Assessing surface weathering by revision and implementation of the peeling-test: in situ sampling and integrated analyses

Weathering diagnostics is mainly focused on the characterization of deterioration patterns in a mostly descriptive and non-quantitative way. Several authors tried to numerically evaluate rate and extent of the decay features highlighted in case studies. Among others, the peeling-test method was developed to recast reliable data in describing decohesion of surfaces. Such methodology is affected by high operator dependency, due to manual application of the tape on the surface and high variability in the patch area and tape typology. Our study was aimed at improving the methodology by the implementation of a device able to warrant a well-defined pressure during the application, a constant strapping angle along with the standardization of the scotch tape area and typology, obtaining reliable semi-quantitative and qualitative analyses. The revised methodology was then tested on a cladded wall in the Staglieno Monumental Cemetery in Genoa. The site was addressed by multi-scale analysis (i.e., weathering maps sketched from macro-scale observation, surfaces analyses and micro-sampling through peeling). The application of the methodology allowed highlighting the presence of capillary rise up to 1-1.5 meters height and a more weathered central area. On the whole, our protocol allowed reproducible factual sampling, and, on statistically significant population, the categorisation of decay intensity.