Ferrol, 29th April 2024.- The accumulation of polluting particles on the surfaces of historic buildings and monuments represents a challenge for the conservation of cultural heritage. Known as ‘black crusts’, the ones we are talking about do not only affect the aesthetics of the structures, but also compromise their integrity and durability.
A DOCTORAL THESIS ADDRESSES THE PROBLEM OF ENVIRONMENTAL POLLUTION ON THE PRAGUE WATERSHORES
This problem is especially evident in Prague’s iconic bridges, whose architectural grandeur and historical significance make them prominent victims of environmental pollution caused by the use of fossil fuels in vehicles and heating systems, among other factors.
A scientific team from Charles University (CUNI) in Prague, expert in geology, is tackling a triple challenge: to characterise these deposits, to analyse how their composition affects the granite used in the construction of the bridges and to test the effectiveness of the laser technique for their cleaning.
Vendula Natherová, a predoctoral student at the Institute of Geochemistry, Mineralogy and Mineral Resources of the Czech institution, is part of the team. The thesis, directed by researcher Richard Přikryl and titled ‘Influence of postgenetic alteration processes on mineralogical composition and rock fabric of granitoids in relation to their physical/mechanical properties and durability’, focuses on the study of these contaminating deposits, with the aim of assessing their impact on granite deposits in order to establish suitable measures for future restoration processes.
ADVANCED TECHNIQUES REVEAL THE COMPOSITION OF THE CRUSTS
Vendula is currently doing research at CITENI’s Laboratory of Industrial Laser Applications thanks to the Erasmus+ KA131 SMT programme for the mobility of trainees. Ana Xesús López, Alicia Moreno and Alberto Ramil, expert researchers in laser technology applied to built heritage, collaborate in the project, together with the researcher David M. Freire Lista, from the University of Trás-os-Montes e Alto Douro (UTAD). The team worked with samples of black strass taken from the František Palacký Bridge, the third oldest bridge in Prague, built in 1876.
Advanced techniques such as Raman spectroscopy, X-ray fluorescence and scanning electron microscopy were used to characterise the composition and morphology of the strands. The results obtained so far reveal that it is an anthropoxenic layer (a product of human activity) very rich in carbon and xofre (substances from fossil fuel combustion in vehicles or boilers). Cleaning tests were also carried out with different laser equipment with very satisfactory results and hardly any effect on the granite.
PRESENCE AT INTERNATIONAL CONGRESSES ON HERITAGE CONSERVATION
The advances of this research will be presented at two important international congresses dedicated to heritage: the 7th International Congress Chemistry for Cultural Heritage 2024 (CHEMCH 2024), to be held in July in Bratislava; and the V International Congress Technoheritage 2024, to be held in September in Santiago de Compostela.
Tackling the problem of environmental pollution, in this case on the iconic Prague bridges, is not only a matter of preserving cultural heritage, but also a call for attention to the quality of the air we breathe and the need to take measures to protect our health and the urban environment.
In addition, the new European environmental guidelines, which promote the reduction of fossil fuel consumption and the use of green technologies, such as those based on lasers, offer a unique opportunity to carry out conservation and cleaning interventions on historic monuments, such as the Prague bridges, in an effective, minimally invasive and environmentally friendly way.
