Moisture resistance refers to the resistance of the coating film to the action of a humid environment. Usually, the coating sample is tested under high humidity conditions. my country has equivalently adopted the IS06270-1980 standard and formulated GB/T13893-92 "Determination of Moisture Resistance of Paints and Varnishes by Continuous Condensation Method", which stipulates the method for testing the moisture resistance of coating films in high humidity environments with continuous condensation. It is used to determine the moisture resistance of coatings on porous substrates (such as wood, cement asbestos board) and non-porous substrates (such as metal). The standard stipulates that a moisture resistance Tester is used, the sample is placed on the top cover of the instrument, the temperature of the Water Bath of the instrument is controlled at 40°C ± 2°C, the temperature at 25mm below the test sample is kept at 37°C ± 2°C, and the coating surface is continuously in a condensation state , according to the specified time for testing. At the end of the test, remove the sample panel, check its surface damage immediately, and evaluate its moisture resistance according to the GB/T1740-79(89) sample rating method or agreement.
In addition, there are also detection methods at room temperature. For example, the Japanese JISK5661-1970 standard for fire-resistant coatings for buildings stipulates moisture resistance test items. After standing vertically for a few days, place it vertically in a container with a temperature of 20°C±3°C and a humidity of about 90% for 72 hours, then take it out and check the condition of the coating film.
