Saving Europe's cultural heritage
One of the oldest organs in Poland sits in the Minor Basilica of St. Andrew, about 60 kilometres east of Cracow. It has been in use since 1611. Not much written documentation from this time has survived, leaving the organ as a rare link to the true sounds of the Renaissance and Baroque periods. However, like many artefacts of cultural heritage, its age is beginning to show. The need for preservation has prompted many European scientists to action.
Physicist Lukasz Bratasz visits the organ on a monthly basis. He uses special sensors to monitor the micro-acoustic emissions from the cracks in the wooden structure. The inside of the organ is very sensitive to changes in its environment, be it climatic, biological, chemical or physical. During a service in winter, it is not unlikely for the temperature to rise from zero to twenty degrees, due to human activity. Lukasz is of the opinion that this particular organ is in quite good condition, but requires continued monitoring.
The Polish Academy of Sciences' Institute of Catalysis and Surface Chemistry is where the data from Lukasz Bratasz is analysed. The institute is a partner in the EU's 'Sensorgan' project, researching the effects of indoor environments on Europe's tens of thousands of organs. They investigate, among other things, how the wood reacts to sudden temperature and humidity changes. Laser mapping is used here to examine cracks at an impressive scale.
Research has shown how the most dangerous environmental changes are those that occur very quickly, for example, by the use of an air-conditioning system. However, drastic changes in temperature and humidity are at their most threatening when the material is exposed openly to interact with the environment.
Telč, in the Czech Republic, is a medieval town whose historic centre is included in UNESCO's World Heritage List. The 53-metre high church of St. James shows signs of the stress and fatigue, accumulated over the last five centuries. Two large pieces of stone have already broken off and more cracks are starting to appear. Jiří Blaha, a civil engineer, explains that the iron railings and the massive but porous stones are joined together in an impractical manner, where the joints are exposed to wind, rain, snow and large changes in temperature. The iron rusts, increasing in volume and, in turn, cracking the stone.
Jiří and his colleagues have taken part in 'Noah's Ark', an EU-funded project considering the medium and long term effects of global climate change on European cultural heritage. Their predictions are not particularly uplifting: rain will continually leak into the porous stones, while increases in humidity allow for the spread of fungi and bacteria over building fronts and roofs, as well as the formation of salts, which degrade surfaces and influence corrosion.
At the Institute of Theoretical and Applied Mechanics in Prague, wooden models are being used to test a building's resistance to heavy wind and rain. The institute's researchers are also testing the sturdiness of stone types from historical buildings. Two large ornaments, removed from a 14th century church in Bohemia for safety reasons, are now being used to test water absorption and how humidity and water causes damage.
The key to success in such research is to develop improved preventative measures. While restorations are underway at many sites, including the Prague Castle, experts remind us of the value of authenticity, letting the sites of cultural heritage grow old without reworking them. Whether it's a cathedral or the organ inside it, monitoring and prevention must come before restoration. Our common cultural heritage is a non-renewable resource to be transmitted to future generations and the development of preventative strategies based on early and cost-effective action is an urgent priority in an area where Europe has leads the world.