La Química de l'art

Els materials que formen part d'una obra d'art, per les seves característiques de disponibilitat, disposició i concentració requereixen per a la seva anàlisi unes metodologies de mostreig i de preparació adaptades, així com la utilització de tècniques microanalítiques. Dels resultats es pot obtenir informació molt diversa i útil per al millor coneixement i conservació de les obres. Es mostren alguns exemples on les eines químiques aplicades al coneixement de l'art permeten conèixer les tecnologies de producció i origen dels materials, relacionar-los amb manuscrits i receptes antigues, interpretar fenòmens d'alteració, estudiar la reactivitat i els productes de reacció així com determinar cronologies.Els materials que formen part d?una obra d?art, per les seves característiques de disponibilitat, disposició i concentració requereixen per a la seva anàlisi unes metodologies de mostreig i de preparació adaptades, així com la utilització de tècniques microanalítiques. Dels resultats es pot obtenir informació molt diversa i útil per al millor coneixement i conservació de les obres. Es mostren alguns exemples on les eines químiques aplicades al coneixement de l?art permeten conèixer les tecnologies de producció i origen dels materials, relacionar-los amb manuscrits i receptes antigues, interpretar fenòmens d?alteració, estudiar la reactivitat i els productes de reacció així com determinar cronologies. The chemical analysis of materials in works of art requires special techniques both in the sampling process as well in the preparation of probes. In this field, the use of microanalytical techniques is essential. Interestingly, a great wealth of information can be obtained from chemical analysis, that provides a better knowledge of the artwork as well as on the conservation techniques. In this article we review some examples where the application of chemical characterization techniques applied to works of art have been important in obtaining a precise knowledge on the production techniques of the materials as well as on their origin, relating them to manuscripts describing old recipes. These techniques allow us also to interpret the phenomena that change a work of art along the time, to study the chemical reactivity of the materials and their reaction products, a knowledge that can be used to establish a chronology of the artwork

Ageing of resin from Pinus species assessed by infrared spectroscopy

Resins obtained from Pinus genus species have been widely used in very different fields throughout history. As soon as the resins are secreted, molecular changes start altering their chemical, mechanical and optical properties. The ageing processes are complex, and the chemical and structural changes associated with resin degradation are not yet fully known. Many questions still remain open, for instance changes happening in pimaranes, one of the two diterpenoid constituents of the resin. A systematic study of the ageing process of Pinus resins is done through Fourier transform infrared spectroscopy (FTIR) using chemical standards and complementing the obtained results with gas chromatography coupled to mass spectrometry (GC/MS) analysis when necessary. Moreover, long-term degradation processes are also investigated through the analysis of a selection of dated historical resins. This study overcomes the limitations of GC/MS and brings new information about the reactions and interactions between molecules during Pinus resin ageing processes. It also provides information about which bonds are affected and unaffected, and these can be used as specific markers of the degradation and of the resins themselves. [Figure not available: see fulltext.]Peer ReviewedPostprint (author's final draft

Micro infrared spectroscopy discrimination capability of compounds in complex matrices of thin layers in real sample coatings from artworks

The presence of coating on manufactures either to protect them from the environment, or to give them specific properties—as well as simply to change their aspect—has been shown to be a constant practise throughout history. Their characterization is complex not only because of the inherent variability and diversity of the composition, but also due to the small amount of sample material available. A methodology to study those coatings using microFTIR is proposed. In some cases, the use of microSR-FTIR, which heavily increases spatial resolution particularly appropriate for the analysis of these heterogeneous samples, is also proposed. Data processing tools such as distribution maps of specific infrared bands and curve fitting facilitate the interpretation of the spectra and help identify heavily overlapped spectra. Through the identification of individual bands, it has been possible to discriminate materials and comprehend the interaction processes during aging. Infrared spectra from reference aged materials of known production dates and which are essential in understanding those processes are given. A set of selected case studies including materials of different chemical natures and various historical periods are presented: identification of guanine on the inner coating of a hope chest; determination of a protein glue coating from a gilded Baroque altarpiece; assessment of a beeswax superficial application during the historical restoration of a late 19th century canvas painting; identification of impurities of shellac wax in a shellac coating on a wood moulding from a medieval altarpiece; aging and reaction compounds in Pinus resin, drying oil and green copper pigment mixtures used as colour coatings on Baroque and modern desks.Peer ReviewedPreprin

The role of microspectroscopy techniques in the study of historic artworks

Peer ReviewedPostprint (published version

The “Historical Materials BAG”: A new facilitated access to synchrotron X-ray diffraction analyses for cultural heritage materials at the European Synchrotron Radiation Facility

(This article belongs to the Special Issue Advances in Analytical Strategies to Study Cultural Heritage Samples)The European Synchrotron Radiation Facility (ESRF) has recently commissioned the new Extremely Brilliant Source (EBS). The gain in brightness as well as the continuous development of beamline instruments boosts the beamline performances, in particular in terms of accelerated data acquisition. This has motivated the development of new access modes as an alternative to standard proposals for access to beamtime, in particular via the “block allocation group” (BAG) mode. Here, we present the recently implemented “historical materials BAG”: a community proposal giving to 10 European institutes the opportunity for guaranteed beamtime at two X-ray powder diffraction (XRPD) beamlines—ID13, for 2D high lateral resolution XRPD mapping, and ID22 for high angular resolution XRPD bulk analyses—with a particular focus on applications to cultural heritage. The capabilities offered by these instruments, the specific hardware and software developments to facilitate and speed-up data acquisition and data processing are detailed, and the first results from this new access are illustrated with recent applications to pigments, paintings, ceramics and wood.The Historical materials BAG has been implemented with support from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870313, Streamline, which also supports APC. L. H. is funded via the PANOSC project (European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No. 823852). I. F. is funded by a grant from the Marie Skłodowska-Curie COFUND Programme “InnovaXN” (contract number 847439 with the European Commission). The ESRF beamtime was granted through the peer-review BAG proposal HG-172 at ID13 and ID22 and in-house beamtime at ID21. The project on wood vessels received financial support from MINECO (Spain), Ref. PID2019-105823RB-I00. The project on cadmium red pigments was financially supported from the Horizon 2020 project IPERION-HS (H2020-INFRAIA-2019-1, GA No. 871034) and the Italian project AMIS (Dipartimenti di Eccellenza 2018–2022, funded by MIUR and Perugia University). V.G. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 945298-ParisRegionFP. E.A.C. and K.J. would like to acknowledge the project Smart*Light funded by the Interreg V Flanders-Netherlands program with financial support from the European Regional Development Fund (ERDF) for funding in assessing the damage caused by X-rays to model paints. K.J. acknowledges FWO (Brussels) for financial support through grants G054719N and I001919N. F.V. and K.J. acknowledge BELSPO (Brussels) for funding of the FEDtWIN mandate Macro-Imaging. C.C. (Christelle Chauffeton) is grateful to the Fondation Bettencourt-Schueller and the Cité de la Céramique Sèvres-Limoges, France for founding her work in the frame of her PhD thesis. A part of this study has been funded by the Grant-in-Aid for Scientific Research [18700680], JSPS Grant-in-Aid for Young Scientists (B) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.Peer ReviewedArticle signat per 28 autors/es: Marine Cotte, Victor Gonzalez, Frederik Vanmeert, Letizia Monico, Catherine Dejoie, Manfred Burghammer, Loïc Huder, Wout de Nolf, Stuart Fisher, Ida Fazlic, Christelle Chauffeton, Gilles Wallez, Núria Jiménez, Francesc Albert-Tortosa, Nati Salvadó, Elena Possenti, Chiara Colombo, Marta Ghirardello, Daniela Comelli, Ermanno Avranovich Clerici, Riccardo Vivani, Aldo Romani, Claudio Costantino, Koen Janssens, Yoko Taniguchi, Joanne McCarthy, Harald Reichert and Jean Susini.Postprint (published version

Teräsrakenteisen pressuhallin rakenteen varmistaminen

Opinnäytetyön tavoitteena on tuottaa tilaajalle viranomaisten vaatimat lupakuvat ja laskelmat vaurioituneen pressuhallin uudelleen pystytystä varten. Suunnittelutyöhön kuului kuormien kantavuuden tarkastelu Autodesk Robot Structural Professional 2014 -ohjelmalla ja rakenteen kestävyyden parantaminen. Lopuksi esitetään perustusratkaisuksi ankkurointiperustusta ja tarkastellaan teräsrakenteen liitosten kestävyyttä. Opinnäytetyöhön ei kuulu LVIS-suunnitelmia.The purpose of the thesis was to get new images for the authorities of a damaged canvas hall to rebuild the hall for storage use. In the thesis the required calculations were also made. The planning work included a load bearing analysis with Autodesk Robot Structural Professional 2014 –program and improving structure resistance. In the end anchoring was suggested as a foundation as well as the joint durability of the steel structures was reviewed. The thesis does not include HVAC-plans

Interacció entre les roques i l'atmosfera: desenvolupament i evolució de pàtines a la conca mediterrània.

[cat] Les superfícies de les roques exposades en condicions subaèries interaccionen amb l'entorn mediambiental i canvien algunes de les seves característiques, principalment el color, la textura, la composició, etc., de tal manera que la formació d'una pàtina és resultat de diversos mecanismes. A la conca mediterrània, la majoria dels afloraments naturals i superfícies de monuments mostren un color taronja comú, l'anàlisi del qual mostra que és un dipòsit mineral de calcita com a component principal. En el present article, es caracteritzen aquests dipòsits des d'un punt de vista mineralògic, químic i físic (propietats òptiques) i es discuteix una hipòtesi de la seva formació per comparació entre algunes pàtines aparegudes en afloraments naturals i les observades en els monuments. També es discuteix el seu possible origen biològic o basat en l'acció de l'home.[eng] The surfaces of the rock exposed in subaerial conditions interact with the environment, changing some of their characteristics, namely colour, surface features, composition, etc., and thus, a patina is formed as a consequence of several mechanisms. In the Mediterranean basin, most of the natural outcrops and monumental surfaces exhibit a common orange colour, the analyses of which demonstrated that it is mainly a laminar deposit of calcite. In this paper, these deposits are characterised from the mineralogical, chemical and physical (optical properties) points of view, and a hypothesis of their formation, development and evolution (decay) is discussed on the basis of the comparison between some naturally occurring patinas and those of the monuments. Their possible biological or man-made origin is also discussed

The three-tone system in Sant Climent de Taüll wall paintings: an imprint of medieval treatises

Medieval texts describe the use of the three-tone system as a pictorial procedure characteristic of Romanesque art to represent shape and volume. Some Medieval art treatises provide detailed instructions of its application, using specific names for each of the carnation colours: membrana (mid-tone or base colour), rosa and posc (darker) and lumen (lighter). In this study we have verified its use and application by analysing the mural paintings of the central apse of the church of Sant Climent de Taüll (Catalonia), currently on display at the Museu Nacional d'Art de Catalunya. A combination of microanalytical techniques, micro-infrared spectroscopy (µFTIR), synchrotron-based micro-X-ray diffraction (µSR-XRD), Scanning Electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and Optical microscopy (OM), provided precise information on the composition and distribution of the compounds in the sequence of micrometric layers. We have identified the use of up to eight different pigments carefully mixed, to obtain a variety of tones in accordance to the recipes given in the Theophilus’ De diversis Artibus and the Hermeneia (Byzantine pictorial tradition). The inner layers, painted directly on the still wet lime mortar, show the typical carbonation microstructure of fresco, while the surface layers for the contours of geometric decorative elements and figures which required longer working times, were applied al secco.This work was financially supported by MINECO (Spain, PID2019–105823RB-I00) and Generalitat de Catalunya (2021 SGR 00343). µSR-XRD experiments were performed at BL13-XALOC beamline at ALBA Synchrotron in collaboration with its staff. We thank Museu Nacional d'Art de Catalunya MNAC and the cooperation of conservators and curators, especially Mireia Mestre and Paz Marquès.Peer ReviewedPostprint (published version

SR-XRD and SR-FTIR study of the alteration of silver foils in medieval paintings

Altarpieces and polychrome carved wood from the fifteenth century AD usually exhibit golden and silvery areas by the application of a very thin foil of metal. The metal foils were normally protected from the atmosphere by a varnish or resin which maybe either preserved or absent. Moreover, they were glued to the background surface by adhesive substances (egg yolk, drying oil or animal glue). The high proportion of the glueing substances often renders the development of reaction compounds. With time, silver alters blacken or simply disappear completely. In this paper, we study the alterations to metal foils from a selection of fifteenth century artworks showing different glueing agents, organic coatings and several degrees of conservation of the organic coatings and metal leafs. The submillimetric layered structure and the high variability and low amount of most of the compounds present in the different layers, as well as their differing nature (organic and inorganic) make the use of micron-sensitive highresolution techniques essential for their study. In particular, the high resolution, high brilliance and small footprint renders synchrotron radiation most adequate for their study. SR-XRD was performed to identify the reaction compounds formed in the different layers; μFTIR was used at to identify the silver protecting organic coatings, the metal foil glueing layers and the corresponding reaction compounds. The results obtained suggest that atmospheric corrosion is the dominant mechanism, and therefore that the degree of corrosion of the metal foils is mainly related to the conservation state of the protecting coatings.Peer ReviewedPostprint (published version