Standard Test Method for Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber. ASTM D3273-16.

Test not accredited in our laboratory.

ASTM D3273 describes an accelerated test to determine the resistance of coating or coating products used indoors to the growth of filamentous fungi. It is used to evaluate the effectiveness of these coatings in indoor environments that promote fungal growth and to evaluate the compounds that can inhibit that growth and the concentrations of use of these components.

To analyze the resistance of the test coating, it must be applied on test panels. Those panels can be: ponderosa pine sapwood panels (75 mm x 100 mm and approximately 13 mm thick), drywall (75 mm x 100 mm and 13-25 mm thick,) or other surfaces depending on the actual coating application. Whenever possible, the dimensions of the test panels should be those indicated by the standard. Test panels must be provided by the customer. The coating must be applied in two layers and on both faces and all edges of the panels. For the test, 3 panels with the coating to be analyzed and 3 control panels must be used, which can be uncoated panels or with a coating that is not resistant to the growth of fungi.

The test is carried out in a small environmental chamber where the panels are kept at a temperature of 32.5°C ± 1°C and a relative humidity of 95% ± 3% for a period of 4 weeks to evaluate the relative resistance of the films of coating to the superficial growth of filamentous fungi in a strict indoor environment. The test panels are placed vertically on a tray containing greenhouse compost soil, inoculated with the three test fungi Aureobasidium pullulans, Aspergillus niger and Penicillium spp. After 4 weeks, the growth of fungi on the surfaces of the treated panels and on the control panels is evaluated, and the fungal growth or deterioration existing on the panels is assessed, assigning a gradation from 0 to 10. A grade of 10 indicates that there is no growth or disfigurement on the test pieces, while a grade of 0 implies that the surface has been completely disfigured. Therefore, the test results can be used for a comparative evaluation of the strength of interior coatings. A better qualified coating implies a better result in the actual end use.