A paint product manufacturer was developing a new formulation and contacted EMSL to help determine whether the new product would resist fungal growth. EMSL recommended ASTM D5590 which is an accelerated four week agar plate assay to determine resistance of paints and coatings to fungal defacement. Defacement of paint by fungal growth (mold, mildew) is a common phenomenon. It is generally known that differences in the environment, lighting, temperature, humidity, substrate pH, and other factors in addition to the products composition affect the susceptibility of a given painted surface. This test method provides a means to comparatively evaluate different coating formulations for their relative performance under a given set of conditions. EMSL was able to show that the client’s product performed well under these test conditions and resisted fungal growth.