1st One-day symposium of the Center for the Study of Cultural Assets
Battling to save historical buildings and cultural treasures
Historically important buildings and valuable cultural assets are always at the mercy of the their environment, both outside and indoors. Often specific measures are required to afford them adequate protection against the damaging effects of the prevailing biological and chemical conditions. Experts from the fields of the natural sciences, conservation and restoration of old buildings and antiquities, and education met recently at EMPA to discuss this topic and exchange experiences.
«Falcon hunt» in the former chapter hall of the
evangelical-lutheran collegiate church of St. Alexander,
Wildeshausen (Photo: Tobias Trapp, Oldenburg)
| The symposium on November 27th 2003 was the first organized by EMPA’s Center for the Study of Cultural Assets, and provided professionals in this field with a meeting point and a platform for the exchange of ideas. Presentations were given on topics such as the effects of humidity and temperature variations on historical buildings and architectural assets, one consequence of which is microbial attack. Steps to treat and prevent such attacks were discussed, as were the analytical chemistry studies, which are a fundamental requirement for the development of proper restorative measures. | ||||
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Many different kinds of damage and ways of restoration The problems of religiously significant monuments from the viewpoint of building physics were detailed by Roland Büchli, EMPA’s expert on building damage. Churches and chapels are not used continuously, as are houses and commercial buildings, but often only occupied – and heated – once or at most a few times per week for religious services. This cycle of varying indoor air conditions results in problems such as condensation and fungal attack, which is of course detrimental to the plastering on internal walls and works of art in the building. In his lecture, Mr. Büchli demonstrated the significance of correctly evaluating the damage from the building physics’ aspect in order to ensure than further deterioration can be prevented. |
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| Specialists from the Expert Center Lausanne next reported on the newly begun restoration of the cathedral in that city. The façade, which dates from the 13th century, was fully renovated in the 19th century, but some of the materials then used are already in need of replacement. This project demonstrates the difficulty of reconciling the sometimes-conflicting requirements of building construction and conservation. | ||||
| Excess dampness encourages microbial growth EMPA’s Dr. Paul Raschle then spoke about microbial analysis, one element of scientific investigation which offers help in tackling the problem of microbial damage in a sustainable manner. The cause of fungal and microbial growth always lies in excessive humidity. A case in point is fungal attack suffered by the paintings in the church of the cloister in Mustair. Investigation revealed that varnish applied during the last restoration was providing nourishment for the fungus and thereby helping to destroy the works of art. The source of the humidity, which was encouraging the growth, was not the building walls but the room air, so the fungal attack was stopped by the twin measures of removing the varnish from the paintings and dehumidifying the room air. |
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| Slowing down the rate of deterioration Conservation measures to counter weathering was the topic discussed by Dr. Christiane Bläuer Böhm of the Expert Center for Historic Monuments, Zurich. Since the effects of weathering and aging cannot be fully avoided, and are irreversible, efforts are concentrated on slowing down the rate of deterioration of listed buildings. To achieve this end steps are taken to modify environmental factors or material properties appropriately. |
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Laser light for analysis and renovation The discovery that laser light could be used not just for studying works of art but also removing surface layers was made shortly after the development of the first laser in the 1960’s, as Jens Hildenhagen of the Laser Center of the Technical University, Munster, Germany, informed the audience. Soon thereafter a ruby laser was used to remove the weathered surface crust from a marble artifact. The development of more powerful lasers meant that by the 1980’s they had become practical tools for cleaning works of art. |
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| In particular, the laser method’s ideal characteristics – noncontact operation, fine power control and limited local effect on the object being treated are – enable very precise cleaning to be carried out. However not all materials are suitable for treatment by this technique, since with very delicate objects there is the danger of removing too much material. Today, however, there is a wide range of different types of lasers and cleaning systems available from which to choose the most suitable for a particular application. | ||||
| Enzymes help to remove casein coatings Many significant works of art have been rediscovered since the middle of the 19th century through the uncovering, preservation and restoration of historic mural paintings. Sometimes, to preserve these works, newly developed products have been used in addition to traditional renovation materials. Little is known about the long-term characteristics of these new products. One particular problem exists when a casein layer has been applied in the past to stabilize a mural. The resulting damage can lead to the loss of the entire work of art, and to date it has not been possible to remove casein coatings without considerable damage to the original materials. Kerstin Klein of the State Ministry of Memorials and Monuments, Hanover, reported on a current project, involving partners from industry and science, to develop a method of using enzymes to remove caseinate from wall murals in a careful, controlled manner. The first step was to develop a non-destructive method of identifying the presence of casein on a work of art. Then an enzyme suitable for breaking down the caseinate had to be found. Preventing the transfer of microorganisms onto the priceless murals was also a challenge that had to be overcome. One important advantage the enzyme technique is that it poses no health problems whatsoever to those using it, since the enzymes are non-toxic. |
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| Analytical techniques are not wonder-cures! EMPA offers a comprehensive range of analytical techniques, which were presented in the last lecture of the symposium by Dr. Axel Ritter. Each and every work of art requires individual evaluation and treatment, since the samples under study are often unique and irreplaceable. Knowledge of the materials used to make the object provides a better understanding of the civilization which created it. The availability of countless analytical techniques might give the impression that all the problems involved can be magically cured, but the interpretation of the results is as important as the results themselves. For this difficult, time-consuming but critical step in the process, EMPA works in collaboration with specialists in the humanities and earth sciences. |
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In the general discussion, which ensued at the end of the formal proceedings, several speakers expressed views encouraging the renovation of church buildings. An essential condition to allowing public access to renovated churches as museums was, however, a stable indoor microclimate to prevent damage to works of art. On this point, it was agreed, there was no generally applicable single solution. |
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Center for the Study of Cultural Assets Contact person: Marianne Senn |
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