The European standard “EN 15457 Paints and varnishes - Laboratory method for testing the efficacy of film protectors used in coatings against fungi” describes a laboratory test method for determining the biocidal or biostatic efficacy of single active substances or combinations thereof used in protective films of paint or varnish coatings against fungal growth.
In principle, to determine the fungicidal efficacy of film protectors in a coating, the coating material is applied to a substrate conditioned according to the EN 23270 standard, placed on an agar surface, inoculated with a standard fungal spore suspension, and incubated. After incubation, conclusions about the fungicidal efficacy of the film protectors in the coating can be drawn from the intensity of fungal growth on the surface of the test sample. The method described here is a semi-quantitative, comparative method between coatings with and without film protectors.
The EN 15457 standard is particularly important for coatings used on wood and masonry where fungal growth can cause discoloration, surface deterioration, and loss of aesthetic and protective performance.
The purpose of this standard is to provide a controlled laboratory procedure to determine the biocidal or biostatic efficacy of individual active substances or combinations of active substances incorporated into coating film preservatives. Simply put, the test helps answer the question: can a preservative incorporated into a coating effectively prevent or limit fungal growth in the coating film? This makes the standard useful during formulation development, preservative selection, quality control, and comparative evaluation of coating systems.
Paints and protective coatings can be exposed to moisture, humidity, temperature fluctuations, and other environmental conditions that promote fungal growth. Fungi growing on a coating can cause visible staining and discoloration, negatively impacting the appearance and service performance of the coated surface. Therefore, film protectors are added to some coating formulations to help control fungal growth after coating application.
The EN 15457 standard provides a standardized laboratory approach for evaluating these preservatives. By using a defined test method, manufacturers can compare different active ingredients or combinations of preservatives under controlled conditions, rather than relying solely on field observations.
The EN 15457 standard focuses specifically on the effectiveness of active substances used for film protection. The method can evaluate the following:
The aim of the test is to determine whether the protective system can prevent fungal growth on the coating film.
The exact organisms, preparation requirements, exposure conditions, evaluation criteria, and reporting requirements should be taken directly from the existing EN 15457 standard, rather than being inferred from general fungal resistance tests.
The EN 15457 standard applies to active substances used for film protection in coatings designed for the following applications:
However, this does not apply to marine coatings. It also does not apply to coatings that are not susceptible to fungal growth.
An important distinction is that the EN 15457 standard evaluates the film protector, not its ability to protect the substrate beneath the coating. For example, the test should not be interpreted as a general measure of the biological resistance of wood under a coating.
Several topics are specifically outside the scope of this standard:
Therefore, a coating that performs well according to the EN 15457 standard should not automatically be considered resistant to all environmental aging conditions.
The EN 15457 standard is important because fungal resistance can be a fundamental performance characteristic for coatings used in environments where moisture and biological contamination are possible. The various benefits offered by this standard include:
The EN 15457 standard may be applicable to manufacturers and laboratories working with the following:
This standard can be particularly useful during the development of coatings where maintaining a clean and aesthetically acceptable surface is important.
In conclusion, the EN 15457 standard provides a standardized laboratory method for evaluating the effectiveness of film protectors added to paints and varnishes against fungal growth. Its main application area is the evaluation of active substances used to protect coating films, especially for wood and wall coverings.
This standard is valuable because it allows coating manufacturers, preservative suppliers, and testing laboratories to evaluate fungal control performance using a consistent laboratory methodology. This standard assesses the effectiveness of film preservatives against fungi and is not a general assessment for substrate durability, environmental safety, marine coating performance, or aged coating performance.
For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services in accordance with the EN 15457 standard.
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