roman Empire. To address the question of whether sulfur isotope signatures can serve as a rapid method to establish the provenance of the red pigment in Roman frescoes, we have measured the sulfur isotope composition (δ(34)S value in ‰ VCDT) in samples of wall painting from the Roman city Aventicum (Avenches, Vaud, Switzerland) and compared them with values from cinnabar from European mercury deposits (Almadén in Spain, Idria in Slovenia, Monte Amiata in Italy, Moschellandsberg in Germany, and Genepy in France). Our study shows that the δ(34)S values of cinnabar from the studied Roman wall paintings fall within or near to the composition of Almadén cinnabar; thus, the provenance of the raw material may be deduced. This approach may provide information on provenance and authenticity in archaeological, restoration and forensic studies of Roman and Greek frescoes.