Advances in testing the interference of biocides on stone materials: A comparative analysis and guidelines for a standardised approach

Many biocidal products are applied to stone monuments as a conservative treatment against biodeterioration. However, checking national and international committees for the Conservation of Cultural Heritage and scientific literature, it stands out that most standards define single tests, but in the case of biocides, a well-defined standard methodology to check their interactions with the substrate is not drawn up yet. The present work thus provides comparative evaluations and suggestions to monitor the potential interference of biocides on stone materials. For this purpose, we built a dataset based on fifty scientific papers dealing with interference tests on biocides, and then we compared several methods and the obtained results, considering different biocides, stones and modes of application. The comparative data point out that the most investigated features are: changes in the surface colour, using colourimetry methods; water absorption, using capillary rise; contact sponge; contact angle; and morphology, using Scanning Electron Microscope (SEM). Here, we also provide a guidance standard on these methodologies, considering both in situ and in-laboratory analysis.(c) 2023 The Author(s). Published by Elsevier Masson SAS on behalf of Consiglio Nazionale delle Ricerche ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )