Impact of the Aging Process on the Ability of Decorative Materials Containing Biocides to Support Fungal Growth

Building and finishing materials are among the main sources of indoor air pollution and can provide ideal substrates for microbial growth. Environmental factors can induce physico-chemical aging of these materials, altering their composition and increasing their vulnerability to microbial growth. To mitigate this risk, manufacturers are increasingly adding biocidal agents to these materials to prevent microbial contamination. The aim of this project was to study the sensitivity of two different acrylic paints to fungal growth, before and after an aging process, and to assess the impact of aging on the effectiveness of the biocides contained in these materials. To do this, two paints (antifungal and normal paint) were applied to a wall covering (polyester-cellulose) before being subjected to accelerated aging. The later process was based on the addition of detergent or water and exposing the material to a visible light spectrum, moderate temperature (38 ± 6 °C), and ambient relative humidity (25 ± 17%). Prior to 30 days of incubation, the aged and unaged (“native”) materials were inoculated with fungal spores using a dry aerosolization system. Fungi behavior was then evaluated by the culture method. The results showed that the native and water-aged normal acrylic paint supported fungal growth at 95 ± 5% relative humidity. However, the use of the cleaning product during the aging process provided additional resistance of the materials against fungal growth. On the other hand, the antifungal paint showed no visible growth due to its biocide content. The accelerated aging and incubation processes led to the depletion of the biocides and thus a decrease in their effectiveness against mold development.

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