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The ongoing conservation of the Ghent Altarpiece 2012-2015

Anne Van Grevenstein

Résumés

Le polyptyque de l’Agneau Mystique a survécu une histoire violente et divers traitements dans le passé ont laissé leurs traces. L’approche interdisciplinaire du traitement de 1950-51 est encore aujourd’hui exemplaire pour le traitement entamé en 2012 par l’équipe de l’IRPA. Roger Marijnissen a participé à la recherche, et a suivi de près les deux traitements.

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Texte intégral

Many thanks to Hélène Dubois for reading this article and for making sound suggestions.

Introduction

1Roger Marijnissen has been working for a long time at the “Royal Institute for Cultural heritage” (KIK-IRPA, Brussels), one of the world’s most famous founding institutes for interdisciplinary collaboration in art conservation. He has experienced many times how difficult it can be to walk on the bridge between art historians, conservators and scientists and when conflicts arose he has chosen the role of “writing about problems”. It is, to my opinion, a way that rarely solves them. Meeting and talking in front of the object, listening, looking and evaluating together the interpretation of data seems to be more and more the way towards decision making in conservation matters today. R. Marijnissen wrote about many dilemma’s, bringing them under attention and in that sense, his contribution to the passage from polite acceptance and written controversies, towards open discussion in our field, has been very important.

The 1950-1951 campaign

2After the 2nd world war and just before the restoration campaign of the Ghent altarpiece in 1950-51, a major “cleaning controversy” was brought about by the treatment of paintings in the National Gallery of London. The discussions about total cleaning and total retouching, the Anglo Saxon school, versus respect for the value of age and patina, the Italian school, was still raging. At the onset of the conservation of the Ghent altarpiece, Paul Coremans, director of the Brussels Institute, brought international experts together to try and reach a consensus about treatment policies. Amongst others he invited Cesare Brandi, the director of the Istituto Centrale del Restauro in Rome, but also Sir Philip Hendy, head of collections at the National Gallery in London. They were strong opponents on the issue of varnish removal. Many discussions followed, carefully registered and annotated.

  • 1  P.COREMANS, L’Agneau Mystique au Laboratoire,1953, Anvers, De Sikkel, p.9 -10:  « Ce traitement, n (...)

3Consensus was reached under the motto that conservation was the primary goal of the treatment and that varnish should be removed to facilitate the consolidation of delaminating paint layers. Restoration i.e. removal old overpaint and discoloured retouching was allowed only if safety  was guaranteed.1

Chemistry and historical context

4Many paint samples were taken and analysed by the chemical laboratories. Technical documentation with ultra-violet, infra-red and x-rays was carried out and Coremans asked his conservator, Albert Philippot to explain and define the treatment he was applying to the paint layers.  

  • 2  P.COREMANS, L’Agneau Mystique au Laboratoire,1953, Anvers, De Sikkel,ibidem, "Histoire Matérielle" (...)

5R.Marijnissen and A.De Schryver did archival research to bring the “material history” closer to the scientists who were looking at the stratigraphy of paint layers. Interventions of the past could be dated hypothetically and the decision making process during conservation was placed within a historic framework. A first and important step towards understanding the historic meaning of interventions from the past could be made and their relative values assessed.2

6But many problems regarding the Ghent altarpiece remained unsolved at the date of publishing the results of interdisciplinary research in 1953. The questions about “who of the Brothers Van Eyck did what?” in the Ghent altarpiece remained unanswered in spite of the fact that cross sections showed a complex and multi layered paint structure. Most importantly, Coremans stated in his introduction that the pressure to complete the treatment on time, was the main cause for leaving questions unanswered. Research into the complexity of the paint structure with many unanswered questions about past treatments demands building a vital bridge between the material reality of the object observed by conservators, archival sources, analysis of materials and art historical interpretation. This was, and still is, a highly time consuming form of research.

Overview on a new campaign

7This was felt strongly during the present restoration campaign that was started by the KIK-IRPA team in October 2012.  By the middle of 2014, after the removal of many layers of yellow varnish, large areas of very old overpaint on the outside of the altarpiece were discovered and diagnosed as not original. The experience was shocking and confrontational, but it also gave a clear perspective for further research and it helped us all realise, once again, that our diagnostic vision is linked to the availability of onsite instrumentation during treatment. The data however needs to be assessed through careful observation and interpreted in its historic context. Interdisciplinary dialogue in front of the object is therefore of the greatest importance. Machines alone can never give unequivocal answers.

8The conservator in the past was often working alone, removing layers that had been applied by his predecessors and discovering “original” materials. He could hide his own mistakes and was naturally dependent of what he could actually see. Moving from working with the naked eye, using a magnifying glass and research microscope for taking paint samples, towards a stereo-microscope to observe the surface and control operations during treatment, progress made over the past sixty years has been spectacular.  

9The hierarchy of space distribution for working in museums usually placed the conservator  in the cellar or the attic, far from the scrutiny of art historians and even further from the laboratories generating data about the materials he was working on. The distance between the surface of the paint and a cross-section under a microscope was immense, as was the distance between the museum visitors and information about what was happening to the paintings they admired so much.The “Royal Institute” in Brussels improved vastly this situation by achieving a new synergetic working space where conservators, chemists and art-historians worked close to each other. Their deep investment in the publications of interdisciplinary research but also by making exhibitions for a broad dissemination of knowledge, such as the Brussels 1951 exhibition on the restoration of the Ghent altarpiece, was remarkable. (note: Palais des Beaux-Arts/Museum of Fine Arts, didactic exhibition with photographs, reconstructions and information about the conservation)

  • 3  P.COREMANS, L’Agneau Mystique au Laboratoire,1953, Anvers, De Sikkel, ibidem, pl. XXXIII, « Dégage (...)

10Improvement in the vision of the conservator was obviously achieved by progress in microscopic technology. A photograph of Albert Philippot at work with a microscope is shown (Fig.1 ) with the underlying text: “Uncovering of the original, under the mass of clouds: the union between magnification by the microscope and the tactile sensitivity of the conservator is often better than the best chemical solvents.” 3 (transl. AvG)

Fig.1 Albert Philippot

Fig.1 Albert Philippot

Albert Philippot during the removal of layers of overpaint on the sky of the central panel “The Adoration of the Lamb” (Plate XXXIII of L’Agneau mystique au laboratoire)

Credits:  KIK-IRPA, Brussels

11On the “macro photography in normal light, 5x”, (Fig.2) one sees the surface of the paint, during removal of overpaints and there, it is very difficult to distinguish, in the many layered structure of delaminating paint, the Van Eyck paint layers from later additions. It is furthermore impossible to assess if the losses are due to the scalpel or to the impact of time. It would take another twenty more years before a stereo-microscope, as used by surgeons in the medical world, could be used by conservators.

Fig.2 Macrophotograph in normal light P

Fig.2 Macrophotograph in normal light P

Macrophotograph in normal light, 5 x ( Pl.XLII bis of L’Agneau mystique au laboratoire).

Credits: KIK-IRPA, Brussels

12Today the link between seeing, understanding, measuring and the diagnosis about what is original and what not, is stronger than ever.                                          

13During the urgent conservation of the Ghent altarpiece in St Bavo Cathedral, 2010-2011, a stereo-microscope on loan from Ghent University was used to inspect the paint surface. (Fig.3 and4). Delamination was documented but the diagnosis of extensive overpaint was not made because they were still hidden under many layers of oxidised varnishes. And again, as in 1950, time pressure prevented in depth research into the structure of the paint layers.

Fig.3 Urgent conservation, 2010

Fig.3 Urgent conservation, 2010

Hélène Dubois using a stereo-microscope (UGent) to elaborate a prognosis for future conservation strategies. The identification of large layers of overpaint was impossible due to the presence of  numerous varnish layers on the paint surface.

Credits: Sint-Baafskathedraal Gent - Lukasweb.be-Art in Flanders vzw, photo by the author

Fig.4: Micro-photograph

Fig.4: Micro-photograph

Micro-photograph, of the paint surface of the Archangel Gabriel, magnification 35x.

Credits: Sint-Baafskathedraal Gent - Lukasweb.be - Art in Flanders vzw, Photo KIK-IRPA

14In the first year of the conservation project, it became more and more clear that interdisciplinary collaboration between the team of conservators, other KIK-IRPA departments and research teams outside was crucial. To realise that one institute with many departments needs moments of trans-departmental concentration is one thing. To bring research groups from different universities, usually in strong competition with each other regarding research subsidies, to work together is quite another issue, but can work.

15Ghent University harbours the GOA project that promotes interdisciplinary research projects between the faculties of humanities and exact sciences. Within this context four PhD posts, three conservation scientists and one conservator, were made available for research on the Ghent altarpiece. To facilitate non-destructive analytical methods, a 3-D Hirox microscope was purchased and made available to the team of conservators.

Fig. 5 Hélène Dubois (KIK-IRPA team and Ghent University) and Max Martens (Ghent University, GOA project)

Fig. 5 Hélène Dubois (KIK-IRPA team and Ghent University) and Max Martens (Ghent University, GOA project)

During the present restoration campaign, the paint surface was examined extensively after varnish removal with a 3-D digital microscope. Meeting in front of the paintings and interpreting the highly complex data provided by this type of high magnification  contributed to the validation of  hypotheses regarding original and non original overpaints.

Credits: Sint-Baafskathedraal Gent - Lukasweb.be - Art in Flanders vzw, foto by the author

Fig.6 Photomicrograph in raking light

Fig.6 Photomicrograph in raking light

A photomicrograph in raking light, taken with the Hirox microscope, magnification 100 X, shows the layer structure of the original paint layers and old overpaints with intermediate layers of varnish

Credits: Sint-Baafskathedraal Gent - Lukasweb.be - Art in Flanders vzw, photo KIK-IRPA/UGent

16Progress in vision and understanding of complex paint layers, but most of all the possibility to characterise these layers over a large surface, are essential.

17The University of Antwerp harbours the AXES research group that developed the Macro-XRF method of visualising elements in the paint by X-ray fluorescence and producing a mapping of the paint surface with ICT methods. This method is non-destructive, as opposed to paint sampling, and helps greatly in recognising material features of the paint   layers, hidden under overpaint, that cannot be detected by X-ray or Infra-red documents.

18Jana Sanyova from the KIK-IRPA laboratories  developed methodologies to re-examine with new technologies the paint samples taken in 1950-51 thanks to a research project subsidised by the “Belgian Federal Science Policy Office” (BELSPO) and the laboratories analysed new samples essential to answer new questions regarding the stratigraphy of paint layers and their dating. Urgent additional research on the paint samples was also funded by the Gieskes-Strijbisfonds. On the art-historical side,the  KIK-IRPA “Centre for the Study of Flemish Primitives” carries out  a  comparative documentation  with scientific imagery  on paintings by the Van Eyck group (VERONA project).

Conclusion

19This overview of ongoing research is not exhaustive but it shows that the complexity of problems related to the Mystic Lamb demands collaboration and joining forces. It demands listening to each other and looking together at the object, instead of fighting with words, safely from behind a writing machine or, as today, a computer.

20Over the past few years, the treatment of the Ghent Altarpiece has been followed step by step by an advisory committee. A group of international experts is invited on a regular basis to help with the decision making process. The team of eight conservators forms a strong basis for cross-border discussions, in a very fertile, constructive progression of remarks and discoveries. The conservator is not alone anymore and the increase of academic research by these professionals allows for deeper  and more complex exchanges with other fields.

21The Getty Foundation funded the worldwide dissemination of technical information on the website http://closertovaneyck.kikirpa.be,there is transparency in the Museum of Fine Arts in Ghent as visitors can follow the work in progress and exhibitions about the Ghent altarpiece are organised in the Provincial Culture Centre Caermersklooster.

  • 4  E.GOMBRICH, Art and Illusion, ed. Phaidon, 1959, p.51

22All this serves the same purpose: to create a solid basis for care in the future, by informing and thus involving all people concerned. We certainly hope that it will help alleviating mistrust and contra productive controversies about the treatment of the Ghent altarpiece. The remark published by Ernst Gombrich in 1959 “I fear it is in the nature of things that the historian will always be distrustful of the man of action in these difficult and delicate matters” could in the coming years, slowly fade away and be replaced by efficient dialogue.4

23Recently Roger Marijnissen has given all his archival material to the Museum of Fine Arts in Ghent. He is informed and participates in some of the discussions around the Ghent altarpiece. Sometimes we meet in the museum and he gives us sound advises, based on many, many years of experience. This is invaluable, and very peaceful indeed…  

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Notes

1  P.COREMANS, L’Agneau Mystique au Laboratoire,1953, Anvers, De Sikkel, p.9 -10:  « Ce traitement, nous l’avons défini comme une opération de nature technique visant à assurer la conservation de l’œuvre avec un minimum de restauration, dans le respect le plus strict de son intégrité historique et esthétique. Présentée le 10 novembre 1950, cette formule nouvelle fut discutée en détail, puis adoptée à l’unanimité par les membres de la Commission internationale d’experts. » 

2  P.COREMANS, L’Agneau Mystique au Laboratoire,1953, Anvers, De Sikkel,ibidem, "Histoire Matérielle" p.21-68.

3  P.COREMANS, L’Agneau Mystique au Laboratoire,1953, Anvers, De Sikkel, ibidem, pl. XXXIII, « Dégagement de l’original sous la masse des nuages: l’union du grossissement du microscope à la sensibilité tactile de l’opérateur est souvent préférable aux meilleurs réactifs chimiques. »

4  E.GOMBRICH, Art and Illusion, ed. Phaidon, 1959, p.51

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Table des illustrations

Titre Fig.1 Albert Philippot
Légende Albert Philippot during the removal of layers of overpaint on the sky of the central panel “The Adoration of the Lamb” (Plate XXXIII of L’Agneau mystique au laboratoire)
Crédits Credits:  KIK-IRPA, Brussels
URL http://ceroart.revues.org/docannexe/image/4625/img-1.jpg
Fichier image/jpeg, 2,2M
Titre Fig.2 Macrophotograph in normal light P
Légende Macrophotograph in normal light, 5 x ( Pl.XLII bis of L’Agneau mystique au laboratoire).
Crédits Credits: KIK-IRPA, Brussels
URL http://ceroart.revues.org/docannexe/image/4625/img-2.jpg
Fichier image/jpeg, 160k
Titre Fig.3 Urgent conservation, 2010
Légende Hélène Dubois using a stereo-microscope (UGent) to elaborate a prognosis for future conservation strategies. The identification of large layers of overpaint was impossible due to the presence of  numerous varnish layers on the paint surface.
Crédits Credits: Sint-Baafskathedraal Gent - Lukasweb.be-Art in Flanders vzw, photo by the author
URL http://ceroart.revues.org/docannexe/image/4625/img-3.jpg
Fichier image/jpeg, 3,2M
Titre Fig.4: Micro-photograph
Légende Micro-photograph, of the paint surface of the Archangel Gabriel, magnification 35x.
Crédits Credits: Sint-Baafskathedraal Gent - Lukasweb.be - Art in Flanders vzw, Photo KIK-IRPA
URL http://ceroart.revues.org/docannexe/image/4625/img-4.jpg
Fichier image/jpeg, 192k
Titre Fig. 5 Hélène Dubois (KIK-IRPA team and Ghent University) and Max Martens (Ghent University, GOA project)
Légende During the present restoration campaign, the paint surface was examined extensively after varnish removal with a 3-D digital microscope. Meeting in front of the paintings and interpreting the highly complex data provided by this type of high magnification  contributed to the validation of  hypotheses regarding original and non original overpaints.
Crédits Credits: Sint-Baafskathedraal Gent - Lukasweb.be - Art in Flanders vzw, foto by the author
URL http://ceroart.revues.org/docannexe/image/4625/img-5.jpg
Fichier image/jpeg, 5,7M
Titre Fig.6 Photomicrograph in raking light
Légende A photomicrograph in raking light, taken with the Hirox microscope, magnification 100 X, shows the layer structure of the original paint layers and old overpaints with intermediate layers of varnish
Crédits Credits: Sint-Baafskathedraal Gent - Lukasweb.be - Art in Flanders vzw, photo KIK-IRPA/UGent
URL http://ceroart.revues.org/docannexe/image/4625/img-6.jpg
Fichier image/jpeg, 1,5M
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Pour citer cet article

Référence électronique

Anne Van Grevenstein, « The ongoing conservation of the Ghent Altarpiece 2012-2015 », CeROArt [En ligne],  | Juin 2015, mis en ligne le 05 juin 2015, consulté le 08 décembre 2016. URL : http://ceroart.revues.org/4625

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Auteur

Anne Van Grevenstein

Trained as a restorer at IRPA and the Istituto Centrale del Restauro, Anne van Grevenstein specialised in the treatment of paintings, polychrome sculpture and historic interiors. She funded the Restauratie Atelier Limburg (Maastricht)and was it’s director until 2008. In 2005 she initiated the chair in The practice of conservation and restoration at the University of Amsterdam. She is now retired and became Advisor of the Churchwardens of St Bavo Cathedral.

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Droits d’auteur

Licence Creative Commons
CeROArt – Conservation, exposition, restauration d'objets d'arts est mis à disposition selon les termes de la licence Creative Commons Attribution - Pas d'Utilisation Commerciale - Pas de Modification 4.0 International.

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