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“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.

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.

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.

In this paper we present the technical study of protein-drying oil mixtures in the paint formulation of original manufacturers paint tubes from Fabbrica di colori per Belle Arti Maimeri dating back to the 1950s. The study is part of a wider research project aimed at understanding the chemistry of protein-drying oil mixtures, and how the oil curing in the presence of proteins may affects the protein analysis with mass spectrometric based techniques. Tempera grassa, according to traditional Late Medieval and Renaissance painting techniques, entails the use, as paint binder, of a mixture of a drying oil with a water miscible medium, commonly egg. The paints analysed in this study were, according to technical documentation available at the manufacturer, based on a mixture of linseed oil, ovalbumin and mastic resin. All the components of the paints were detected but proteins proved very challenging. They could not be detected by pyrolysis coupled to gas chromatography-mass spectrometry, nor by using classical procedures for gas chromatography – mass spectrometry analysis of amino acids after hydrolysis. A new analytical procedure based on two subsequent hydrolysis steps assisted by microwaves was implemented and proved to be successful. The first step with trifluoroacetic acid was aimed at a partial hydrolysis of proteins into peptides, for their efficient extraction. The second with hydrochloric acid in the vapour phase was used for a complete hydrolysis of peptides into amino acids for the GC–MS analysis. Linking experimental results on the tempera grassa paints to data obtained on the curing of oil/protein mixtures in paint mock-ups, the hypothesis that copolymerisation of proteins and the oil has taken place is proposed, and a discussion on how this may affect protein detection is carried out.

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.

The influence of free metal stearates, other metal soaps and free fatty acids on the water sensitivity of modern oil paint swatches from three brands of artists’ manufactured tube paints was investigated. The swatches produced in 2006 and tested for water sensitivity in 2008 were re-tested, and changes in sensitivity were recorded. Swatches with a range of sensitivity to water and those that exhibited visible surface deterioration were selected for chemical and optical characterisation. This included a novel method of sample preparation for gas chromatography coupled with mass spectrometry (GC/MS) for quantitative analysis of free fatty and dicarboxylic acids and related metal soaps. Results suggested that the proportion of free fatty acids and metal soaps in the swatches does not relate to water sensitivity of the paint surface. It is therefore likely that the polymeric/ionomeric network plays an important role in water sensitivity. Results showed that fatty acid efflorescence is linked with high levels of free fatty acids (FFA) in the paint swatch and that the extent of the efflorescence is proportional to the quantitative results for free fatty acids found in the GC/MS analyses.

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.

This paper outlines the approach and key findings of systematic studies into the use of various surface cleaning materials on a range of accelerated-aged sensitive oil paint surfaces, carried out through the Cleaning Modern Oil Paints (CMOP) project. Studies involved the use of recently introduced options such as adjusted pH and conductivity waters, spreadable gels, rigid gels, silicone emulsifiers, and mineral spirits-based microemulsions, with additional explorations into the effects of application methods. The evaluation methodology encompassed star diagrams designed to capture observations made during cleaning tests, and paint surface evaluations using digital microscopy, colour and gloss assessment, and ATR-FTIR analysis. In most cases, the most promising free solvents were subsequently incorporated into spreadable and rigid gels, water-in-oil microemulsions and silicone emulsions, tailoring the approach to further minimise undesirable effects where possible. Cleaning system residues were also investigated using visual inspection, microscopy and ATR-FTIR analysis, with a selection of samples further investigated using a pyrolysis on-line micro-reaction sampler and XPS analysis. The combined results offer information on the advantages and risks associated with each cleaning material, and an approach to optimising wet systems for the cleaning of sensitive oil painted surfaces.

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 .

For more than a century, the analyses of painting fragments have been carried out mainly through the preparation of thick resin-embedded cross-sections. Taking into account the development of innovative micro-analytical imaging techniques, alternatives to this standard preparation method are considered. Consequently, dedicated efforts are required to develop preparation protocols limiting the risks of chemical interferences (solubilisation, reduction/oxidation or other reactions) which modify the sample during its preparation, as well as the risks of analytical interferences (overlap of detected signals coming from the sample and from materials used in the preparation). This study focuses particularly on the preparation of thin-sections (1–20 μm) for single or combined fourier transform infrared (FTIR) spectroscopy and X-ray 2D micro-analysis. A few strategies specially developed for the μFTIR analysis of painting cross-sections have already been reported and their potential extrapolation to the preparation of thin-sections is discussed. In addition, we propose two new specific methods: (i) the first is based on a free-embedding approach, ensuring a complete chemical and analytical neutrality. It is illustrated through application on polymeric design objects corpus; (ii) the second is based on a barrier coating approach which strengthens the sample and avoids the penetration of the resin into the sample. The barrier coating investigated is a silver chloride salt, an infrared transparent material, which remains malleable and soft after pellet compression, enabling microtoming. This last method was successfully applied to the preparation of a fragment from a gilded Chinese sculpture (15th C.) and was used to unravel a unique complex stratigraphy when combining μFTIR and μXRF.

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.

An analytical approach based on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectrometry (GC/MS) was used to characterize Egyptian embalming materials from the University of Florence's (Italy) Natural History Museum. FTIR was used as a fast fingerprinting tool due to its ability to characterize inorganic compounds and to highlight different classes of organic materials. GC/MS following alkaline hydrolysis, solvent extraction, and trimethylsilylation was used to determine the molecular nature of organic materials and their degradation products. The results show that the embalming materials consisted of complex mixtures of natural products as well as transformation products due both to natural ageing and human interventions. FTIR analyses, along with evidence of organic materials, enabled us to identify the presence of calcium oxalates, phosphates and carbonates, while XRD patterns confirmed the crystalline nature of both phosphates and oxalates. On the basis of the GC/MS identification of specific profiles of long-chain fatty acids, long-chain alcohols and alkanes, polycyclic terpene hydrocarbons and diterpenes, and triterpenes, we found that the balms of the mummies mainly consisted of beeswax, pine pitch and mastic resin. Ricinoleic acid suggests that castor oil was used as an ingredient in the mummification balm in three of the samples. The combination of results allowed the identification of the organic and inorganic composition of the residue of embalming material sampled from the skulls to be achieved and also permitted us to exclude the presence of possible products used during past restoration cure.

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.

Background Establishing the distribution of materials in paintings and that of their degradation products by imaging techniques is fundamental to understand the painting technique and can improve our knowledge on the conservation status of the painting. The combined use of chromatographic-mass spectrometric techniques, such as GC/MS or Py/GC/MS, and the chemical mapping of functional groups by imaging SR FTIR in transmission mode on thin sections and SR XRD line scans will be presented as a suitable approach to have a detailed characterisation of the materials in a paint sample, assuring their localisation in the sample build-up. This analytical approach has been used to study samples from Catalan paintings by Josep Maria Sert y Badía (20th century), a muralist achieving international recognition whose canvases adorned international buildings. Results The pigments used by the painter as well as the organic materials used as binders and varnishes could be identified by means of conventional techniques. The distribution of these materials by means of Synchrotron Radiation based techniques allowed to establish the mixtures used by the painter depending on the purpose. Conclusions Results show the suitability of the combined use of SR μFTIR and SR μXRD mapping and conventional techniques to unequivocally identify all the materials present in the sample and their localization in the sample build-up. This kind of approach becomes indispensable to solve the challenge of micro heterogeneous samples. The complementary interpretation of the data obtained with all the different techniques allowed the characterization of both organic and inorganic materials in the samples layer by layer as well as to establish the painting techniques used by Sert in the works-of-art under study.

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.