Plaster Casts of the Works of Arthistory of collections

– conservation – exhibition practice

From the series: The National Museum in Krakow Studies and Research Materials

Plaster Casts of the Works of Arthistory of collections

– conservation – exhibition practice

Materials from the conference in The National Museum in KrakowMay 25, 2010

Krakow 2010

Conference

Conference accompanying the exhibition “Krakow Within Your Reach. Architectural Sculpture in the Collection of the National Museum in Krakow” in the National Museum in Krakow – The Bishop Erazm Ciołek Palace, The Hall of Virtues, May 25, 2010

Project financed in part by the European Regional Development Fund as part of the Małopolska Regional Operational Programme for the years 2007 – 2013 (Priority Axis 3. Tourism and Culture industry, Action 3.3. Cultural institutions, Scheme B: Organisation of cultural events of regional and transregional significance)

Project was realized with the financial support of the Ministry of Culture and National Heritage

Organisation: Marek MrózCollaboration: Wojciech Marcinkowski, Tomasz Zaucha

Publisher

Scholary editor: Wojciech Marcinkowski, Tomasz ZauchaLeading editor: Marta OrczykowskaCollaboration: Krystyna StefaniakGraphic design / dtp: Piotr KosteckiPrinted by: Drukarnia expol, WłocławekPhotos: Michał ObarzanowskiPhoto 6: Piotr Fronczek

On the cover: The Antique School of the Royal Academy of Arts at New Somerset House, c. 1780 – 1783, Photo © Royal Academy of ArtsOn p. 6:The Bishop Erazm Ciołek Palace – Branch of The National Museum in Krakow

© Muzeum Narodowe w Krakowie 2010ISBN 978-83-7581-059-2

Media Patrons:

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Table of Contents

Zofia Gołubiew

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Jean-Marc Hofman The cast collection of the Musée des Monuments Français (Paris). A panegyric of the French heritage

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Milena Melfi Old meets New: the Oxford University collection of casts from the antique and the new Ashmolean Museum

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Hubert Kowalski The history of regal and university collection of plaster casts in Warsaw 30

Ivo Hlobil, Petr ChotěborOdlitky skulptur z katedrály sv. Víta v Praze 44

Steffi Roettgen Abbild und Urbild im Dialog: zur Abformung von Ghibertis “Porta di mezzo” 50

Wojciech Marcinkowski, Tomasz Zaucha An outline of the history of the collection of plaster casts at The National Museum in Krakow

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Anna Kłosowska, Michał ObarzanowskiPlaster casts in the collection of The National Museum in Krakow. Conservation issues

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hen we opened the exhibition Krakow Within Your Reach in May this year, we stressed that, as well as showing the public things of beauty, it was also to serve a scientific and educational purpose.

Thus over the months that the exhibition has been open to the public it has been ac-companied by a full and interesting educational programme which continues to run.The present publication is the fruit of an international academic conference devoted to collecting, conserving and exhibiting plaster casts in museums across the world.

The curator and coordinator of the exhibition and the conference, Dr Wojciech Marcinkowski, has outlined their aims, objectives and the subjects addressed in his preface. All that remains to me, then, is to thank both him and the director of the Bish-op Erazm Ciołek Palace, Marek Mróz, as well as all my other colleagues who were involved in the organisation of the conference. Above all, however, I must express my gratitude to those who took part in it, in particular those who gave papers. I would also like to reiterate my thanks to the Minister of Culture and National Heritage and the Marshal of the Małopolskie voivodship for their financial support of our project.

I hope that this, the fourth volume in our Museum’s series of academic publications, will, like its predecessors, find a sizeable readership and prove an important addition to the state of research into the history of Polish art.

Zofia Gołubiew

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n May 22, 2010, a new gallery was opened in the Bishop Erazm Ciołek Palace, a branch of the National Museum in Krakow: “Krakow within Your Reach. Architectural Sculpture from the Collections of the National

Museum in Krakow.” The exhibition includes around 100 fragments of stone, many of them the sole surviv-ing relics of non-extant buildings both sacral and secular. Others are originals that have been replaced in their original buildings by copies. Although many of these pieces represented a very high artistic standard, there was much greater visitor interest in the plaster casts and models. This was partly due to the simple fact that there were more of these – over 700 exhibits, filling five of the seven cellars under the northern and western wings of the Palace. This collection came into being for two reasons. Firstly the National Museum’s old-est permanent exhibitions in Krakow (in the Cloth Hall and the Town Hall Tower) featured plaster casts in place of works of architecture that were not available for display purposes but were considered essential elements of the museum narrative on the history of art in Poland. The main influx of plaster pieces to the Museum came as a result of the major conservation work undertaken on Krakow buildings, above all the Wawel Cathedral and St Mary’s Church, at the turn of the 19th and 20th centuries. Plaster casts were made at that time to document the state of preservation of particular works, while plaster models were used as patterns on which to base details that needed recarving. We decided that the character of our collection was sufficiently interesting to warrant a confrontation with the genesis of other important European collections of plaster pieces. The format on which we settled was an international conference, “Plaster Casts of the Works of Art. History of Collections – Conservation – Exhibition Practice”. The conference was held on May 25 in the Virtues Room on the first floor of the Bishop Erazm Ciołek Palace, and ten papers were given. Prof. Jerzy Miziołek (Institute of Archaeology, University of Warsaw) offered a historical overview of the subject of plaster cast collecting. Eryk Bunsch (Museum Palace in Wilanów) discussed the technical aspects of executing plaster casts. Next, Jean-Marc Hofman (Cité de l'architecture et du patrimoine / Musée des Monuments Français – Galerie des Moulages, Paris) described the new layout (2007) of the Paris collection of plaster

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casts. Dr Milena Melfi (University of Oxford, Ashmolean Museum, The Cast Gal-lery) also gave a paper on the layout of another fine collection of casts, in Oxford. University collections of plaster casts were also the subjects of the next two speakers, Dr Elena Mango (Universität Zürich – Archäologische Sammlung) and Dr Hubert Kowalski (Institute of Archaeology, University of Warsaw). A very special collec-tion of plaster casts all connected with one building – St Vitus’ Cathedral in Prague

– was profiled in a joint paper given by Prof. Ivo Hlobil (Ústav dějin umění av čr in Prague) and Dr Petr Chotěbor, Arch. Eng. (Správa Pražského hradu). The next paper, from Prof. Steffi Roettgen (Kunsthistorisches Institut Florenz – Max Planck Institut), was focused on a single work, Lorenzo Ghiberti’s Porta del Paradiso, and the casts from it. The conference was brought to a close with two papers by the authors of the exhibition in the Bishop Erazm Ciołek Palace. The present authors gave an out-line of the history and character of plaster casts in the National Museum in Krakow, while Anna Kłosowska and Michał Obarzanowski talked about the conservation of the collection. Unfortunately, for reasons beyond our control we were unable to publish three of the papers given in May 2010 in the present volume.

The National Museum in Krakow has undertaken something that in our region is still a groundbreaking task: the presentation of a large collection of plaster casts and models, the main body of which was made over a century ago. In the cata-logue accompanying the exhibition we pointed out that at present we have reined in our ambitions to summarising the state of research into this collection: preparing the ground for fuller studies, and identifying areas of uncertainty and emerging issues. The exhibition in the Bishop Erazm Ciołek Palace itself was conceived as a basis for further study, of which the present conference materials are the first fruits.

Wojciech Marcinkowski, Tomasz Zaucha

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Fig. 1. Tomb of Rafał Maciej Ocieski. A Condemned person devoured by beasts. Inv. no. mnk i-g-185. Window keystone, northern wall of the chancel. State of preservation before and after conservation

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Anna Kłosowska*, Michał Obarzanowski**

Plaster casts in the collection of the National Museum in Krakow. Conservation issues

The National Museum in Krakow, Department i – “Polish Painting and Sculpture Before 1764” – houses a collection of several hundred plaster casts, outstanding examples of 12th – 16th century sculptures, royal tombstones, architectural details important to Polish cultural heritage, executed at the break of the 19th and 20th centuries. They come from the Wawel Royal Castle, churches and historic houses in Krakow, and from other Polish cities. Some are the only existing records of lost originals.

These objects act as documentation of valuable pieces of Polish art. Despite this and their fragility, not much has ever been done for their protection. From the 1960s onwards they were kept in the Museum’s storerooms, forgotten and inaccessible to the public.The Sculpture Conservation Workshop in the National Museum in Krakow has prepared a collection of plaster casts for a new study storeroom designed and com-pleted as part of the “Krakow Within Your Reach” project.The first conservation works took place in 2005, but were boosted in autumn 2008 when the project was established and finalized in 2010. This allowed us to take up a complex approach to dealing with the conservation problems of the whole collec-tion, consisting of over 700 pieces. Each and every object had to undergo conserva-tion treatment of varying extent.Usually, plaster casts are seen as simple objects made of gypsum. This is a very general attitude. In practise, we find them with various finishes – raw, untreated plaster cast, monochromed, polychromed or gilded, with different inner constructions – wood, metal, fabric or hemp.So, from the restorers point of view, these are complicated objects made of different kinds of materials, posing a wide range of conservation problems.

* Head of Sculpture Conservation Workshop, The National Museum in Krakow, ul. Krupnicza 26, 31-123 Krakow, Poland, +48 12 3708196, aklosowska@muzeum.krakow.pl

** Conservator, Sculpture Conservation Workshop, National Museum in Krakow, ul. Krupnicza 26, 31-123 Kraków, Poland, +48 12 3708196, mobarzanowski@muzeum.krakow.pl

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The state of preservation before treatment and causes of damage

Damage occurred mainly due to bad storage conditions and inappropriate protec-tion and handling. Over the years, objects became heavily soiled, covered with a thick layer of dirt and dust (fig. 1, 2). The Museum’s cellars, where the objects were stored, and the objects themselves had been flooded several times and exposed to high relative humidity levels and long-term water activity, which caused migration of soiling material into the porous structure of plaster.Due to the fragility of the plaster itself and improper handling, especially during a number of dislocations, some of the objects were broken into fragments or heavily cracked, kept in one piece only by inner reinforcements (fig. 3, 4). In consequence, serious losses occurred and sometimes big fragments of sculptures were lost (fig. 5).

Fig. 2. St Florian’s basilica in Kleparz.

Three male busts. Inv. no. mnk i-g-159/1.

Half-figure above the wings, retable

in the Brethren’s chapel (of St Ann). State

of preservation during conservation.

Visible gilded and polychromed surface

partially cleaned

Fig. 3. Parish church of the Elevation of the Holy Cross in Zwoleń.

Bust of Jan Kochanow ski. Inv. no. mnk i-g-320. State of preservation

before and after conservation

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Fig. 4. Cathedral of the Assumption of the Virgin Mary in Gniezno. Panel of the Gniezno door. Scene iv. St Adalbert prays in front of the temple. Inv. no. mnk i-g-258/3. State of preservation during conservation. Object heavily cracked

Plaster is a fragile material, so on most occasions inner constructions are introduced during the casting process. Depending on size, shape and form, a range of materials can be used. Steel rods for limbs or other protruding elements, wooden frameworks for exterior supporting constructions, meshes made of metal, textile or tow for thin layered surfaces.These reinforcements improve the object’s durability and stability but, on the other hand, they react differently than plaster to environmental conditions, which may play a major role in the object’s destruction (fig. 6).

Corroded inner metal structures were observed in damaged areas. Corrosion products penetrating the porous structure of plaster became visible as extensive stains on the surface (fig. 7). Swelling of the rusted material caused cracking of the plaster.Deformation and damage of wooden supports caused further destruction due to alternating swelling and shrinking of the wood in changing rh (relative humidity) and temperature conditions (fig. 8).

Fig. 5. Tomb of king Ladislaus Jagiello, panel in baldachin soffitto. Triton (nw corner). Inv. no. mnk i-g-101. State of preservation before and after conservation

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Typical damage as a result of prolonged water activity was observed on several objects. It is obvious that on some occasions, water had been dripping on the cast’s surface for a long time, as it had hollowed out deep, distinctive cavities (fig. 9). Due to the specific relative humidity and temperature conditions in storage rooms, microbiological corrosion appeared on some objects (fig. 10). Species of fungi (Chætomium globosum, Chætomium murorum and Mortierella sp.), identified by Dr A. Chlebicki from the Mycology Department, Institute of Botany, Polish Academy of Sciences, suggest that the collection must have been flooded by the sew-age system as well. A great majority of the casts did not present signs of previous renovations, although some had been treated in a simple and provisional way, which in the long term proved to be a dubious and potentially dangerous procedure. For example, overpainting soiled surfaces instead of cleaning them, using irremov-able, penetrating paint, negligent plaster fillings and repairs.

Conservation treatment

The conservation treatment varied according to the state of preservation of the particular objects, and their manufacture technique.Thorough cleaning of the surface was the first step of the conservation treatment. It had to be completely safe for the object’s surface and relatively quick in terms of time planned during the Project. The cleaning methods were chosen after extensive tests, including many kinds of materials and methods, such as different kinds of rub-bers, micro sandblasting with very fine abrasives, for example, potato starch or col-loidal silica, cleaning with saturated solutions of calcium sulphate. Finally, a method that can be called “strappo”, when the surface is covered with a coat of a peeling-cleaning agent, which, while drying, forms an elastic coat that next can be peeled

Fig. 6. Tomb of king Ladislaus the Short

(Ladislaus the Elbow-High). Men in funeral

procession. Panel 5, southern side

of the tomb chest. Inv. no. mnk i-g-74.

X-ray photo showing inner metal construc-

tion of the cast

Fig. 7. Stain of corro-sion products from

a rusted steel bolt penetrating the porous

structure of plaster

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Fig. 8. Tomb of king Ladislaus Jagiello, panel of tomb chest. Inv. no. mnk i-g-86. Back side of the object with damaged wooden support

Fig. 9. Western part of the cathedral. Console of effigy of St Stanislas. Inv. no. mnk i-g-14. Typical damages of plaster as a result of prolonged water activity, deep cavities hollowed out by water drops

Fig. 10. Tomb of king Ladislaus Jagiello, King’s effigy. Inv. no. mnk i-g-84. Cluster of microorgan-isms at the back side of the object

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off the surface together with a layer of dust and dirt adhered to it. The best results were obtained by the last method. Different kinds of formulas were tested, including modified methylcellulose or starch-based pastes, modified polyvinyl acetate and modified latex. Remmers Arte Mundit type 1 latex, a self-vulcanising paste, proved to be the most satisfying cleaning agent.Before the application of latex, the surface of the plaster cast was carefully and pre-cisely dusted and vacuumed using soft brushes and Progress-Micro vacuum nozzles. Next, two coats of latex were applied one by one, after the first layer had dried (fig. 11). The vulcanized film was removed after approximately 6 to 12 hours, although it can be removed up to 3 days later, depending on environmental conditions (fig. 12). If needed, the latex application was repeated until the desired effect was obtained.This method showed to be time-consuming and quite expensive, so in some cases modified polyvinyl acetate was used where applicable. For example, on the reverse of objects or where the plaster structure was well preserved and durable. Unlike

Fig. 11. Architectural decoration (fragment),

18th cent. Inv. no. mnk i-g-354.

Application of Arte Mundid latex paste

Fig. 12. Architectural decoration (fragment),

18th cent. Inv. no. mnk i-g-354.

Removal of dried latex film

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in the case of latex, the drying process of polyvinyl acetate is extremely related to humidity and temperature, so it had to be strictly controlled and removed from the surface in a certain moment, before the film had fully dried. Otherwise the plaster surface could be damaged. Under these circumstances, modified polyvinyl acetate does not disturb the original surface and in most cases one coat was generally enough to obtain the expected effect ( fig. 13). This speeded up the cleaning process of the whole collection.The method described above was widely used for cleaning unfinished, raw plaster cast. Soiled polychromed or gilded casts were cleaned by means of chemical methods with different agents chosen after preliminary tests (fig. 2). Where possible, corroded steel bolts were replaced with stainless steel ones. Uncov-ered corroded metal fragments, impossible to remove or replace due to technical construction aspects, were derusted and covered with a protecting coat.Objects suspected of being infected by microorganisms (fungi, mold) were sprayed with a disinfecting agent. Clusters of microorganisms, after identification, were mechanically removed before disinfection.

All broken or cracked objects were reassembled and glued with the help of a reversible, synthetic resin base adhesive – Paraloid b 72 solution in acetone. Where necessary and possible, an inner stainless steel reinforcement was used (fig. 14).In some cases, an additional reinforcement was introduced, attached to the back of the objects. This happened with heavily broken, weakened or thin casts, where introduction of inner reinforcements could not be made, or where there was insuf-ficient physical endurance. These external supports were formed of laminates on intervention layers and /or an aluminium profile construction.

Fig. 13. Architectural decoration (fragment) 18th cent. Inv. no. mnk i-g-354. Comparison of latex and modified polyvinyl acetate after applica-tion and removal of one coat

Fig. 14. Tomb of king Ladislaus Jagiello, panel of tomb chest. Inv. no. mnk i-g-85. Stainless steel inner construction used as a support for plaster reconstruction

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First, an intervention layer of polyurethane foam or foamed polystyrene was applied on to the back of the objects. When the surface was curved or uneven, a coat of poly-urethane foam was applied (fig. 3, 15). After expansion and binding, the foam was cut down to an appropriate thickness. Next, a laminate consisting of woven fibreglass and a nonwoven polyester Coremat with microspheres, fully impregnated with epoxy resin, was applied directly onto the intervention layer (fig. 16).When the back of the object was flat, we used thin sheets of foamed polystyrene as an intervention layer. In such cases, a flat layer of laminate was prepared separately and then attached to the intervention layer (fig. 17).Laminates form a rigid support, keeping reattached parts in place and strengthen-ing the object. The intervention layer enables future detachment of the laminate, if necessary.Additional reinforcements of aluminium profiles were introduced separately as well as together with laminates. On a few occasions, it was necessary to remove old deformed wooden beams, no longer providing support. These were replaced by a specially designed external framework using the Bosch Rexroth aluminium profile system (fig. 18, 19). This allowed for the reattachment of broken parts of the object and the object’s safe handling and exhibition.As a general rule, it was decided that we should not restore any serious losses (miss-ing parts) of the casts. At first, it was not always certain whether these were losses of the cast itself or of the originals they were taken from. In some cases, the originals were accessible for com-parison, but we could not always be sure that their present state is authentic and not the result of former restoration works. And, most of all, we did not have sufficient time to analyse every case. This can always be done in the future.

Fig. 15. Parish church of the Elevation

of the Holy Cross in Zwoleń. Bust of Jan

Kochanowski. Inv. no. mnk i-g-320.

A coat of expanded polyurethane foam

applied at the back side of the object as an intervention layer

before surface treatment

Fig. 16. Parish church of the Elevation

of the Holy Cross in Zwoleń. Bust of Jan

Kochanowski. Inv. no. mnk i-g-320.

Laminate attached to the back side

of the object

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Fig. 17. Panel of the Gniezno door. Back side of the object with laminate made on foamed polystyrene sheet as an interven-tion layer

Fig. 18. Tomb of king Ladislaus Jagiello, panel of tomb chest. Inv. no. mnk i-g-86. Back side of the object with damaged wooden support

Fig. 19. Tomb of king Ladislaus Jagiello, panel of tomb chest. Inv. no. mnk i-g-86. Aluminium profile system supporting attached pedestal

We reconstructed only losses which were undoubtedly mechanical damages of the casts and were unacceptable from the aesthetic point of view (fig. 20), or when construction repairs were necessary, when there was no direct connection between two preserved elements and big fragments of the cast were lost. Existing fragments were joined with stainless steel bolts leaving an appropriate gap, fibreglass fabric reinforcement was used as support for the plaster filling, made in a neutral way, with-out having to reconstruct the original sculpture (fig. 21). All losses along the joints of attached fragments were restored. When necessary, fillings were retouched with reversible mineral paint with powdered pigments.Necessary retouches were also made on painted and polychromed objects. Stains from corroded inner structures were also retouched.The last stage of the conservation works was the application of a protecting coat, dependent on the surface finish. For this we used white talcum powder, Remmers Funcosil ow or varnish and microcrystalline wax.

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Essential conservation treatment of the whole collection was performed to stop the degradation processes and eliminated main destruction sources. Despite the fact that the scope of work and limited time did not allow for detailed case studies of each and every object, we were able to handle all objects so they are safe to exhibit and store. Now, to maintain its present condition, a proper preventive conservation policy has been applied. As the “Krakow Within Your Reach” exhibition and study storeroom is organized in a historical cellar complex in the Bishop Erazm Ciołek Gothic and Renaissance palace, the rh levels need to be continuously monitored and maintained by means of special equipment. All objects are kept in intentionally designed sealed cabinets, showcases and freestanding, fully glazed kiosks with inner shelve systems. This helps to keep environmental conditions at acceptable levels and minimises the deposition of dust and other particles. The way for future conservation, based on more detailed studies and research is always open. We are aware that our work was in some terms basic and some particular objects might want to be further handled.

Fig. 21. Tomb of king Ladislaus Jagiello,

panel of tomb chest. Inv. no. mnk i-g-88.

Existing fragments reattached with help

of stainless steel bolts, missing fragment

reconstructed on a fibreglass mesh

and stainless steel bolts

Fig. 20. Tondo with a half-figure of king

Salomon. Relief from the southern (throne)

wall inside the Sigis-mund chapel.

Inv. no. mnk i-g-66. State of preservation

before and after conservation