Gilding for Matter Decoration and Sublimation. A Brief History of the Artisanal Technical Know-how

IJCS it is an open access journal. All content is freely available without charge to any user or his/her institutionInternational audienceThe process used to decorate art objects with thinner and thinner gold coatings varied during centuries. Foil or leaf metal gilding technology was complemented around the beginning of the Christian era by mercury gilding. Simultaneously was developed in some geographic areas the surface depletion process for gilded copper/silver alloys. This paper is motivated by the recent publication by the authors of a didactic opus devoted to the description and the discussion of the technical history of the various gilding procedures, based on the study by modern investigation techniques of a number of gilded museum objects. Through examples from laboratory studies on museum objects, the main evolution steps of gold application are described. A recent mechanical modelling work about gold leaf forming by beating is reported. The different coating processes are discussed, depending on the substrate nature and surface treatment before gilding. It includes high temperature firing for mercury gilding, or powder gilding, e.g. on Middle-Age Syria glass. The paper ends with a listing of the research perspectives open for the presently poorly developed study of the adhesion mechanisms between gold leaf and its substrate. It discusses the important issue of gold-metal interdiffusion during metal gilding processes involving a high temperature step

Materials Surface Science Applied to the Investigation of Cultural Heritage Artefacts

This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/International audienceThe skill of ancient artisans manufacturing artistic or everyday artworks surprises the modern material scientists. We show, through the study of archaeological pieces, how laboratory research instruments use enlightens the fabrication processes of unique items at antic periods. The specificity of surface science research favouring non-invasive means for investigations on museum objects is emphasised. The examples concern: Nanostructured layers on ceramic surface to obtain the so-called lustre effect, invented by ancient Islam potters; Intentional coloration of metallic objects by chemical patination, attested in Egypt on 2nd millenary BC and still applied by Japanese artisans; The history of gilding objects: leaf gilding, mercury gilding, and other processes; The Fresco technique, a perennial wall painting, known by ancient Roman and propagated through centuries. The examples open new fields belonging to the modern materials science, to understand the mechanism involved in processes with the constraint that one does not know all the fabrication steps

Etudes sur le mobilier Boulle, l'ébéniste de Louis XIV : quelques problèmes d'interfaces

National audienceDans le cadre d'un programme mis en place par le musée du Louvre, département des objets d'art, et le C2RMF, autour de l'étude et de la restauration des mobiliers attribués à l'atelier d'André-Charles Boulle ou à ses successeurs, il a été dégagé plusieurs problèmes concernant les marqueteries métalliques et les ornements en bronze doré. Cette communication traite en premier lieu de la compréhension de la mauvaise tenue au vieillissement des collages des pièces de marqueterie en laitons en contradiction avec la bonne tenue des pièces en étain voisines. Les propriétés mécaniques des assemblages laiton/colle/bois et étain/colle/bois utilisant la colle animale, notamment de poisson, ont été étudiées et la rupture prématurée de ces assemblages a pu être expliquée en tenant compte de la rhéologie des composants. En second lieu sont étudiées les dorures des ornements en bronze doré, grâce à l'utilisation des analyses par faisceaux d'ions. Les premiers résultats donnent une idée du procédé de dorure à l'amalgame de mercure utilisé et des épaisseurs d'or appliquées, ainsi que du procédé électrolytique utilisé pour les pièces restaurées

Les bronzes noirs antiques – nouvelles observations et mécanismes de création

Les bronzes noirs sont connus depuis le Moyen Empire égyptien ; leur existence est ensuite attestée à Mycènes, en Grèce et dans la Rome antique, puis au Japon à l’époque moderne. Il s’agit d’une technique de patinage volontaire des alliages du cuivre par des procédés chimiques dont seules les recettes japonaises sont connues. Après une courte introduction historique et quelques considérations sur la structure et la composition des patines de bronzes noirs, cet article fait état d’observations et de reconstitutions de laboratoire inédites. Il s’attache à proposer des interprétations électrochimique et physique sur les mécanismes de formation et les propriétés optiques des couches de patine noire caractéristiques des objets obtenus par ces procédés.Black bronzes have been known to exist since the Middle Kingdom of Egypt: proof of their presence has been found in Mycenae, in Greece and in Ancient Rome, and, in the modern period, in Japan. The black surface was deliberately produced through a patination technique in which copper alloys were chemically treated. Only the Japanese formulas are known today. After a brief historical introduction and a few thoughts on the structure and composition of the black bronze patinas, the paper presents hitherto-unpublished observations and laboratory reconstructions. It seeks to propose physical and electrochemical interpretations of how the black patina was formed and the optical properties of the layered surfaces characteristic of the objects obtained through these processes

New Leaf Gilding Alloys: Physico-Chemistry, Colour, Mechanical Behavior

International audienceIn the frame of a systematic investigation on leaf gilding history and processes, in a research program intending to propose gold leaf alloys specially devoted to restoration, new gold alloys containing low concentration additions of In or Pd were designed and leaves were elaborated in collaboration with the goldbeater Dauvet. The influence of those elements on the colour change induced by alloying was obtained by colorimetry. The microstructural and metallurgical properties of the alloys were studied by scanning electron microscopy (SEM). The foils and leaves were characterized at the different manufacturing steps by EBSD (Backscattered Electron Diffraction), in order to evaluate the effect of the fabrication process on the microstructure and crystallographic texture. Surface segregation of the alloying element, influencing surface colour, was sometimes evidenced and discussed. The mechanical properties of the foils or leaves were measured by micro-and nano-indentation. The obtained properties and behaviour of the new alloys were compared with those of the leaves currently used for leaf gilding. The results conducted the beating company to consider developing new gold leaves production range(s) devoted specially for restoration application. As a result of the present investigation, new manufacturing and gilding procedures have been proposed

La Victoire d’Arles : une dorure à la feuille exemplaire et complexe

Le présent texte résume les résultats de la partie de l’étude de l’applique de la Victoire d’Arles consacrée à la dorure à la feuille qui la décore dans son ensemble. Cette étude vient en complément des premiers travaux exposés dans l’article du catalogue César : le Rhône pour mémoire, 2 ans de fouille dans le fleuve à Arles consacré à l’étude technique de la Victoire, en particulier des analyses faites au CICRP de Marseille en 2009 par Nicolas Bouillon. La dorure a fait au C2RMF l’objet de séries d’examens et de mesures par microscopie optique, fluorescence X portable et analyses PIXE et RBS à l’accélérateur de particules AGLAE. Deux fragments ont été examinés et analysés en microscopie optique à 2 et 3 dimensions, en diffraction de rayons X et au microscope à balayage analytique. Un microprélèvement a également été analysé en chromatographie en phase gazeuse couplée à la spectrométrie de masse. Les résultats permettent de mesurer les épaisseurs des feuilles d’or, de mettre en évidence les recouvrements dus à des redorures et de caractériser la famille chimique de l’adhésif antique employé. Une discussion est engagée concernant la nature des bandes horizontales de dorure bien préservée sur le chiton du personnage.The present article summarises the results of the investigation on the gilding, which covers the Victory of Arles. This study complements the earlier investigation conducted by Nicolas Bouillon at Marseille’s CICRP in 2009 and published in Long, Picard 2009. In the C2RMF laboratory, the gilding was submitted to a series of tests and measurements by optical microscopy, portable X-ray fluorescence and PIXE and RBS analyses on the AGLAE particle accelerator. Two fragments were observed and analysed by two-dimensional and three-dimensional optical microscopy, X-ray diffraction, analytical scanning electron microscopy and by gas chromatography coupled with mass spectrometry of a micro-sample. The results reveal the thickness of the gold leaf, show evidence for areas with gold overlapping due to re-gilding and allow also the characterization of the chemical class of the adhesive used in antiquity for the gold leaf application. A discussion is developed about the nature of the well-preserved gilded bands on the figure’s chiton

Restauration d’un bronze antique : un travail d’Hercule

Le texte résume les travaux de restauration d’une sculpture romaine en bronze représentant Hercule, effectués au Centre de Recherche et de Restauration des Musées de France, ainsi que le travail d’étude mené en amont et en parallèle, tant sur le plan des examens que des analyses. Il s’attache particulièrement à présenter les acquis des différentes techniques utilisées et leur importance pour la détermination des choix de traitements à mettre en œuvre. En effet, cette œuvre récemment découverte n’avait fait l’objet d’aucune restauration. Il a donc été possible de mener une étude complète, et d’orienter les traitements en fonction des résultats.The article summarises the restoration operations conducted at the C2RMF on a Roman bronze sculpture of Hercules, and the different investigations conducted before and during the restoration work, including observations and analyses. It emphasizes in particular the achievements of the various investigative techniques and their importance for determining the choice of technique to employ. The sculpture was recently discovered and had never been submitted to any restoration. It has been thus possible to execute a complete study and to direct the treatments geared towards the results

Ceramics with metallic lustre decoration. A detailed knowledge of Islamic productions from 9th century until Renaissance

Cette publication a fait l'objet d'un article publié en 2012 dans la revue "Matériaux and Techniques" 100, 1 Pages 47-68, disponible sur : http://hal-ensmp.archives-ouvertes.fr/hal-00686405This paper describes research on the technological evolution of glazed ceramics with a metallic lustre decoration starting from their emergence in the Near East until the Hispano-Moresque productions. That research covers the main known Islamic production sites and periods: Abbasid (Mesopotamia); Fatimid (Egypt); Timurid, Mongol, and Safavid (Iran); Ayyubid and Mamluk (Syria); Nasrid and Hispano-Moresque (Spain). It was allowed by the access to more than hundred full preserved objects or fragments supplied by French national museums (Musée du Louvre DAI, Musée national du Moyen Age, Musée national de Céramique). The characterisation of the composition and structure of the ceramics and of their decoration is mostly done through non-destructive analyses methods. The thickness and metal content of the surface lustre layers are quantified thanks to ion beam analyses performed on a particle accelerator: PIXE (particle-induced X-ray emission) for the terracotta and glazes composition and RBS (Rutherford backscattering spectrometry) for the thickness and metal content of the lustre surface layers. The preliminary results show that the features of the decorated ceramics have undergone dramatic variations when transmitted from a production to another, not only, as expected, in the composition of terracotta and glazes, but also in the thickness, the structure and the composition distribution of the lustre layers

Ceramics with metallic lustre decoration. A detailed knowledge of Islamic productions from 9th century until Renaissance

This paper describes research on the technological evolution of glazed ceramics with a metallic lustre decoration starting from their emergence in the Near East until the Hispano-Moresque productions. That research covers the main known Islamic production sites and periods: Abbasid (Mesopotamia); Fatimid (Egypt); Timurid, Mongol, and Safavid (Iran); Ayyubid and Mamluk (Syria); Nasrid and Hispano-Moresque (Spain). It was allowed by the access to more than hundred full preserved objects or fragments supplied by French national museums (Mus\'ee du Louvre DAI, Mus\'ee national du Moyen Age, Mus\'ee national de C\'eramique). The characterisation of the composition and structure of the ceramics and of their decoration is mostly done through non-destructive analyses methods. The thickness and metal content of the surface lustre layers are quantified thanks to ion beam analyses performed on a particle accelerator: PIXE (particle-induced X-ray emission) for the terracotta and glazes composition and RBS (Rutherford backscattering spectrometry) for the thickness and metal content of the lustre surface layers. The preliminary results show that the features of the decorated ceramics have undergone dramatic variations when transmitted from a production to another, not only, as expected, in the composition of terracotta and glazes, but also in the thickness, the structure and the composition distribution of the lustre layers.Comment: 23 pages ; non-destructive IBA analyses of more than 120 objects (fragments or entire objects) from all origins in the Islamic world and from 9th century to 18th centur

Dendritic Cell-Mediated-Immunization with Xenogenic PrP and Adenoviral Vectors Breaks Tolerance and Prolongs Mice Survival against Experimental Scrapie

In prion diseases, PrPc, a widely expressed protein, is transformed into a pathogenic form called PrPSc, which is in itself infectious. Antibodies directed against PrPc have been shown to inhibit PrPc to PrPSc conversion in vitro and protect in vivo from disease. Other effectors with potential to eliminate PrPSc-producing cells are cytotoxic T cells directed against PrP-derived peptides but their ability to protect or to induce deleterious autoimmune reactions is not known. The natural tolerance to PrPc makes difficult to raise efficient adaptive responses. To break tolerance, adenovirus (Ad) encoding human PrP (hPrP) or control Ad were administered to wild-type mice by direct injection or by transfer of Ad-transduced dendritic cells (DCs). Control Ad-transduced DCs from Tg650 mice overexpressing hPrP were also used for immunization. DC-mediated but not direct administration of AdhPrP elicited antibodies that bound to murine native PrPc. Frequencies of PrP-specific IFNγ-secreting T cells were low and in vivo lytic activity only targeted cells strongly expressing hPrP. Immunohistochemical analysis revealed that CD3+ T cell infiltration was similar in the brain of vaccinated and unvaccinated 139A-infected mice suggesting the absence of autoimmune reactions. Early splenic PrPSc replication was strongly inhibited ten weeks post infection and mean survival time prolonged from 209 days in untreated 139A-infected mice to 246 days in mice vaccinated with DCs expressing the hPrP. The efficacy appeared to be associated with antibody but not with cytotoxic cell-mediated PrP-specific responses