The UGR participates in a European project to prevent damages provoked by salts in historical buildings

However, despite the last achievements in the field of restoration, up to now they have failed to design effective measures to fight against this problem. In order to prevent the damage caused by sulphates, chlorides and nitrates in buildings and their progressive erosion scientists of the University of Granada, in collaboration with the Instituto Andaluz de Patrimonio Histórico (Junta de Andalucía), the University of Münster (Germany), of Ghent (Belgium), the University College of London, the University of Patras in Greece, the Technical University of Prague, the Architectural Preservation Centre of the Netherlands and the Technical University of Eindhoven, have put into practice a research project to analyse not just the appropriate inhibitors to avoid salt but also to use their achievements in the Monastery of Saint Jerome, one of the most damaged buildings for this reason of Granada, and in a medieval castle in the outskirts of Prague.

The project, which has been financed by the 4th Framework Programme with a budget of 1,000,000 euros, started last January with the development of the first inhibitors in the laboratory. Throughout the last twelve months the scientists have achieved their first results and, although it is still too soon to expound conclusions they can assert that “this method will be very effective in salt treatment”. The coordinator of the project in Spain and professor of the UGR [http://www.ugr.es], Carlos Rodríguez Navarro, points out that the first thing they have studied is salt crystallization dynamics and kinetics (thanks to the electron microscopy technique of environmental scanning) to determine the best inhibitors in the treatment of the ornamental materials and explains that “the experiments have been carried out with sodium chloride, sodium sulphate and magnesium sulphate, which are the salts that more affect at present Granada’s heritage and up to know we have managed to apply effective additives in low concentration that, besides being very effective in the fight against these alteration problems, are quite cheap”.

Experiments with limestone

Although the first data extracted in the laboratory are more than promising, they still can not be used on the heritage as they must be completely sure of their effects and be very cautious to avoid damaging an insurmountable wealth. In order to avoid this, the next step of the research work will be to put to the test the inhibitors through multiple experiments simulating identical or very similar conditions to those of the building. In order to use this method in the Monastery of Saint Jerome they are carrying out experiments with limestone extracted from the same quarries that supplied the construction of this building. These first tests will also be useful in future to apply this system in other buildings of the city such as the Cathedral or the Chancery although, according to the scientist, “there is not an only recipe”, and therefore, every time they work on a monument they will have to study its characteristics in order to use the appropriate inhibitors and not to damage the stone”.

Once they conclude laboratory tests, they will start the intervention in the Monastery of Saint Jerome, first in a small pilot area to observe how the system works and afterwards along the building, one of the most affected by this problem: ”Dampness, pollution deposits or antisocial behaviours are the main causes for the appearance of salts in this building and the effects provoked by them such as the loosening of some pictorial layers, material loss, sand and dust accumulation in the low areas and severe damage in sculptural heritage”, says the professor of the department of Mineralogy and Petrology.

Up to now the treatments used to fight against the erosion of the building “had work as a simple make-up”, and therefore the objective of the research work “is to avoid prevent salt from crystallizing inside the stone, getting it to emerge to the surface of the material in such a way as it can be cleaned with a brush without causing any damage”.

The project, which has to be finished at the end of the next year, is integrated in the specific research projects of the 4th Framework Programme and has already managed to publish the previous data in the Journal of Crystal Growth, one of the most prestigious scientific journals in this field.