Contact angle analysis of biocolonized stone surfaces: Comparative study of benchtop and portable approaches to advance on-site applications
Letizia Berti,
Davide Gulotta,
Federica Villa,
Lucia Toniolo,
Gabriele Gianini,
Francesca Cappitelli,
Sara Goidanich
Affiliations
Letizia Berti
Department of Sciences of Antiquity, “La Sapienza” University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; Department of Chemistry, Material and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milan, Italy; Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Via Luigi Mangiagalli 25, 20133 Milan, Italy
Davide Gulotta
Getty Conservation Institute, Science Department, 1200 Getty Center Drive, Los Angeles, CA 90049, USA; Corresponding author
Federica Villa
Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Via Luigi Mangiagalli 25, 20133 Milan, Italy
Lucia Toniolo
Department of Chemistry, Material and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milan, Italy
Gabriele Gianini
Department of Informatics, Systems and Communication, Università degli Studi di Milan-Bicocca, Viale Sarca 336, 20126 Milan, Italy
Francesca Cappitelli
Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Via Luigi Mangiagalli 25, 20133 Milan, Italy
Sara Goidanich
Department of Chemistry, Material and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milan, Italy
Summary: While traditionally confined to laboratory settings, recent developments have enabled Water Contact Angle (WCA) measurements to be conducted on-site, under field conditions. This study presents a comparative evaluation of a conventional benchtop method and a portable instrument applied to uncolonized and biocolonized stone surfaces. A reference non-absorbing substrate was used for method validation. Results showed good agreement between the two methods on non-absorbing surfaces, confirming the reliability of the portable approach. On porous biocolonized substrates, the methods differed in absolute WCA values but showed consistent trends, while there was good agreement among drop absorption times. These findings demonstrated that the portable approach can effectively capture water-related properties on-site, with minimal invasiveness and high reproducibility. The study introduces a validated and statistically supported methodology for on-site wettability and water absorption assessment and emphasizes the influence of biofilm composition on surface water-related properties, contributing to the broader understanding of SAB-induced surface modification.
