Holistic Approach to Cleaning and Protection of Stone Façades of 20th Century Architectural Heritage

Abstract

Modern urban areas represent our recent past with great aesthetic and heritage value which should be maintained and preserved for the future. One of the best recognized landmarks of the city of Novi Sad, capital of Vojvodina region positioned in northern Serbia, is the architectural masterpiece Banovina Palace in which today resides provincial government. It is an elongated, closed, horseshoe-shaped structure, built in late 1930s in a modern style and influenced by expressionist architecture. Two-floor high with a tower on one end the building dominates the scenery and symbolizes the appearance of a large ship on the Danube River which flows in the immediate vicinity. The façade of this famous building is covered with white marble from Adriatic island of Brac. After almost 80 years of exposure to weathering, urban pollution and manmade devastation, the façade was in need of cleaning, consolidation and protection. In the attempt to prepare for the European Capital of Culture 2021, the City of Novi Sad started ambitious project of local heritage revival. Due to awareness of lack of understanding about stone nature and behaviour, stone cleaning and protection usually raises concerns and cautious. The Laboratory for Materials in Cultural Heritage, Faculty of Technology, was invited to join the project to preform holistic characterisation of the stone, reveal deterioration mechanisms, and propose conservation methodology. Using mobile laboratory with non-destructive techniques coupled with laboratory testing, the stone façade was comprehensively analysed. Various deterioration patterns were identified including patina, dirt deposits, eroding surfaces, yellow layers and black crusts, large amounts of carbonaceous particles responsible for black appearance of stone surface, soluble salts, microbiological corrosion, residue of inadequate graffiti removal, façade paints, acrylic binders, as well as mechanical damage of stone panels. Based on laboratory testing of a number of cleaning, consolidation and protection techniques and products, the most promising ones were also tested in situ [1]. Products ranging from traditional conservation approaches to innovative solutions like self-cleaning photocatalytic coating as final protective layer, were selected [2]. Resulting from research the methodology for cleaning, consolidation and protection was established in 2017 and implemented in 2019, where the laboratory acted again as scientific supervision and control of the conservation works. The presented approach allowed deep understanding of the complex problem and guaranteed responsible conservation strategy; therefore it stands as an example of 20th century architectural heritage preservation.

Full document

References

[1] Moura, A., Flores-Colen, I., Brito, J. and Dionisio, A. Study of the cleaning effectiveness of limestone and lime-based mortar substrates protected with anti-graffiti products. J. Cult. Herit. (2017) 24:31-44

[2] Pondelak, A., Kramar, S., Ranogajec, J., Škrlep, L., Vucetic, S., Ducman, V. and Sever Škapin, A. Efficiency of Novel Photocatalytic Coating and Consolidants for Protection of Valuable Mineral Substrates. Materials (2019) 12:1-15

[3] Mercedes Perez-Monserrat, E., Fort, R. and Jose Varas-Muriel, M. Monitoring façade soiling as a maintenance strategy for the sensitive built heritage. Int. J. Archit. Herit. (2018) 12:816-827

[4] Webster R. Stone Cleaning and the Nature, Soiling and Decay Mechanisms of Stone. Donhead London, (1992)

[5] Elena Charola, A. Salts in the Deterioration of Porous Materials: An Overview. J. Am. Inst. Conservat. (2000) 39:327-343

[6] Camuffo, D., Del Monte, M., Sabbioni, C. and Vittori. C. Wetting, deterioration and visual features of stone surfaces in an urban area. Atmos. Environ. (1982) 16(9):2253–59

[7] Lamhasni T. et al. Air pollution impact on architectural heritage of Morocco: Combination of synchronous fluorescence and ATR-FTIR spectroscopies for the analyses of black crusts deposits. Chemosphere (2019) 225:517-523

[8] Catarina Pinheiro, A., Limestone biodeterioration: A review on the Portuguese cultural heritage scenario. J. Cult. Herit. (2019) 36:275-285

[9] Senesi, G., Allegretta, I., Porfido, C., De Pascale, O. and Terzano, R. Application of micro X-ray fluorescence and micro computed tomography to the study of laser cleaning efficiency on limestone monuments covered by black crusts. Talanta (2018) 178:419-425

[10] Carvalhão, M., and Dionísio, A. Evaluation of mechanical soft-abrasive blasting and chemical cleaning methods on alkyd-paint graffiti made on calcareous stones. J. Cult. Herit. (2015) 16:579-590

[11] Rodrigues, J.D. and Grossi, A. Indicators and ratings for compatibility assessment of conservation actions. J. Cult. Herit. (2007) 8:32-43

[12] Project “Protection of Cultural Heritage Objects with Multifunctional Advanced Materials” - HEROMAT, granted by the European Commission in the Seventh Framework Programme (2007—2013), Grand agreement No. 282992. Available online: www.heromat.com (accessed on 18 February 2020)

[13] Vučetić, S., Rudić, O., Markov, S., Bera, O., Vidaković, A., Sever Skapin, A., Ranogajec, J. Antifungal efficiency assessment of the TiO2 coating on façade paints. Environ. Sci. Pollut. Res. Int. (2014) 21:11228–11237