Contact angle analysis of biocolonized stone surfaces: Comparative study of benchtop and portable approaches to advance on-site applications

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.