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Between 2002 and 2006, sixteenth century monumental panel paintings from the Charola of the Convent of Christ in Tomar were submitted to conservation and restoration campaigns. The aim of this paper is to describe the historical context, aspects related to artistic techniques, conservation procedures and the materials used in the treatment of these works of art. The activities were undertaken in two phases: the first, under a project of the Instituto Português de Conservação e Restauro (IPCR) and a second, by the initiative of the Instituto Português do Património Arquitectónico (IPPAR).
Introduction
In 2002, the Instituto Português de Conservação e Restauro (IPCR) created a two-year project, sponsored by the Operational Programme for Culture (POC), for research and conservation of the panel paintings from Charola in Tomar (Figure 1). This initiative was developed by a large team of conservator-restorers, photographers, art historians, physicists, chemists and biologists, who studied the following works: "Baptism of Christ", "Resurrection of Lazarus", "Entrance of Christ in Jerusalem", "Instruments of Martyrdom" and "The Virgin and the Apostles". This program concluded with the intervention on the painting "Baptism of Christ" as well as on a small fragment salvaged from a lost panel "Instruments of Martyrdom". The “Resurrection of Lazarus" was not completed due to severe structural problems of its support [1]. Between 2004 and 2006, by the initiative of IPPAR and the Director of the Convent of Christ Dr. Jorge Custódio, the work was continued according to the same conservation criteria. The success of this work made possible to place back the panels into their own original niches. The objective of this text, presented publicly at the 2nd Conference of the Professional Association of Conservator-restorers of Portugal (ARP), "The Practice of Theory" (29 and 30 May 2009), is to disseminate the intervention procedures performed on the support and paint layers, indicating the methodologies and materials used. In the first phase of the work, problems in the supports were addressed by panel paintings conservator Miguel Garcia, and his master Pedro Correia, and the chromatic layer was treated by conservators-restorers Frederico Henriques and Sónia Pires. In the second phase, the treatment of the support and the chromatic layer was performed by conservator-restorers Frederico Henriques and Ana Bailão. Art Historical Context: the ‘Charola’ Panels The monumental panels of the Charola are probably the biggest sixteenth century works produced at the time of king D. Manuel I (1469-1521). The panels are attributed by Portuguese historiography, but with some doubts, to painter Jorge Afonso. The paintings are originally distributed through a deambulatory of twelve niches, representing the Life of Christ. At the present, though, only five complete panels and three fragments exist. The intervention was carried out on two complete paintings and three fragments, in the following sequence: "Resurrection of Lazarus", "Entrance of Christ into Jerusalem", "Baptism of Christ", "The Virgin and the Apostles" and "Instruments of Martyrdom" (Figure 2). The art historical context of the Operational Programme for Culture (POC) in this project was carried out by Dr. Pedro Redol and Dr. Amélia Casanova. Execution Techniques Naked eye and dendrochronological analyses supported the identification of the wood selected for the construction of the supports as oak from the forests of the Baltic region, most likely a “sessile oak” (Quercus petraea), a native species from that region. Dendrochronological analyses made by Dr. Peter Klein and Dr. Lília Esteves indicate the possible manufacturing of these paintings towards a period between 1488 and 1499. Each panel, measuring around 4 x 2,40 meters, is composed of 10 radial cut oak boards of 4 cm thickness disposed vertically (Figure 3). Their thickness was entirely thinned with adzes, whose marks are still present on the back. The boards are butt-joined (junta viva) and reinforced by square keys doubled pinned across the thick slats (taleiras) (Figures 4, 5, 6), a Flemish technological typology [2]. These are equidistant in 4 levels high. Comparative observation has shown that, the “Entrance of Christ into Jerusalem” panel follows more accurately this construction pattern. To get boards with the extensions of 4 meters high, the woodworkers used scarf joints, called in Portugal "empalmes". Here, two types of scarf joints were found: in bevel shape (in the Lazarus panel) and in “Z” shape (in all the other panels) (Figure 7). We concluded that the two different work techniques could in fact indicate the possibility of two independent carpentry workshops involved in this big project. The solid decorative oak black painted frames lock the whole panel in the slot and the entire system panel-frame is locked perfectly inside the niches through metal spikes nailed against the stone bricks.
From left to right:
Figure 1. View of Charola, the Convento de Cristo in Tomar. Figure 2. Drawing showing the location of the paintings in the deambulatory (© IGESPAR). Figure 3. Diagram of the painting construction: vertical oak boards and reinforcement cross-bars in orange. Figure 4. View of the wood dowels on the painting surface. Figure 5. View of the wood dowels on the back of the painting “Resurrection of Lazarus” and the shellac coverage. After an exhaustive photographic documentation in day light, infrared photography, ultraviolet fluorescence photography, infrared reflectography and X-rays made by Dr. Pedro Sousa and chemical analysis to the constituent materials performed by Dr. Carmo Serrano, the plans of action for the project were finally elaborated (Figure 8). There was a proposal for diagnosis and treatment. Apart from some exceptions, the methodologies were current conservation-restoration techniques that are commonly used in Portugal. The observation of the under-drawing observation was made with naked eye due to the increasing transparency of the painting caused by the natural aging of the materials and the various abrasions – and by infrared reflectography through digital recording. This was done with a Sony Handycam DCR PC115E PALTM in NightShot mode, with an infrared filter HoyaTM attached to the lenses. This video camera has provided images of excellent quality and high contrast (Figure 9) in relation to traditional systems such as infrared reflectography (vidicon), which was also tested, and infrared photography film. In a second phase a Sony Cybershot F-717TM digital camera (Figure 10) was used. Concerning the drawing technique, and in comparison with other examples [3] we can say that it was done by brush with carbon black on white ground layer.
From left to right:
Figure 6. Butt-joint reinforcement: floating key locked with a pair of dowels (or pins). Figure 7. Scarf joints found in the panel boards. Figure 8. General view during the photographic session (© Miguel Garcia). Figure 9. Registration of the underdrawing by infrared (video). Figure 10. Registration of the underdrawing by digital infrared photography. Radiography, for example, was essential to study the constructive techniques of the wood support in order to confirm issues concerning the conservation state of the works. It was possible to determine the existence of keys inside the butt-joints, the lines of the boards' scarf joints, the structural integrity of the slats, the location and level of decay of the wood, degraded by fungus and insect activity (Figure 12). Laser scanning was also used in the conservation project of the painting “Entrance of Christ in Jerusalem”, for the documentation the warp of the boards (Figure 13) [5]. The paintings were subjected to technical study in order to identify what is original [6], after which several well preserved marks were found on the back of the panels. These include carpenter tool marks and marks of inventory made in previous treatments, travels, etc. Of all marks, one inscription on the painting of “Entrance of Christ in Jerusalem” was selected. A recent study attempted the identification of inscriptions located on a crossbar, made with graphite on the back of the panel by the nineteenth-century restorer [7]. The method involved the application of tools of remote sensing: maximum likelihood classification and the elaboration of thematic classes (created polygons were classified as "inscription area", "wood background" and "screw"). This study allowed the reading of the inscription: "Foram acentes em 1868 Julho 23" meaning the reinforcement crossbars were subjected to restoration by July 23rd, 1868 (Figure 14). Another similar exercise was applied to determine a shellac area brushed widely on the back of the Lazarus panel. The results showed the presence of shellac on approximately 41% of the surface (Figure 15).
From left to right:
Figure 11. Example of stratigraphic layer (© IMC). Figure 12. Full size radiography of “Resurrection of Lazarus” (© IMC). Figure 13.Orthophotography made with laser infrared reflectance and topographic mapping (© Superfície-Geomática, Lda.) Figure 14. Inscription obtained by supervised classification. Figure 15. Shellac area detection by supervised classification (in black). Table 1 shows an explanatory framework in chronological order of some known interventions [8, 9].
Methodologies of Conservation-Restoration Intervention The methodology of conservation-restoration presented here briefly was performed on the wooden support and chromatic layer. Wooden support • Removal of the panels with removal of non-original parts and crossbars; • Disinfestations with liquid Permethrin-based biocide (CuprinolTM); • Mechanical cleaning of wood joints; • Volumetric reconstructions with the use of slim and flat trapezoidal Castanea sp. pieces in areas of cubical rot and some cracks; • Union of wood joints with polyvinyl acetate (Figure 16); • Replacement of the old crossbars by aluminum bars, which slide over small bridge sections of wooden blocks, connected themselves with a slim flat key of the same metal, creating a lighter structure and reinforcing the panel. The application and development of the system was previously studied [10]. The presented system is similar to the Carità model by Istituto Centrale del Restauro, in Rome, but it uses aluminum bars with rectangular section instead of circular shape section (Figures 17 and 18) [11]. Chromatic layer • Application of facing with diluted adhesive animal glue; • Testing the solubility of the aged resins and overpaintings. To this end, we used the protocol of cleaning polychromy of Masschelein-Kleiner [12] and the gel system formulated by Richard Wolbers [13, 14]. In all panels, the chemical cleaning of the varnish and overpaintings was made with a solvent gel (Propanol-2) (Figure 19). The laboratory information indicated that the coatings were shellac, thus, not originals. • The chosen material for gap-filling was the commercial product ModostucTM, in white color, due to its stability and elasticity properties. • The chromatic reintegration was initially made with gouache and watercolor Talens and Winsor & NewtonTM. The gouache was applied in most cases because of their opacity. After the saturation of colours with synthetic resin, the second phase was started with the use of powder pigments admixed in the same resin to match the colour of the gouache used as protective coating and finishing (Figure 20). This technique is very common in Portugal. • The application of protective layers was made according to the paintings. Two systems were used: one was the application of dammar resin in contact with the original paint layer followed by a sprayed layer of the copolymer Paraloid B72TM. In these cases the chromatic reintegration was done with acrylic synthetic resin dissolved in diacetone alcohol. The other consisted in using a commercial cyclohexanone resin as a retouching varnish. In such cases the chromatic reintegration was finished with pigment powder in the same resin that was used as a protective varnish.
From left to right:
Figures 16. The union of the wood joints (© Miguel Garcia). Figure 17. The new reinforcement system with cross aluminum bars. Figure 18. Detail of the new reinforcement system with cross aluminum bars. Figures 19 and 20. Cleaning of the varnish and retouching with gouache.
Conclusions
The main objective achieved with these projects, conducted and followed up by state institutions was the return of the panel paintings to their original location, the Charola. It is through such initiatives involving multidisciplinary teams that we can acquire and disseminate knowledge about cultural heritage (Figures 21, 22, 23). When we started this project, in 2002, the treatment of the support was frequently made, in Portugal, only by woodworkers. The painting conservator-restorer merely acted on the chromatic layer. This work has proved that the paintings conservator-restorer can undertake, with the proper knowledge, the support treatment as well. It is important that this form of understanding the intervention of conservation-restoration in panel paintings becomes a common practice in Portugal, since only a conservator-restorer is aware of general problems of the work. Woodworkers do not interpret the painting as a whole, but try to collaborate in solving the problems of wood support. This unique collection of panel paintings represented a conservation challenge that was successfully met due to the highest standard of scientific collaboration between all the project participants. From left to right: Figure 21. General view of “Resurrection of Lazarus” after the intervention. Figure 22. General view of “Entrance of Christ in Jerusalem” after intervention. Figure 23. General view of “Batism of Christ” after the intervention. The authors would like to thank to the ex-Director of Convento de Cristo Dr. Jorge Custódio, to Pedro Correia, Rui Ferreira, Paulo Henrique, Júlio Calafate and to the other employees of Convento de Cristo; Fernando Antunes of the Polythecnic Institute of Tomar (IPT); Dr. Alexandre Gonçalves, Instituto Superior Técnico (IST); Instituto dos Museus e da Conservação (IMC); and Instituto de Gestão do Património Arquitectónico e Arqueológico (IGESPAR). This work has been supported by Fundação para a Ciência e a Tecnologia (FCT) and Programa Operacional Ciência e Inovação 2010 (POCI 2010), co-funded by the Portuguese Government and European Union by FEDER Program. This research was also partially supported by FCT scholarship SFRH /BD/42488/2007. References [1] A. I. Seruya and M. Pereira (dir.), As Tábuas da Charola, IPCR, Lisboa, 2005 [2] H. Verougstraete-Marcq and R.Van Schoute, Cadres et supports dans la peinture flamande aux 15e et 16 siècles, Heure-le-Romain, 1989 [3] D. Bonford (ed.), Art in the making: Underdrawings in Renaissance paintings, National Gallery Publications, London, 1992 [4] L. Masschelein-Keiner, Liants, Vernis et Adhésies Anciens, Institut Royal du Patrimoine Artistique, Brussels, 1978 [5] H. Pires, F. Henriques, P. Marques, Novas fronteiras no registo e diagnóstico de pinturas retabulares. A utilização dos sistemas de varrimento laser, in Pedra & Cal, nº 33, Janeiro, Fevereiro, Março, 2007, pp. 20-22 [6] A. Bailão and F. Henriques, "Cleaning and retouching on paintings in Portugal: Historical and ethical issues in the last two decades of 20th century", in La Restauración en el Siglo XXI. Función, Estética e Imagen. Actas del IV Congreso, Grupo Espanol del IIC, Cáceres, 2009, pp. 311-318 [7] F. Henriques, A. Gonçalves, A. Calvo, A. Bailão "Application of spatial analysis operations for the characterization of wood painting features", in COST Action IE0601- Evaluation of Deterioration and Management of Change. Wood Science for Conservation of Cultural Heritage, URL [pdf] (accessed 26th April 2010) [8] Anais da União dos Amigos da Ordem do Convento de Cristo (UAMOC), Vol. 1, Tipografia António Gouveia, Tomar, 1941 [9] Anais da União dos Amigos da Ordem do Convento de Cristo (UAMOC), Vol. 2, Imprensa Lucas &, Lisboa, 1946 [10] F. Henriques, Conservação e Restauro de Estruturas e Suportes em Madeira na Pintura de Cavalete, Instituto Politécnico de Tomar, Departamento de Arte, Conservação e Restauro, Tomar, 2005, final report of licenciatura degree [11] S. Bergeon, G. Emile-Mâle, C. Huot and O. Baÿ, "The Restoration of Wooden Painting Supports: Two Hundred Years of History in France", in K. Dardes and A. Rothe (ed.), The Structural Conservation of Panel Paintings, The Getty Conservation Institute, Los Angeles, 1995, pp. 264-288 [12] L. Masschelein-Kleiner, Les Solvents, IRPA, Bruxelles, 1981 [13] R. Wolbers, Cleaning Painted Surfaces – Aqueous Methods, Archetype Publications, London, 2000 [14] P. Cremonesi, Materiali e Metodi per la Pulitura di Opere Policrome, Phase, Bologna, 1997
About the authors
Frederico Henriques
Conservator-restorerContact: frederico.painting.conservator@gmail.com Frederico Henriques has a Bachelor in Conser-vation and Restoration by the Higher School of Conservation and Restoration of Lisbon (1997) and a licenciatura degree in Conservation and Restoration by the Polytechnic Institute of Tomar (2005). He is currently a PhD candidate in the Conservation of Paintings at the Portuguese Cath-olic University in collaboration with the Department of Civil Engineering and Architecture, Section of Systems Support Project, of the Instituto Superior Técnico. The PhD dissertation is being supervised by professors Ana Calvo and Alexandre Gonçalves and is funded by Fundação para a Ciência e Tecnologia.
Ana Bailão
Conservator-restorerContact: ana.bailao@gmail.com Ana Bailão graduated in Conservation and Restoration by the Polytechnic Institute of Tomar (2005) and has a master in Conservation of Cultural Property, in the area of Painting, from the Portuguese Catholic University (2010), where she is currently a PhD candidate in Conservation of Paintings. Her objective is to study methodologies to enhance the quality of painting retouching. At the present she practices conservation and restoration since 2004 in her own studio.
Miguel Garcia
Conservator-restorerContact: miguelalexgarcia@gmail.com Miguel Garcia has a Bachelor Degree in Conservation and Restoration, Furniture Area, by the Higher School of Conservation and Restoration of Lisbon (2002). Thereafter he has participated in several projects among which a 2002/2004 project in the Conservation of Panel Paintings specialty, through the orientation of IPCR, Lisbon; a brief participation in the projects Wrightsman Galleries for French Decorative Arts, and Wisteria Room for 19th and 20th century Galleries, both at the Metropolitan Museum of Art; and the Spanish Ceiling Project for the Islamic Galleries of the Metropolitan Museum of Art, New York, from August 2007 to June 2009.
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