Search

Although many prominent artists have experimented with pastels, this technique has been the subject of very limited scientific research. The first known recipes of pastels date back to the 16th century, but only during the 18th century did the pastel technique become more common. Identifying and characterising the organic constituents in pastels materials is challenging given that they are present in extremely low concentrations and could be produced using many organic substances, whose chemical composition alters during ageing. The chemical-physical behaviour of organic media in artworks is often crucial in causing the degradation problems, which need to be addressed by conservation. We evaluated the applicability of an analytical approach based on chromatography and mass spectrometry to investigate the composition of the pastels used by Umberto Boccioni in a drawing dated 1908 and conserved at the Museo del Novecento in Milan (Italy). The investigation of the formulation of artists’ pastels used in the first decade of the 20th century is particularly important in order to improve the knowledge of this technique. The analysis highlighted the presence of proteins and plant gums in the artwork samples, with differences in the composition for the different samples.

In this work, we propose the laser-based cleaning with a Q-switched Nd:YAG laser (λ = 532 nm) not as a standalone methodology but rather in combination with chemical agents for the efficient removal vandal signs made with spray paints from marble substrates. The advantage of such approach is based on the preliminary removal of the superficial paint by pulsed laser radiation so as to minimize the risk of the further colorant diffusion in the stone, caused by the solvent-based cleaning that is performed in the second step. The outcome was demonstrated on the removal of five aerosol paints (red, blue, black, green and yellow by Montana Colors 94), whose typology was chosen in agreement with the widespread use of this brand. The influence of substrate characteristics on the cleaning performance, such as roughness, porosity, and ageing of the paint, was investigated on fresh and aged paints on sound marble as well as on fresh paints on aged marble. Fresh and aged paints were characterized in terms of mineralogy and chemistry using X-ray diffraction (XRD), X-ray fluorescence (XRF), Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS), Gas/Chromatography/Mass spectrometry (GC/MS). The efficiency for single cleaning step and when applied in sequence was evaluated by colorimetric measurements, optical microscopy on surface and in cross section, XRF and reflection Fourier Transform Infrared spectroscopy (FTIR). Invasiveness of laser cleaning on sound marble was evaluated by Laser Scanner microprofilometry. The results converge in indicating the combined approach as a promising method where the preliminary thinning of the paint layer with laser ablation and the subsequent solvent action proved more efficient than the standalone approaches. The dependence of cleaning efficiency on the paint composition and ageing, as well as on the porosity of the stone, is also discussed.

“Composizione-Superficie Lunare” (1965) is an artwork of the Italian artist Giulio Turcato (Mantua, 1912- Rome, 1995). This painting, inspired by moon travels, was created on a polyurethane foam support, material experimentalized by some other contemporary artists in the late 1960′s. In the present paper the organic and inorganic materials used as binders, fillers and pigments, as well as the support itself, have been investigated by means of a multi-analytical approach based on the application of Environmental Scanning Electron Microscopy Energy-Dispersive X-ray spectroscopy (ESEM–EDX), Micro-Attenuated Total Reflection Fourier Transform Infrared spectroscopy (µ-ATR–FTIR), High Performance Liquid Chromatography coupled with Diode Array Dectector and tandem Mass Spectrometry (HPLC–DAD, LC–MS/MS), Pyrolysis-Gas Chromatography and Evolved Gas Analysis coupled with Mass Spectrometry (Py-GC/MS, multi-shot Py-GC/MS and EGA–MS). The plethora of analytical techniques available allowed to provide for the first time a full characterization of the different materials used in “Composizione-Superficie Lunare” and of a Turcato's painting. The polyurethane foam artwork was painted using synthetic inorganic and organic pigments, such as methyl violet and manganese violet, dispersed in polyvinyl acetate as medium. The study was fundamental for establishing the original materials and aesthetics of the artwork as well as assessing the degradation state of the painting materials and of the polyurethane foam support. The results collected, crucial for planning an effective restoration campaign, highlight the importance of the contribution of analytical chemistry to cultural heritage.

Green pigments in micro-samples taken from three late-medieval painted objects from Norwegian churches have been investigated with the aim to characterize their constituents and understand how they relate to damages observed in passages containing green paints. The cross-sections were analyzed by optical microscopy under visible and UV light, Scanning Electron Microscopy coupled with Energy Dispersive X-Ray Spectrometry and vibrational spectroscopies (Raman, ATR-FTIR). In addition, Gas Chromatography coupled with Mass Spectrometry was employed for the characterization of binding media, using a derivatization methodology recently developed for the detection of metal soaps in paint samples. This extensive characterization aided the identification of the individual constituents and the stratigraphy of green paints. It also builds the foundation for future ageing studies that can provide better insights into the mechanisms of the processes at stake in selective delamination of paints containing copper complexes.

Metal soaps and resinates are known to be spontaneously formed in artistic paintings, as a product of the reaction between aliphatic and terpenoid acids released by hydrolysis and oxidation of the organic media and certain cations contained in some inorganic pigments. In this paper we present an optimization and the validation of a GC/MS method for the qualitative and quantitative analysis of mixtures of terpenoid acids and aliphatic mono and dicarboxylic acids and metal carboxylates of terpenoid and aliphatic mono and dicarboxylic acids in the same paint microsample. This is based on a two-step analytical approach entailing the subsequent use of two silylating agents, N,O-bis(trimethylsilyl)trifluoroacetamide for the analysis of free acids and metal carboxylates, and 1,1,1,3,3,3-hexamethyldisilazane for the analysis of free acids. The application of this approach is possible because of the good stability at room temperature of the TMS derivatives of aliphatic and terpenoid species, characterized by high boiling points and relatively low vapour pressures. The method was then applied to the characterization of samples collected from two reference paint layers aged for 20 years, a paint sample taken from a pulpit, and sample of the varnish coating of a wooden writing desk, both from the second half of the seventeenth century.

We investigated the cedar wood doors of the Bahia Palace in Marrakesh (Morocco), which are richly decorated with geometric motifs. A gas chromatographic mass spectrometric analytical procedure (GC/MS) was used to characterize the organic binders in micro samples collected from one of the doors. In order to examine the artist's palette, X-ray fluorescence (XRF), Raman and Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC-DAD), were applied to samples in fragments or on cross-sections of the embedded samples. This multi analytical approach effectively identified the polychrome decoration technique, mainly based on the use of animal glue as a proteinaceous binder, and characterized the superficial varnishes. Lastly many of the different pigments used for the creation of these works of art were identified. We believe that this study contributes significantly to the knowledge of Moroccan art from a material and technological point of view.

ConspectusThe 20th and 21st century oil paintings are presenting a range of challenging conservation problems that can be distinctly different from those noted in paintings from previous centuries. These include the formation of vulnerable surface “skins” of medium and exudates on paint surfaces, efflorescence, unpredictable water and solvent sensitivity, and incidence of paint dripping which can occur within a few years after the paintings were completed.Physicochemical studies of modern oil paints and paintings in recent years have identified a range of possible causal factors for the noted sensitivity of painting surfaces to water and protic solvents, including the formation of water-soluble inorganic salts and/or the accumulation of diacids at the paint surface, which are oxidation products of the oil binder. Other studies have investigated the relationship between water sensitivity and the degree of hydrolysis of the binder, the proportions of free fatty and dicarboxylic acids formed, as well as the relative content of free metal soaps. Thus far, data indicate that the qualitative and quantitative composition of the nonpolymerized fractions of the oil binder cannot be solely or directly related to the solvent sensitivity of the paint film. Conclusions therefore indicate that the polymeric network, formed upon the curing of the oil, plays a fundamental role, suggesting that water sensitivity, at least in some cases, may be related to the poor development and/or polar nature of the formed polymeric network rather than the composition of the nonpolymerized fractions.Poorly developed polymeric networks, in combination with the migration of polar fractions, i.e., dicarboxylic and hydroxylated fatty acids toward the paint surface, can be related to other degradation phenomena, including the separation and migration of the paint binder which can lead to the presence of observable skins of medium as well as the more alarming phenomenon of liquefying or dripping oil paints. It is thus crucial to understand the molecular composition of these paints and their physicochemical behavior to aid the further development of appropriate conservation and preservation strategies, as the risks currently associated with surface cleaning treatments and other conservation procedures can be unacceptably high.This Account reviews the relationships between the degradation phenomena associated with modern oil paintings and the chemical composition of the oil binder and proposes a molecular model for the development of water sensitivity and other noted degradation phenomena. It is suggested that water sensitivity (and possibly other degradation phenomena) is a consequence of processes that take place upon curing, and in particular to the rate of formation and decomposition of alkoxyl and peroxyl radicals. These reactions are strongly dependent on the type of oil present, the ambient environmental conditions, and the chemical and physical nature of the pigments and additives present in the paint formulation. When the curing environment is oxidizing, the chemistry of peroxyl radicals dominates the reaction pathways, and oxidative decomposition of the paint film overwhelms cross-linking reactions.

In this paper we present a new analytical GC/MS method for the analysis of mixtures of free fatty acids and metal soaps in paint samples. This approach is based on the use of two different silylating agents: N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1,1,1,3,3,3-hexamethyldisilazane (HMDS). Our experimentation demonstrated that HMDS does not silylate fatty acid carboxylates, so it can be used for the selective derivatization and GC/MS quantitative analysis of free fatty acids. On the other hand BSTFA is able to silylate both free fatty acids and fatty acids carboxylates. The reaction conditions for the derivatization of carboxylates with BSTFA were thus optimized with a full factorial 32 experimental design using lead stearate and lead palmitate as model systems. The analytical method was validated following the ICH guidelines. The method allows the qualitative and quantitative analysis of fatty acid carboxylates of sodium, calcium, magnesium, aluminium, manganese, cobalt, copper, zinc, cadmium, and lead and of lead azelate. In order to exploit the performances of the new analytical method, samples collected from two reference paint layers, from a gilded 16th century marble sculpture, and from a paint tube belonging to the atelier of Edvard Munch, used in the last period of his life (1916–1944), were characterized.

The most common synthetic carbon-based black pigments can be divided into three main groups on the basis of the material used for their production: bone blacks, vine blacks and lampblacks. This work reports on the physicochemical characterization of the three commercial pigments purchased from Kremer Pigmente (Germany) and Zecchi (Italy) by means of a multi-analytical approach, which included thermoanalytical (thermogravimetry, thermogravimetry coupled with FTIR and differential scanning calorimetry) and spectroscopic techniques (laser-induced breakdown spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy and X-ray powder diffraction). Combining the results obtained from this multi-analytical approach, qualitative and quantitative conclusions are drawn for the first time. Lampblacks are mainly composed of amorphous carbon. In vine black (Kremer), amorphous carbon and cellulose pyrolysis by-products are the main constituents. In bone blacks and vine black (Zecchi), carbonaceous materials are minor components. Hydroxyapatite and calcium carbonate are the main constituents of bone blacks, and iron and magnesium oxides are the main constituents of vine black (Zecchi). Results from this multi-analytical study on the composition of such widespread pigments can provide valuable information in the decision-making process for restorers and conservators.

A series of Burmese lacquered objects decorated with the yun (incised) technique and belonging to the British Museum’s collection was analysed with the aim to investigate the decorative materials—lacquer, binding media, additives and pigments—used in the production of these objects, which span chronologically from the eighteenth century to the late twentieth century. As the manufacturing process is supposed to have remained very similar over this time period, especially regarding the use of materials, we were interested in scientifically assessing for the first time the nature of these materials and the correspondence to the written sources in the relation to their specific use. Gas chromatography mass spectrometry (GC–MS) and analytical pyrolysis with in situ silylation coupled with GC–MS (Py(HMDS)GC–MS) were used for the identification of the organic components in several samples taken from the coloured areas of the objects. Fibre optic reflectance (FORS) and Raman spectroscopies were used to identify the pigments after a visual investigation of the samples by digital microscopy. Burmese lacquer was detected in all objects and trends in its degradation were highlighted. Lipids, proteins and saccharide material were found to be mixed with lacquer, and they appeared to be applied with specific pigments, in good agreement with the written records, apart from proteins, which are not mentioned. The use of synthetic pigments, such as phthalocyanines blue and green and chrome yellow, was assessed in the most recent objects, showing an evolution in the use of pigments. Indigo, although expected, was not identified in any of the green samples and Prussian blue appeared to be the main source of blue colour. All this information is of fundamental importance for conservation practices and corrects the general opinion about the production materials of these objects. These results also open the way to future research dedicated to exploring the chemical interaction between Burmese lacquer, proteins, lipids, gums and pigments, with the aim to predict possible differences in degradation pathways.

Identification of proteins in paintings and polychrome objects is a challenge, which requires the development of tailored analytical approaches. In the present study, a targeted proteomics approach was developed for discriminating among the three most common proteinaceous materials used as paint binders, i.e. milk, egg, and animal glue. In this study a specific database of peptides was created based on tandem MS analyses of tryptic digests of several paint samples collected from a variety of art objects of different ages and conservation conditions. Specific peptide markers of each protein were then selected and monitored by LC-MSMS in Multiple Reaction Monitoring (MRM) ion mode, together with their specific precursor ion-product ion transitions, as defined by their unique amino acid sequence. The developed method enabled a sensitive and reliable detection of the target peptides in a selection of case studies, leading to the unambiguous identification of the proteins used as paint binders. The method showed greatly increased sensitivity compared to currently available strategies.

International audience; The huge number of complex formulations of synthetic dyes and pigments commercialized in the 19th century makes their comprehensive characterization both difficult and fundamental for their successful identifications in artworks. The description of the exact starting composition of a wide collection of reference materials is preliminary to the study of the challenging photo-degradation processes in which most of the early synthetic dyes and pigments are involved. In this paper, four eosin-based lakes, all containing eosin Y, and one also containing eosin B, but differing in the organic and inorganic materials used as fillers, were fully characterized. These formulations were reconstructed on the base of historical recipes from the extensive Wiesel's collection, dated to the 19th century and bought by Dr Kremer (Kremer Pigmente, Germany) in the 1990s. The composition of each formulation was characterized by Fourier transform infrared spectroscopy (FT-IR) and luminescence spectroscopy was used as a probe for their inert-distinction. Reference paint layers were then prepared by casting the lakes in linseed oil, and their ageing and impact on color change was monitored for one year by analyzing two sets of paint model systems by colorimetry. For each system, two sets were prepared and one was stored in the dark while the other exposed to natural light. The material distribution and homogeneity of the samples were tested by Synchrotron Radiation based micro infrared spectroscopy (SR-μ-FT-IR). Finally, an ultra-sensitive method based on Liquid Chromatography coupled with High Resolution Mass Spectrometry (LC-HRMS) allowed us to characterize eosin degradation products detected but never identified before, and to evaluate their kinetics of formation.

In this work, an innovative sampling and preconcentration method followed by analysis with liquid chromatography coupled to tandem mass spectrometry with electrospray ionization (LC-ESI-MS/MS) was developed for the determination of different emerging pollutants (five anti-inflammatory drugs and one antibacterial agent) in water matrices. Thin-film microextraction blades, consisting of stainless steel blades with a coating made of divinylbenzene, have been employed. The blades, fixed onto a stainless steel support, were mounted on a laboratory stirrer with adjustable speed, immersed in water samples and eluted with methanol. The analytical procedure was developed, carefully optimizing stirring speed and extraction time. A good reproducibility among the blades was observed; quantitation limits at the ng L-1 level were achieved. Calibration curves were constructed by applying the whole procedure to tap water samples, free from analytes, spiked with standards in the concentration range 0.01-2 μg L-1 ; good linearity was obtained, with R2 between 0.9984 and 0.9991. The optimized method was applied to tap and surface waters; two anti-inflammatory drugs were detected at the ng L-1 level in surface water. In one sample, diclofenac and naproxen were measured at 26 ± 5 and 15 ± 1 ng L-1 , respectively; only diclofenac was quantified in the other sample at 14 ± 3 ng L-1 .

The identification of the organic material used in the polychrome decorations of Alhambra complex was carried out in this investigation. Samples from motifs painted on different types of supports, namely marble, wood, and gypsum, were studied. In this way, a comparison on the organic materials used in the marble capitals of the columns from different sites (Hall of the Abencerrages, Hall of the Mexuar, The Court of the Myrtles and the Court of the Main Canal), the Nasrid polychrome wooden ceilings of the Hall of the Abencerrages and the gypsum mocarabes in the plaster decorations of the Hall of the Kings was achieved. This is the first wide scientific study regarding the organic materials employed in the execution of the most representative decorative revetments in the Alhambra monument. Despite the small amount of sample and the complex history of interventions in the monument (both documented and not), results obtained with GC-MS show that proteinaceous materials were mainly used as binders in the different supports and periods studied being animal glue identified in almost all cases. Moreover, wax and lipid materials were also found in the samples from the ceilings, probably as restoration materials applied on the surface of the polychromes on wood. These results shed light on the painting techniques in this extraordinary example of Muslim art in its final European stages, thus contributing to provide scientific information about the still little studied medieval Islamic art.

Understanding the original techniques in the creation of an artwork is a prerequisite for the selection of the most appropriate conservation method. This is particularly essential in wall paintings where control of potential agents of deterioration and efficient monitoring are limited due to the scale of the paintings and their exposure to uncontrollable environmental fluctuations. Analytical studies are increasingly focused on the investigation and study of degradation products of organic binders originally added in the paintings on a lime-based plaster ground. In the framework of IPERION-CH (Integrated Platform for the European Research Infrastructure ON Cultural Heritage) project, a collaborative task is dedicated to obtain knowledge about original organic materials used in wall paintings by evaluating and comparing different innovative methodologies and conventional diagnostic techniques used for the investigation of markers related to alteration mechanisms and degradation products. The non-invasive and microsampling methodology is first optimized on well-defined models that have been designed to simulate different painting techniques with limewater and five organic binders in different relative proportions. Future investigations will focus on the application of the optimized methodology on archaeological samples. In the present paper, preliminary results on a selected set of models, submitted in different stages of a well-established artificial ageing protocol, demonstrate the specific complementary input of each analytical technique included in the analytical approach (colour measurements, micro FTIR-ATR analyses in cross-sections, Evolved Gas Analysis-Mass Spectrometry and Gas Chromatography-Mass Spectrometry). The comparative evaluation and interpretation of the results is a step forward in the optimization of the approach and in relating the analytical findings detected on the analysed samples to the original compounds and the possible changes for each group of binders (proteins/gums) due to degradation or interaction depending on the pigment/metal ion present.

open 17 si The composition of the ancient wax-based painting technique known as encaustic has long been the subject of debate. Ancient sources provide few details of the technology, and modern understanding of the medium is restricted to theoretical interpretation and experimental observation. In this multi-analytical collaborative study, a number of analytical approaches were used to investigate the physical and molecular properties of a range of experimentally prepared encaustic paints before and after ageing. Analysis using gas chromatography mass spectrometry, Fourier transform infrared spectroscopy (invasive and non-invasive), X-ray diffraction and thermogravimetric analysis demonstrated how differences in the technology of production alter the properties and composition of the medium and showed how these are modified by the addition of pigment and the effects of ageing. Comparison of results from the different analytical techniques highlights the benefit of an integrated analytical approach to the analysis of ancient encaustic paints and the fundamental importance of insights from invasive study to evaluating the results of non-invasive analysis. open Stacey, R.J.*; Dyer, J.; Mussell, C.; Lluveras-Tenorio, A.; Colombini, M.P.; Duce, Celia; La Nasa, Jacopo; Cantisani, Emma; Prati, S.; Sciutto, G.; Mazzeo, R.; Sotiropoulou, S.; Rosi, F.; Miliani, C.; Cartechini, L.; Mazurek, J.; Schilling, M. Stacey, R.J.*; Dyer, J.; Mussell, C.; Lluveras-Tenorio, A.; Colombini, M.P.; Duce, Celia; La Nasa, Jacopo; Cantisani, Emma; Prati, S.; Sciutto, G.; Mazzeo, R.; Sotiropoulou, S.; Rosi, F.; Miliani, C.; Cartechini, L.; Mazurek, J.; Schilling, M.

This work proposes a multi-analytical approach to determine the additives in historical mortars, the use of which is widely described in bibliographical sources, but has rarely been reported in the literature. A protocol to thoroughly analyse mortars was created (optical microscopy, X-ray diffraction, infrared spectroscopy, thermal analyses and gas chromatography – mass spectrometry). These techniques had already been carried out on samples from various sites from the Roman to the modern era, finding that additives had only been used in the mortars from the internal masonry at our sampling site: the medieval military shipyard of Amalfi (Italy). The investigations yielded information on the production technology, and FT–IR and GC–MS revealed a saccharide material-based additive in the mortars, of plant origin. The FT–IR spectra suggested the presence of a natural gum, which has been used since ancient times to strengthen the cohesion properties of mortars and their resistance to tensile stress

The present work reports decisive new data regarding the characterization of the paint materials used by Cypriot icon painters in Orthodox icons from the 12th to the 18th century. Eight samples of red paint, collected from seven different icons originally placed in three different churches in Morphou and Nicosia (Cyprus) have been analysed to identify the painting technique. The identification of pigments and fillers was performed using micro-Raman spectroscopy and Fourier Transform Infrared spectroscopy (FT-IR). In order to determine the binding medium, Pyrolysis Gas Chromatography-Mass Spectrometry (Py/GC/MS) and Gas Chromatography-Mass Spectrometry (GC/MS) were used. The study of the organic colorants was performed by Liquid Chromatography-tandem Mass Spectrometry (LC-MS/MS) analysis. Both inorganic pigments and organic colorants were used to create the red hues in the icons. Cinnabar was identified in almost all the paint samples studied, although in some cases red lead was also found. European cochineal, kermes, redwood and Indian lac were identified in the red paints, in combination with inorganic pigments. Moreover, stratigraphic analyses allowed us to assess that animal glue and calcium sulphate were used for the preparation layers, while egg was used as binding medium in the red paint layers. The identification of Indian lac in a 12th century icon is the first known occurrence reported in the literature of this organic colorant in the European tradition.

A chemical investigation of the organic paint binders of the Giant Buddhas of Bāmiyān was performed using an analytical approach based on mass spectrometry, combining traditional gas chromatography/mass spectrometry protocols with advanced proteomics methodologies. The research was carried out on a selection of rescued fragments. The data revealed the use of egg proteins as the paint binders of the original layers, in accordance with the traditional use of this proteinaceous medium in antiquity, spanning from the Mediterranean basin to the Far East, and already in the Bronze Age. Egg tempera was thus known to artists of the region in the first centuries AD, probably also due to the position of the Bāmiyān valley, which was connected to the Silk Road. Milk was found in the first historical overpaintings. A new proteomics approach was used, which was able to identify the source of the milk proteins present in the restoration layers, despite their age and degradation. In particular cow's and goat's milk were both found, in agreement with the documented presence of rich pastures in the Bāmiyān valley when the historical restorations were carried out. Investigating the materials of the Giant Buddhas not only enabled us to obtain isolated data on these invaluable works of art, which are now lost, but contributes to understanding the big ªpuzzleº of our past and the development of our culture, by implementing and supporting written sources, stylistic and anthropological studies with molecular data.

International audience; Mixtures of siccative oil and Pinaceae resin were among the most widespread formulations used for varnishing in the 16th–18th centuries. The aim of this research is to study the molecular composition of different formulations of varnishes based on linseed oil and colophony. The mixtures were prepared by cooking both raw materials in different proportions, following the outlines of historical recipes gathered in treatises and manuscripts from that period. Size exclusion chromatography (SEC) evidenced the presence of numerous oligomeric compounds from linseed oil and colophony. Analysis using Electrospray-Quadrupole-Time of Flight mass spectrometer (ESI-Q-ToF) allowed the characterization of oligomeric compounds from colophony. In particular, structures of dimeric diterpenic acid units attached by ester, ether, anhydride or keto linkage are proposed. Concerning linseed oil, oxidized and chain-shortened triglycerides were characterized with High Performance Liquid Chromatography coupled with Electrospray-Quadrupole-Time of Flight mass spectrometer (HPLC–ESI-Q-ToF). SEC quantitation of compounds allowed us to assess the influence of the oil to colophony ratio on the molecular composition of the varnishes: oil polymerization appears to be minimized in favor of its hydrolysis in presence of colophony, whereas linseed oil seems to inhibit the formation of diterpenic dimers and trimers. In addition, analyses evidence the reaction of diterpenic acids with linseed oil compounds. In particular, we identified hybrid molecules formed by a diglyceride and a diterpenic acid. Addition products of a of a triglyceride and a diterpenic acid may also be present in the mixtures. These results bring new information about the molecular composition of varnishes made from linseed oil and colophony, and will improve the knowledge of historical varnishes. To this purpose, all analytical protocols were implemented on micro-samples so that they could be applied later on ancient artifacts.

This study deals with the identification of anthraquinoid molecular markers in standard dyes, reference lakes, and paint model systems using a micro-invasive and nondestructive technique such as matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI-ToF-MS). Red anthraquinoid lakes, such as madder lake, carmine lake, and Indian lac, have been the most widely used for painting purposes since ancient times. From an analytical point of view, identifying lakes in paint samples is challenging and developing methods that maximize the information achievable minimizing the amount of sample needed is of paramount importance. The employed method was tested on less than 0.5 mg of reference samples and required a minimal sample preparation, entailing a hydrofluoric acid extraction. The method is fast and versatile because of the possibility to re-analyze the same sample (once it has been spotted on the steel plate), testing both positive and negative modes in a few minutes. The MALDI mass spectra collected in the two analysis modes were studied and compared with LDI and simulated mass spectra in order to highlight the peculiar behavior of the anthraquinones in the MALDI process. Both ionization modes were assessed for each species. The effect of the different paint binders on dye identification was also evaluated through the analyses of paint model systems. In the end, the method was successful in detecting madder lake in archeological samples from Greek wall paintings and on an Italian funerary clay vessel, demonstrating its capabilities to identify dyes in small amount of highly degraded samples. Graphical Abstract ᅟ.

Eosin is a xanthenic synthetic organic dye/pigment synthesized by Caro in 1873. It was precipitated with lead and aluminum salts and commercialized as geranium lake and it was one of the most brilliant hues in the palette of the Impressionist painter Vincent van Gogh. Unfortunately, the high photosensitivity of eosin has caused the evident fading of the intense pink colorations of his canvas paintings into lighter ones. This work aims at underlying the contribution of several complementary different analytical techniques in disclosing a very complex and still little-known topic such as the degradation process of eosin.

Micro-Raman spectroscopy, pyrolysis/gas chromatography–mass spectrometry (Py/GC/MS) and gas chromatography-mass spectrometry (CG/MS) were applied for the characterization of pigments and binders used in the wall paintings ascribed to the works of the prominent 19th century Macedonian iconographer, Dicho Zograph. Among numerous works attributed to him, wall paintings from three churches in the Western part of the Republic of Macedonia have been selected for pigment and binder analysis. A rich palette of pigments, both natural/mineral and synthetic ones, were identified by micro-Raman spectroscopy. Organic material analysis evidenced the use of mixtures of proteinaceous materials (mainly animal glue and egg) with linseed oil and pine resin, while saccharide materials were excluded. A comparison between the pigments and binders identified in this study and those suggested in Dicho's Painter's Manual (from 1851) showed that some materials had not been mentioned in his written source. Copyright © 2012 John Wiley & Sons, Ltd.

This paper describes a method for reliably identifying saccharide materials in paintings. Since the 3(rd) millennium B.C., polysaccharide materials such as plant gums, sugar, flour, and honey were used as binding media and sizing agents in paintings, illuminated manuscripts, and polychrome objects. Although it has been reported that plant gums have a stable composition, their identification in paint samples is often doubtful and rarely discussed. Our research was carried out independently at two different laboratories: the Getty Conservation Institute in Los Angeles, USA (GCI) and the Department of Chemistry and Industrial Chemistry of the University of Pisa, Italy (DCCI). It was shown in a previous stage of this research that the two methods give highly comparable data when analysing both reference paint samples and paint layers from art objects, thus the combined data was used to build a large database. In this study, the simultaneous presence of proteinaceous binders and pigments in fresh and artificially aged paint replicas was investigated, and it highlighted how these can affect the sugar profile of arabic, tragacanth, and fruit tree gums. The environmental contamination due to sugars from various plant tissues is also discussed. The results allowed the development of a new model for the reliable identification of saccharide binders in paintings based on the evaluation of markers that are stable to ageing and unaffected by pigments. This new model was applied to the sugar profiles obtained from the analysis of a large number of samples from murals, easel paintings, manuscripts, and polychrome objects from different geographical areas and dating from the 13(th) century BC to the 20(th) century AD, thus demonstrating its reliability.

An organic binder was identified in the painted fragments from the Canaanite palace of Tel Kabri, Israel. Recently dated to the late 18th century B.C.E. by 14 C, Tel Kabri is the most ancient of the Eastern Mediterranean sites in which Aegean style paintings have been found. The application of pigments was suspected to be using an organic binding medium, particularly for the Egyptian Blue pigment. Samples of blue paint were examined using evolved gas analysis-mass spectrometry (EGA-MS) in order to overcome the analytical challenges imposed by highly degraded aged proteinaceous materials. Egg was identified as the binder based on the presence of hexadecanonitrile and octadecanonitrile, confirming the use of a secco painting technique. Lysozyme C from Gallus gallus was detected by proteomics analysis, confirming the presence of egg. To our knowledge, this is the earliest use of egg as a binder in Aegean style wall paintings.