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The article illustrates the MOLAB research project devoted to the non-invasive investigation of pre-Hispanic and colonial Mesoamerican manuscripts. In the present paper, we provide a description of the project and its aims, listing the artworks so far investigated and describing analytical techniques we employed. A presentation of the data obtained by the scientific analyses is then followed by a description of the main cultural and historical interpretive venues that can be pursued through a strongly interdisciplinary approach such as the one adopted by the MOLAB.

In this review, the main technological processes involved in the production of color in glasses, ceramics and pigments are reported. Iron (as oxides or dispersed ion) is the main responsible of the color in archeological and historical ceramics and glasses, but other d-metals can be also found (Cu, Ag, Co, Cr, Ni) as nano-particles or dispersed ions. The final coloration is usually a result of the sapient choice of raw materials and firing conditions (temperature, atmosphere). Some pigments are chosen to represent the different, often sophisticated, chemical processes that have been used during the history to produce them: solid state reaction (Egyptian and Chinese Blue, Naples Yellow, Ultramarine Blue), host-guest complexation (Maya Blue), corrosion/redox processes (Lead White, Verdigris), wet/solution synthesis (Prussian Blue, Cadmium Yellow). In addition, a brief overview on the vast production of modern compounds (inorganic and mostly organic) is given. This review shows how behind the artistic choice and way of expression lies a high level of technological skill and chemical knowledge achieved/reached by (ancient) craftsmen to obtain the desired colors.

In this study a multi-analytical approach has been performed to characterise the constitutive materials of an ancient painted barkcloth or Tapa. Originating from Wallis Island, Polynesia, this cloth likely served utilitarian or ceremonial purposes and is part of the Felice Junck collection at the Pigorini, Muciv museum of Rome. During a recent conservation project, some micro-samples were taken from the support, brown and black painted areas and were investigated using the complementarity of SEM-EDX, FT-IR, Raman/SERS and solid-state 13C NMR and 1H HR-MAS spectroscopy. The combination of these techniques allowed the chemical characterization of the constitutive materials, from distinguishing the lignin and cellulose content of the support to the use of organic materials including condensed tannins (catechin, anthocyanidins, alkaloids), phlobaphene and vegetal anthraquinone based Morinda genus dyes for the decorations. A primary focus was placed on an understanding of its state of conservation where data of alteration products collected, namely metal carboxylates and oxalates can serve to formulate apt restoration efforts for this specific artefact.

The article, based on the results of non-invasive scientifical analyses, illustrates the changes occurred in the technology of codex painting in early colonial Mesocamerica.

Presentación de los resultados obtenidos a través de análisis científicos no-destructivos realizadas sobre el Códice Vaticano B, un manuscrito Mesoamericano preservado en la Biblioteca Apostolica Vaticana

The fugitive nature of the colorants obtained from sappanwood (Caesalpinia sappan L.) or the South American species commonly known as ‘brazilwoods’ (including other Caesalpinia species and Paubrasilia echinata (Lam.)) makes the identification of brazilwood dyes and pigments in historic artefacts analytically challenging. This difficulty has been somewhat alleviated recently by the recognition and structural elucidation of a relatively stable marker component found in certain brazilwood dyes and pigments—the benzochromenone metabolite urolithin C. This new understanding creates an ideal opportunity to explore the possibilities for urolithin C’s localization and identification in historical artefacts using a variety of analytical approaches. Specifically, in this work, micro-destructive surface-enhanced Raman spectroscopic methods following a one-sample two-step (direct application of the colloid and then subsequent exposure of the same sample to HF before reapplication of the colloid) approach are utilized for the examination of four historical brazilwood dyed textiles with the results confirmed via HPLC-DAD analysis. It is shown that characterization of reference urolithin C is possible, and diagnostic features of this molecule can also be traced in faded historical linen, silk and wool textiles, even in the presence of minor quantities of flavonoid, indigoid and tannin components. The exploitation of the same micro-sample through a series of SERS analyses affords a fuller potential for confirming the characterization of this species.

This chapter provides a description of colour changes in the Amsterdam Sunflowers due to chemical alteration of pigments, with a focus on geranium lakes and chrome yellows. The brilliant and forceful colours of these and other late nineteenth-century synthetic materials offered artists such as Vincent van Gogh new means of artistic expression that exploited a range of contrasting hues and tints. However, geranium lakes have a strong tendency to fade and chrome yellows to darken under the influence of light. Van Gogh, like other artists of his day, was aware of this drawback, yet he continued to favour the use of both pigments up until his death in July 1890 due to the unparalleled effects they gave. In April 1888, Vincent wrote to his brother Theo: Van Gogh's use of unstable colours opens a series of questions regarding the extent to which colour change affects the way his paintings look today, as discussed here in relation to the Amsterdam Sunflowers. Furthermore, given the frequency with which geranium lakes and chrome yellows occur in Van Gogh's paintings of the period 1888–90 and the predominance of chrome yellows in Sunflowers, it becomes important to understand the factors that can drive these processes of deterioration in order to develop appropriate strategies for conserving the artist's works.

In this work the formulation of 20 Johann Faber felt-tip pens commercialized in the 1960s and belonging to and used by the architect and designer Lina Bo Bardi have been investigated by an integrated analytical methodology. Minimally destructive vibrational spectroscopic methods permitted a qualitative interpretation of constituents which could be corroborated and ulteriorly supplemented by more destructive chromatographic techniques. This combined approach constitutes an effective collaboration for an in-depth study chronicling the chemical characterization of the first era of commercially viable felt-tip pen inks by providing for the identification of dyes and separation of their mixtures (triarylmethanes, xanthenes, indigoids, azo dyes, azines), binders (plant gums) and additives (diethylene glycol, phenols/antioxidant, diisoctyl phthalate/plasticizer). The comparison between the early and more recent commercial felt-tip pens has allowed to differentiate dyes, pigments and binders, which may provide a useful reference for future studies on the chemical characterization of historical samples.

Among the artists’ materials of the nineteenth century, pastel crayons merit scientific interest since their early commercial formulations are mostly unknown and, until now, have been considerably less studied with respect to other contemporary painting materials. In this framework, research herein reports the results of a comprehensive multi-analytical study of 44 pastel crayons of two recognized brands (LeFranc and Dr. F. Schoenfeld) from the Munch museum collection of original materials belonging to Edvard Munch. The integrated use of complementary spectroscopic and hyphenated mass-spectrometry techniques allowed the compositional profiles of the crayons to be traced providing the identification of the inorganic and organic pigments, the fillers/extenders and the binders. All crayons resulted to be oil- based and the binder was identified to be a mixture of a drying oil (safflower or linseed oil), palm oil or Japan wax and beeswax. Among others, pigments such as ultramarine, chrome yellows, Prussian blue, manganese violet, viridian and madder lake have been identified. A significant alignment in formulations of the brands was observed with the only exception of the greens which showed distinctive pigment and filler compositions. The analytical information provided for these commercial artists’ materials will be of great interest for academia, museum and other institutions hosting art collections dating from the same period and it will be used by the Munch museum to draw proper conservation strategies of its own artwork collections.

The IPERION HS project aims at establishing and operating an integrated activity for the establishment of a distributed pan-European research infrastructure on heritage science. Since 2016 heritage science is included in the ESFRI Roadmap through E-RIHS, the European Research Infrastructure on Heritage Science, evolving towards becoming an ERIC. Looking forward towards such time, IPERION HS will provide the pan-European heritage science community with a further level of integration and its rules and procedures are aimed at adaptation and improvement for future adoption under E-RIHS ERIC. As results from the working of a previous project of organizational nature (E-RIHS PP) the quality of a partner to the future ERIC will be established through an evaluation combining: i) a confirmation of the capacity to do things well; and ii) an assurance that such capacity is suitably managed to bear fruit in terms of results. For that purpose, the outcomes of actions taken by a partner will be evaluated as pertains e.g. their impact and the satisfaction of users. Known partners, those that have already co-operated within the group and are therefore recognized by their activities and the respective results, will be subjected to a simplified evaluation, namely attending to existing feedback from previous users, while new partners will be subjected to a complete evaluation. One of the main aims of quality monitoring under IPERION HS is to establish a background of data allowing to consider the partners of this project for a simplified evaluation scheme if, in the future, they apply to become partners to E-RIHS ERIC. A basic quality and evaluation system for the services rendered through the project and for its other outcomes is set by this task, based on flexibility and self-evaluation. The task also sets a group of Key Performance Indicators (KPIs) from which should evolve those to be used after the ERIC is established. KPIs will be aimed at forming a reliable picture of the evolution of the project in terms of conformity with set goals, progression of important factors and satisfaction of users in the broad sense of the word. Finally, the task will set ethical principles by which all those working within the Project and, later, under the E-RIHS brand are bound to abide. Those principles are expected to be consequent through procedures followed in all operations. The deliverable was developed from work done under E-RIHS PP and from the results of an ESFRI Working Group on the monitoring of research infrastructures performance published in December 2019. It includes contributions of IPERION HS WP 2, WP 3 and WP 4 on the survey of users' satisfaction and of WP 8 on the dissemination and communication KPIs.

As part of an ongoing interdisciplinary project, aimed at disclosing pre-Hispanic Mesoamerican codex painting technologies, a set of non-invasive analyses has been carried out by the MOLAB European mobile facility on the two pre-Hispanic codices today held by the Biblioteca Apostolica Vaticana, commonly known among Mesoamericanists as Codex Borgia (Borg. mess. 1) and Codex Vaticanus B (Vat. lat. 3773).

During solvent cleaning of a painted surface, the control of solvent diffusion into the painting matrix is a primary concern for conservators. In this work, a comparative systematic study of solvent ingress and of the ensuing swelling phenomenon in paint films due to cleaning treatments was tackled using single-sided NMR. Specifically, the effects of a TAC aqueous solution (triammonium citrate in deionized water) applied in both free and gelled forms (by Klucel (R) G) on acrylic emulsion and vinyl-based model paints were evaluated. Notably, the NMR measurements (proton spin density depth profiles and transverse relaxation decays) collected before, during, and after these wet-cleaning tests proved that the use of the aqueous gel did not significantly minimize the penetration and the swelling action of water compared with the free solution. Furthermore, swelling effects associated with the use of an organic solvent (ligroin) were evaluated by NMR profilometry on varnished oil and egg-tempera paints. In this case, by comparing the depth profiles collected before and after the solvent treatments, a moderate paint swelling was observed followed by a width reduction of the paint films ascribable to the removed varnish layer. Overall, the reported NMR results reveal the analytical potentialities of the technique for a non-invasive assessment of the swelling effect of paint films subjected to cleaning (by water or an organic solvent), thereby providing an analytical method in support to the conservators' practice.

We present the results of a diagnostic campaign on three of Giuseppe Capogrossi&rsquo, s abstract paintings from the 1950s and 1960s, conserved at the National Gallery of Modern and Contemporary Art in Rome. Non-invasive investigations by reflection FT-IR spectroscopy were carried out, followed by micro-destructive laboratory analyses using Py-GC-MS, and HPLC-ESI-Q-ToF. The investigations focused on identifying the binders used for both the preparation and the pictorial layers. In two of the paintings investigated, an industrial preparation was identified based on egg yolk, mixed with other organic materials (acryl resin, oil, animal glue). The paint media include the use of both oil and alkyd paint. In one of the three paintings, the presence of a styrene-acryl resin was observed. The results show the simultaneous use of traditional and innovative materials, confirming the complexity of the period in which the artist was active, characterized by the technical experimentation of both the artists and manufacturers. The research also contributes to a better understanding of Giuseppe Capogrossi&rsquo, s artistic profile, from the point of view of executive techniques.

Vincent van Gogh used fugitive red lake pigments that have faded in some paintings. Mapping their distribution is key to understanding how his paintings have changed with time. While red lake pigments can be identified from microsamples, in situ identification and mapping remain challenging. This paper explores the ability of molecular fluorescence imaging spectroscopy to identify and, more importantly, map residual non-degraded red lakes. The high sensitivity of this method enabled identification of the emission spectra of eosin (tetrabromine fluorescein) lake mixed with lead or zinc white at lower concentrations than elemental X-ray fluorescence (XRF) spectroscopy used on account of bromine. The molecular fluorescence mapping of residual eosin and two carmine red lakes in van Gogh's The Olive Orchard is demonstrated and compared with XRF imaging spectroscopy. The red lakes are consistent with the composition of paint tubes known to have been used by van Gogh.

The identification of natural dyes in ancient textiles is a longstanding challenge for scientists; yet, the effort honours the skill and knowledge of master dyers by retracing traditional dyeing methods and assisting in conserving historical treasures for future generations. Here, the main constituents of selected native Japanese extracts from the roots of Lithospermum erythrorhizon and Scutellaria baicalensis, the barks of Phellodendron amurense and Morella rubra, the dried flower bud of Syzygium aromataticum, and the fruit of Terminalia chebula are determined by surface-enhanced Raman spectroscopy following traditional Japanese extraction methods. The analytical amalgamation of data from SERS examinations on crude extracts and on subsequently refiltered and diluted extracts provides further effective and sensitive results for the combined identification of napthoquinones (shikonin and alkanin), alkaloid (berberine), polyhydroxyflavonoids (baicalin/baicalein, myricetin/myricitrin), diarylheptanoids, allylbenzene (eugenol), and tannins (gallic/ellagic acid). The comparison of results from this analytical protocol with those achieved by the more traditional chromatographic and mass spectrometric method provides and questions data regarding generally accepted marker components and enantioselective discriminations that serve to enrich the database of biological sources of colouring materials to be used in determining historically important Japanese colorants and dyestuffs.

Synchrotron radiation (SR)-based X-ray methods are powerful analytical tools for several purposes and we widely use them for probing the degradation mechanisms of inorganic artists’ pigments in paintings, including chrome yellows (PbCr1-xSxO4; 0 ≤x≤0.8), a class of compounds often found in Van Gogh masterpieces. However, the high intensity and brightness of SR beams raise important issues regarding potential damages of the analyzed samples. A thorough knowledge of the SR X-ray sensitivity of each class of pigment in the painting matrix is therefore required to find analytical strategies that contribute to minimize the damage for preserving the integrity of the analyzed sample and to avoid misinterpretation of the data. Here, we employ a combination of Cr K-edge X-ray absorption near edge structure (XANES) spectroscopy, Cr-Kβ X-ray emission spectroscopy (XES) and X-ray diffraction (XRD) to monitor and quantify the effects of SR X-rays on the stability of chrome yellows and related Cr-compounds and to define strategies for mitigating their damage. We found that the SR X-ray beam exposure induces changes in the oxidation state and local coordination environment of Cr-ions and leads to a loss of the compound’s crystalline structure. The extent of X-ray damage depends on some intrinsic properties of the samples (chemical composition of the pigment as well as the presence/absence and nature of the binder) and it can be minimized by optimizing the overall fluence/dose released to the samples and by working in vacuum and cryogenic conditions.

The performance of non-invasive chemical analyses on various pre-Hispanic Mesoamerican codices to chemically characterize their painting materials has recently opened new avenues into research on the ancient Mesoamerican book painting tradition. In this chapter, a comparative effort is undertaken in order to shed light on the technological relationships linking codices pertaining to different scribal traditions. Scientific results are also contrasted with historical data contained in Colonial textual sources, providing information on the paints used by ancient Mesoamerican painters and scribes.

The aim of the present chapter is to evaluate the introduction of oil-modified alkyd resins in the painting practice of Jackson Pollock. Using a non-invasive approach based on FT-IR reflection spectroscopy measurements, eleven works by the artist dated from 1942 to 1947 have been examined at the Peggy Guggenheim Collection (PGC, Solomon R. Guggenheim Foundation) in Venice. The selected years represent a seminal period of experimentation for Pollock, which marked his evolution from a more figurative subject matter to full abstract painting, achieved with his unconventional dripping technique. The study of eleven works from the PGC has been integrated with previous data on other additional fourteen paintings representing Pollock's artistic production from 1943 to 1952. The results confirm that dripping paints appeared before the use of alkyds, Pollock in fact started experimenting with his new technique using both artists' and house paints. Oil-modified alkyds were introduced for the first time in two paintings of 1946, although offered Pollock the suitable binder for expansively expressing his action painting in works after 1947.

The electronic and vibrational properties of red lead pigment, the mixed valence lead oxide compound Pb3O4, known as minium, have been studied by means of first principle calculations based on Density Functional Theory (DFT) and Fourier Transform–Infra Red (FT-IR) and Raman spectroscopies. The aim of the present investigation is to validate an integrated theoretical-experimental approach for modelling the structural, electronic and spectroscopic properties of minium and to define its structure-properties relationships. The calculated band gap performed using GW approximation is in excellent agreement with the experimental one and improves previous results found in literature. The simulated vibrational IR and Raman spectra are able to reproduce the main features of the experimental spectra and to assign the normal modes related to the experimental bands. The combined theoretical and experimental study of the electronic and vibrational properties of Pb3O4 allows to clarify the mechanism of lead whitening as well as to interpret ambiguous Raman spectra of minium in terms of resonance effects.

International audience; In Heritage Science, the evaluation of stone consolidation treatments by investigating the nature of in situ newly formed products and their penetration depth within the consolidated matrix is a grand challenge. A number of analytical methods have been proposed, but, currently, most of them are not able to supply a full overview of the spatial, structural and compositional information of the newly formed crystalline and amorphous phases with a submicrometric lateral resolution. Here, we examined, the capabilities of synchrotron radiation (SR)-based two-dimensional X-ray absorption near-edge structure (2D-XANES) spectroscopy at Ca K-edge for determining the structural and compositional properties of the compounds formed after the application of a calcium acetoacetate-based consolidant on a porous carbonatic stone (limestone) and for investigating their stratigraphic distribution at the submicrometric scale length. We evaluated advantages and drawbacks of three Ca K-edge 2D-XANES-based approaches: (i) transmission mode full-field-XANES (FF-XANES) imaging; (ii) micro-X-ray fluorescence (μ-XRF) mapping above the Ca K-edge combined with the acquisition of XRF mode μ-XANES spectra at a limited number of spots; (iii) full-spectral µ-XANES (FS µ-XANES) mapping in XRF mode and its variant called selectively induced X-ray emission spectroscopy (SIXES) mapping. Overall, Ca K-edge 2D-XANES spectroscopy provided accurate qualitative and semi-quantitative information on the newly formed calcium carbonates (i.e., amorphous calcium carbonate, vaterite and calcite) and their stratigraphic distribution at the submicrometric scale, thus opening a new scenario to study the carbonatation process of calcium-based consolidants in limestones. Stone consolidation is a major challenge for protection of buildings and stone artefacts from weathering and decay, which usually lead to decohesion of the structural elements of the material. Over the last decades, thanks to the progress in material science and nanotechnology, a wide range of novel materials has been developed, with the aim of re-establishing adhesion, cohesion and stability of the damaged stone as well as to improve efficacy and durability of the treatment 1,2. The effectiveness of a consolidation treatment depends on different aspects, including penetration depth, reaction kinetics and mechanism of formation of the final products, and physical chemical properties of the consolidant phase in the stone matrix. In consideration of that, tailored analytical tools and methodologies have been developed to characterize newly synthesized consolidation products and to understand the chemistry behind their performances. Although open

MOLAB is a unique collection of integrated mobile instrumentation established in Italy in 2001 and open from 2004 to transnational access within the European projects Eu-ARTECH (FP6) and CHARISMA (FP7). Its application demonstrated in the last decade that satisfactory analytical results can be obtained through in situ studies of a variety of heritage objects without sampling or moving them to a laboratory, achieving significant overviews on nature and behavior of the inorganic and organic materials of the examined object. The MOLAB in situ non-invasive approach produced a significant change in diagnostic practices, an increase of scientific inputs in heritage studies and conservation, and a positive modification in the relationships between curators, conservators, and scientists, permitting a common language to be established and partnership strengthened. The recent introduction of innovative mobile 2D and 3D imaging systems, setup within the CHARISMA joint research project, significantly extended the MOLAB tools available in the current project IPERION CH (Horizon 2020), widening number and interest of potential users from Europe and associated countries. MOLAB est un ensemble unique d’instruments mobiles intégrés créé en Italie en 2001 et disponible à un accès transnational depuis 2004 dans le cadre des programmes européens Eu-ARTECH (6e PC) et CHARISMA (7e PC). Son utilisation a démontré au cours des dix dernières années que l’on peut obtenir des résultats analytiques de qualité par des travaux in situ sur différents types d’objets du patrimoine sans avoir à prélever des échantillons ou à les transporter dans un laboratoire, et recueillir des informations importantes sur la nature et le comportement des matériaux organiques et inorganiques de l’objet examiné. Les méthodes in situ et non invasives du MOLAB ont favorisé une inflexion notable des pratiques diagnostiques, une augmentation de la production scientifique dans les sciences du patrimoine et la conservation-restauration, ainsi qu’une évolution positive des relations entre conservateurs de musées, restaurateurs et chercheurs, contribuant à l’adoption d’un langage commun et au renforcement des collaborations. L’introduction récente de systèmes mobiles d’imagerie en 2D et en 3D, mis au point grâce aux activités conjointes de recherche de CHARISMA, a considérablement élargi la gamme des outils du MOLAB disponibles dans le cadre du projet en cours IPERION CH (horizon 2020), accroissant ici le nombre et les motivations des utilisateurs potentiels en Europe et dans les pays associés.

Cadmium yellows (CdYs) refer to a family of cadmium sulfide pigments, which have been widely used by artists since the late 19th century. Despite being considered stable, they are suffering from discoloration in iconic paintings, such as Joy of Life by Matisse, Flowers in a blue vase by Van Gogh, and The Scream by Munch, most likely due to the formation of CdSO4 ⋅n H2 O. The driving factors of the CdYs degradation and how these affect the overall process are still unknown. Here, we study a series of oil mock-up paints made of CdYs of different stoichiometry (CdS/Cd0.76 Zn0.24 S) and crystalline structure (hexagonal/cubic) before and after aging at variable relative humidity under exposure to light and in darkness. Synchrotron radiation-based X-ray methods combined with UV-Vis and FTIR spectroscopy show that: 1) Cd0.76 Zn0.24 S is more susceptible to photooxidation than CdS; both compounds can act as photocatalysts for the oil oxidation. 2) The photooxidation of CdS/Cd0.76 Zn0.24 S to CdSO4 ⋅n H2 O is triggered by moisture. 3) The nature of alteration products depends on the aging conditions and the Cd/Zn stoichiometry. Based on our findings, we propose a scheme for the mechanism of the photocorrosion process and the photocatalytic activity of CdY pigments in the oil binder. Overall, our results form a reliable basis for understanding the degradation of CdS-based paints in artworks and contribute towards developing better ways of preserving them for future generations.