Antibacterial efficiency over time and barrier properties of wood coatings with colloidal silver.

This work aims to represent a standard application for understanding the extent of the antibacterial efficacy of coatings with different amounts of colloidal silver on wooden surfaces over time. The key variable that was intended to be evaluated in this study was the "time efficiency," with concerns about the possible efficacy in the durability of the surfaces. By highlighting the "expiry date" of the agents, as in the case with other products, the study aimed to confirm the validity of the simulation tests conducted in the laboratory with degradation tests. Furthermore, the role of the silver amount on the barrier performance of the coatings was assessed by liquid resistance, water uptake, and perspiration tests, evaluating the aesthetic durability of the coatings by means of colorimetric analyses. Ultimately, this work demonstrates that these coatings may represent alternatives in terms of prolonged antimicrobial activity when compared with the biocide agents currently in use, capable to offer good resistance to detergent solutions and to water. Nevertheless, due to silver's susceptibility to extended exposure to acidic solutions, the findings of the research discourage the utilization of colloidal silver in wood paints intended for use in public settings. KEY POINTS: • Colloidal silver does not alter the deposition process and does not introduce defects in the wood paint. • Coatings containing silver show high antimicrobial activity over time, against both E.coli and S.aureus. • The silver-based filler resists contact with detergents and aqueous solutions but suffers oxidation processes in acidic environments.