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This paper discusses the conservation project of the exterior frescoes from Coltea Church, a 17th century monument from Bucharest. Located in the centre of the capital, the church was subjected to extremely aggressive deterioration factors that induced advanced decay and extensive loss of its exterior mural decoration. In these circumstances, among the problems raised by the conservation treatment, the aesthetical presentation became a challenge for the conservators. A minimalist approach was chosen for the treatment of the support lacunas using coloured and texturised fillings, in order to valorise the original painting fragments.
Introduction The conservation project for the exterior mural decoration of Coltea Church1 required a particular approach due to the fact that the condition of the monument is the result of many previous interventions, some owing to significant historic circumstances. Among the interventions that aimed to 'restore' the monument, there are some that have acquired historic value of their own, such as the interior oil paintings executed in 1871 to replace the original frescoes which had been previously removed. This major intervention was the result of a change of taste that became fashion in the second half of the 19th century and that introduced a new artistic manner under the influence of the Western art: the neoclassicism. Oil painting was a novelty in Romania, particularly in churches, appearing colourful and brilliant when compared to the traditional Byzantine frescoes. From this reason it was used as decoration technique not only for new monuments but also to replace the already existing frescoes in churches. At Coltea, the repainting executed by Gheorghe Tattarescu2 was limited to the interior walls of the church. This oil painting induced a heterogeneous aspect of the overall ensemble, although today we must regard it as a fait accompli and acknowledge its own historic value. Only a small part of the original 17th century painting attributed to Parvu Mutu3 was preserved in the porch of the church, the exterior murals decoration and a frieze in the lower part of the original steeple, recently discovered during the rehabilitation works. As the monument presented several historic interventions from different time periods, a difference had to be made between those that are significant to its identity. Thus, the ultimate objective of our intervention was to correct and regain the authentic configuration and artistic image of the church. Monument description The actual Coltea church was erected around 17004 by Mihai Cantacuzino and it was built over the foundation of an old wooden church. The new edifice was built in masonry, and it gradually developed into a monastery, a complex ensemble that included a hospital, a school, a chapel and several other annexes. The highest bell tower in Wallachia was erected at the entrance of the surrounding wall. Unfortunately the 1802 earthquake seriously affected Coltea ensemble: the tower suffered serious damage and was demolished in 1888 due to the systematisation of the urban area. In the same period the hospital was completely rebuilt. The church steeples, irrecoverably affected by the earthquake were also demolished, one of them being rebuilt in a later rehabilitation project. From the original ensemble of Coltea monastery only the church has survived until the present. The church was built on a triconch plan, with a slightly widened narthex and an open porch with arches supported by columns. The church, measuring 27.50 m long, 11.95 m width (on the apses) and 10 m height, seems rather small today when compared with the buildings that surround it, although at the time of its construction it was one of the most important medium-sized churches in Bucharest. Exterior mural decoration Coltea church is a monument with well balanced volume and beautiful proportions, emphasized by the configuration of the facades. These are separated into two registers through a rope shaped plaster frieze. Recent surveys have uncovered a dentate frieze made of bricks below the first one. The horizontal registers are divided in several niches that vary in shape and size. The superior register is decorated with arched niches and the inferior one with three overlapping rows of accolade-shaped niches. The facades are decorated with ornaments executed in a fresco technique. A basic chromatic scale was used with red, ochre and black colours on ochre background. The decoration depicts repetitive vegetal and geometric motifs. The largest preserved area of mural painting is in the superior register of the south facade while the rest was covered with plaster repairs and layers of repainting from different periods. The north facade was entirely replastered, thus all its mural decoration is lost. Following stratigraphic surveys it was found that many of the repairs were in poor condition, the plaster was friable or macerated and part of the niches profiles was damaged at the time of our intervention. Conservation state and degradation causes Aging factors caused by the characteristic local climatic conditions, calamities such as damages occured during the Second World War and successive earthquakes have caused significant degradation of the monument over time. Among other destructive factors, the inadequate repairs with cement content, the elevation of the ground level around the church, large areas of concrete and asphalt in the vicinity and inadequate sewerage and drainage systems led to the increase of moisture in the walls. Humidity, by both infiltration and capillarity, is responsible for the loss and decohesion of the support and paint layers, as well as for the pulverulence and detachment of the colour. At the moment, even if the ground level was lowered back to the initial level (80 cm above the 1.50 m foundation) the walls moisture problem has still not been resolved. Situated on one of the main thoroughfares in the centre of Bucharest, Coltea church is also subject to degradation due to several atmospheric pollution sources. Prior to our intervention, black areas could be seen on the facades due to the presence of calcium sulfate dihydrate (gypsum, CaSO4.2H2O). X-ray diffraction has shown that its presence was due to the sulfating process resulted from the reaction with the sulfur dioxide (SO2) present in the atmosphere. Contrasting, light areas could be seen on the surface due to exposure to acid rain (sulfur and nitrogen acidic compounds). The painting of the northern facade was the one more affected by the rain, which falls directly onto the wall. The high level of moisture favoured the appearance of biologic attack on the mural surface, both on the south and north facades. According to the analysis made by the National Research Institute for Conservation and Restoration of Cultural Heritage, fungal species such as Penicillium, Mucor and Acremonium were present on the painting. Furthermore, due to their exterior location, the paintings are subjected to severe climate changes: a very high temperature and relative humidity during the summer (maximum 52°C and 90% RH) and low levels during the winter (maximum -20°C), these having lead to changes in the structure of the constituent material and at the same time to the alteration of the pigments quality. Even if generally we may state that the conservation state of the constituent materials was relatively stable, the overall state of the monument was poor, the masonry presenting degradation such as profound cracks in the axis of the chancel and of the two apses. Numerous cracks appeared in the domes and correspondent arches and extended on the south and north walls and superficial cracks were visible on the entire upper surface of the facades. The profound walls cracks induced serious structure problems to the church. In order to solve this problem, a consolidation project started in 2000. Previously to this project, the painted surface was secured by the conservators in an emergency intervention in order to avoid its further degradation during the works. However, the consolidation intervention worsened the state of the paintings leaving consolidation material leakages and drops on the surface. In the course of time, several other conservation attempts were made (as a consequence of the damages occurred during the 1808, 1838 and 1940 earthquakes) but even if they succeeded to temporarily rehabilitate the monument, most of them proved to be incorrectly executed, having generated a further chain of degradation at the support and consequently the paint layer level. Moreover, these several interventions and repairs resulted in the inherent change of the ensemble configuration. The most evident alteration was caused by a very recent rehabilitation project that included the reconstruction of the two steeples of the church. Today, one can see a historic ensemble restored by parts and based on different aesthetic principles. Indeed, there is a disturbing difference between the rebuilt surface and the conserved one. At the time of our intervention, a special situation was encountered with the north facade, whose entire surface had been practically rebuilt of plaster based on lime and sand. In the moment of our intervention, its advanced state of deterioration did not allow its preservation on certain areas, even if properly consolidated. In these conditions, the removal of friable and macerated parts up to the masonry was required. All the above mentioned forms of degradation required the implementation of a work methodology that could resolve the entire existent problems of the ensemble. Technological exam The masonry The masonry is made of good quality well-fired bricks measuring cca. 3.5 x 28 x 14 cm. These are bound together by mortar made of coarse river sand and lime, applied in layers of almost the same thickness as the bricks. The walls have a thickness of 1.25 - 1.40 m and consist of double lines of bricks placed alternately along their length. The support layer The support layer is made of lime and sand mortar. The previous fillings and repairs were generally made with compatible mortars but also with lime, cement, gypsum and whitewash along the cracks and fissures. The laboratory tests of mortars used in the repairs showed that they have different hardness grades, some being very friable while others are compact and of an average hardness. The binder/ aggregate ratio ranges from 1/9-1/3. The mortar sand grain is between 0.1-2mm, with a preponderance of 200–630 µm. The paint layer The painting was done onto a fresh plaster made of lime, sand and tow. The pigments identified by chemical analyses are iron oxides (red and yellow-ochre), smalt blue and carbon black. Intervention Methodology The conservation-restoration treatment followed the methodology established by us and previously approved by the Romanian Ministry of Culture. The methodological steps were determined after carrying our preliminary tests on the entire intervention area in order to establish the particularities of the surface and to define the appropriate operations to be executed, as well as the substances, solutions and materials to be used in this process. Tests were particularly important to determine the effectiveness of various treatment procedures in respect to the response of the painting and to achieve a preliminary impression of the results. Tests included stratigraphic surveys of the area to establish the extent of original painting under the previous fillings and cleaning tests for the consolidants traces, lime drops and other deposits present on the surface. At the same time laboratory exams were carried out for the support and paint layer as well as for the materials used in the previous interventions, in order to establish very clearly their nature and to be able to ascertain the treatment for the entire surface. After the removal of the previous repairs, the methodology intervention was revaluated in respect to the uncovered surface and its actual conservation state. It was seen that the losses at the support layer level were extensive and the only possible approach that would permit the valorisation of the original painting fragments was to adopt a minimalist approach for the aesthetic treatment. Interventions at the support level The first task to complete was to remove the incorrect repairs from the previous interventions or the fillings done with mortar that lost its cohesion. These were executed with several types of materials (such as lime and sand, sometimes with addition of tow, or lime, sand and cement) and often exceed the areas of the lacunas, overlapping the painting surface. Due to the poor condition of the mortar, this had to be removed until the masonry in some areas. The immediate step was the biological treatment of the surface. A solution of Desogen (3%) was applied by brushing or spraying through Japanese paper. The areas affected by biological attack were monitored during the entire intervention. It was then proceeded to the consolidation of the friable areas of the support layer with a solution of Syton X30 (5%). The operation was performed by repeated brushing or spraying the solution at time intervals until the expected results were achieved. Once the support was stabilised, we could proceeded to the filling of the cracks and deep lacunas of the support. A coarse mortar was applied in several layers so that it would evenly remain cca. 5 mm below the level of the paint layer. This surface difference allowed the ulterior application of a finer mortar layer. After filling the lacunas, the consolidation of the detached areas of the support by injection was performed, using Ledan 1/1 in distilled water. The very fine cracks that could represent outlets for the injected consolidant were temporarily secured by the application of pelure paper strips with purified Carboxymethyl cellulose. Cleaning and consolidation of the colour layer Surface cleaning aimed at the removal of the dirt deposits but also of the overpainting layers. It was perform by alternation of dry and wet means (wishab sponges, erasers, fibreglass sticks, scalpels) until the expected result was obtained. The application of patches with ammonium carbonate (5%) was necessary in some areas to soften the hard deposits present on the surface, such as cement, lime drops and leakages from the previous consolidation works. The removal of overpaintings was preceded by tests to establish their resistance to solvents and the response of the original surface. As they were done a secco, with pigments and a weak organic binder, the removal was possible by softening the areas with ammonium carbonate (5%) patches left in contact with the surface for about 5 minutes, followed by the mechanical removal of the layers. Cotton swabs were further used in order to eliminate any traces from the painting. The consolidation of the surface was done by treatment with ammonium oxalate5 . This pH neutral product was chosen as an alternative for the treatment with barium hydroxide. Poultices with paper pulp and ammonium oxalate solution in distillate water (5%) were applied for 4 to 6 hours at a temperature between 18 and 24° C, so that the transformation of calcite in calcium oxalate can be achieved. Due to the fact that the conservation project took place during the summer, and the day temperatures were between 32 and 40° C, the treatment with ammonium oxalate took place during the night. This treatment is laborious and requires attention to other factors involved, such as the protection of the surrounding surface on an area of 2-3 cm by the application of distillate water patches in order to prevent the migration of the ammonium oxalate. This treatment achieved the reduction of the porous surface absorption coefficient and the enhancement of the cohesion and thus, the protection against atmospheric pollutants. Aesthetical presentation The aesthetic treatment of the paint layer was done according to the minimal intervention principle, a decision required by the painting condition itself. Limiting the chromatic reintegration of the colour to minimum we could value the original painting fragments and preserve the authentic aspect of the surface. Thus, the losses of the support were filled with coloured mortars under the level of the paint layer while only a subtle reintegration was done in areas where the colour layer was lost. A neutral tone was used to naturally shade away the visually disturbing elements such as the considerable erosions of the plaster. The small colour losses on the painted ornament were punctually integrated by velatura and ritocco. Filling the support losses Aesthetic presentation of the areas with extended support losses using coloured, texturised fillings was made on the entire north facade, partially on the eastern facade and in the inferior register of the south facade. Mortar made of lime and stone powder was selectively coloured with pigments in order to achieve a neutral but closer tone to that of the original. The operation was carried out by applying mortar in the superficial lacunas of the support or those large lacunas previously filled, followed by the application of a porous and uneven texture to the fillings. Mortars composition was established as a result of a series of tests and it differ from an area to another, depending on the local tone of the original painting. In the composition of lime stone mortar various amounts of pigments were added (blue and iron oxides: black and ochre) in order to obtain areas with a chromatic quality that closely resemble to the original but remain neutral at the same time, recognisable from the original also through their texture and level. The composition of mortar contained one part of hydrated lime and one part of fine stone powder and was pigmented depending on the application area, as shown in Table 1. The chromatic reintegration of the colour layer As previously mentioned, our intervention was minimal and sufficient to balance the chromatic harmony of the surface and also to allow a good perception of the original painting. Thus, the various damages of the colour layer were treated selectively as follows: - for the chromatic integration of the erosions it was sought to apply a diluted watercolour glaze matching the quality and accumulation level of the surface patina. At this level, the losses were superficial and were visible only as a slight abrasion affecting the continuity of the paint layer. Our intervention reestablished the continuity of the area without changing the colour and tone of the paint layer. - for the chromatic integration of the lacunas in the pictorial field neutral tones close to the local colour were applied that would easily differentiate our intervention from the original. The methods used were velatura and ritocco. In a final stage a fixative was applied to protect the chromatic integration (Acryl 33, 3%). Conclusions By using coloured mortars applied below the level of the support layer the chromatic unity was achieved and at the same time, the authenticity of the mural ensemble was preserved. This type of intervention was also sought to easily differentiate between the fully reconstructed areas (towers, cornice, northern facade and inferior areas) and those few areas that preserved original decoration. Acknowledgements The authors would like to thank conservators Anca Nicolaescu, Nicoleta Pascale, Mihail Mihalceanu and Mihaela Topor without whom the successful outcome of this project would not have been possible to achieve and to all other professionals whose contribution and advice has been much appreciated. The participation of conservation students from the National Art University, willing to accumulate more experience and knowledge on this worksite, has been most welcomed. Our thanks are extended to CONTEAM constructors team led by Dipl. Ing. Alexandru Georgescu as well as to the contractor company AST Romania, particularly to Mr. Michael Kratzer and Mr. Mircea Cvaci for their consideration and permanent support.
Photo credits
Figure 2. Photo by Elena Martin, 2001. Figures 5, 6. Photos by Raluca Biltiu Ceicu in 1989. Figures 7-10. Photos by Teodora Poiata and Andreea Banea-Grimm in 2001 during the conservation of the porch. All other photos by Simona Patrascu, Anca Nicolaescu and Teodora Poiata during the conservation project in 2006.
Notes:
1. The project took place in 2006 and was coordinated by Simona Patrascu, Restauro Art Grup S.R.L.
2. Gheorghe Tattarescu, one of the first neoclassicist artists from Romania, decorated several churches in this manner. 3. Parvu Mutu (1657-1735) (eng. Parvu the Mute) was a Walla-chian painter, famous for his portraying manner and for decorating in a fresco several Romanian church-monuments.
4. The exact date is not known, but by some literature sources, it was between the years 1695 and 1698, while other mention the period between 1700 and 1701.
5. M. Matteini, and S. Giovannoni proposed the use of ammo-nium oxalate to produce a superficial layer of calcium oxalate on limestone substrates such as wall paintings. Carbonated calcium and calcium sulphate react to treatment by poultice with ammonium oxalate solution to recover the cohesive-ness of the surface, leaving unaltered the optical and hydro-philic properties of the material. Matteini, M. and Giovannoni, S. 1996. "The Protective effect of ammonium oxalate treat-ment on the surface of wall paintings". In: Painted Facades. Proceedings of the Eurocare Project, Vienna 1996, pp. 95 - 101.
About the authors
Simona Patrascu
Contact: simona_kp30@yahoo.com
Simona Patrascu is a conservator of mural paintings and one of the co-founders of Restauro Art Group S.R.L. conservation enterprise. She specialised in 1995 in the conservation of Ceramics, Glass and Metal, at Spiru Haret University, in Bucharest and in 1998 she received the degree in mural paintings conservation from the National Art University in Bucharest. Since 2000 she is member of the conservation section and professional commission of the Romanian Artists Union. While at Restauro Art Grup, she coordinated several conservation projects of church monuments from Romania.
Teodora Poiata
Contact: teodora.poiata@e-conservationline.com
Teodora Poiata is a paintings conservator and has extensive experience with mural paintings, in particular with Byzantine frescoes. She received her BA degree in conservation from the National Art University in Bucharest in 2002 and the MA degree in 2005. Her interests include documentation methods and open access to information in conservation, which motivated her to co-found e-conservation magazine where she is editor since 2007. At present she divides her time between Romania and Portugal where she works in on-site mural paintings conservation projects.
About Restauro Art Grup
Anca Nicolaescu and Simona Patrascu, together with the expert restorer Silviu Petrescu, founded Restauro Art Grup S.R.L. in 2000, a conservation enterprise accredited by the Romanian Ministry of Culture. The enterprise had run several conservation projects for important historic monuments in Romania, among which the conservation of the mural ensemble from the Surpatele Monastery (2002-2003), the a fresco mural painting conservation from the Church of Jgheaburi Monastery (2003-2004), the conservation of the exterior a fresco murals and architectural renderings from Coltea Church (2006) and Mantuleasa Church (from 2007 up to present).
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