ASTM D5590-17 (2021) Standard Test Method for the Determination of Resistance of Paint Films and Related Coatings to Fungal Fouling by Accelerated Four-Week Agar Plate Method specifies the four-week Agar plate method for evaluating the resistance of paint films and related coatings to fungal fouling. The test method uses accelerated exposure conditions, placing paint film coatings on fungal foster bases, and observing their inhibition on fungal growth to determine the antifungal performance of coatings. The standard specifies specific requirements for experimental design, Sample Handling, exposure time, etc. to ensure the accuracy and repeatability of results. This test method is applicable to architectural coatings, industrial coatings, and Miscellaneous similar products to help manufacturers evaluate the protection of coatings against fungal growth in humid environments, thereby improving the durability and long-term application performance of coatings.