Hydrogels containing Thymus vulgaris essential oil as a novel approach for cleaning monument glazed tiles

Abstract Preservation of ancient works is one of the most important concerns of those interested in cultural heritage. Restorers use various physicochemical and biological methods to preserve and/or clean ancient objects. One of the cleaning methods is using herbal essential oils (EOs). Since EOs are often volatile, their incorporation into polymers can mitigate this drawback. Here, the antimicrobial properties of Thymus vulgaris EO were evaluated through the disk diffusion method against microbial strains, which had been isolated from our previous work. To reduce its volatility, two commercial polymers, alginate and polyvinyl alcohol, were used, and their antimicrobial properties were evaluated. Next, the tests were done on tile models. The results showed that the EO was effective against all selected microbial strains. Furthermore, alginate hydrogel containing EO showed the best antimicrobial activity, suggesting its potential as an effective cleaning method. Further investigation is necessary to ensure that this hydrogel has no undesirable impacts on historical substrates.