Humidity and heat resistance test, also known as humidity test, is used to evaluate the resistance of coatings to high temperature and humidity. Humidity and heat resistance test is also a method to test the corrosion resistance of coatings, so it is
usually carried out at the same time as salt spray test. Because temperature and humidity are the main influencing factors in the humidity and heat resistance test, special attention should be paid to the regulation and control of temperature and
humidity regulating box in the whole process of each test so as to avoid affecting the test results.
The wet-heat resistance test is usually carried out by two methods: condensation wet-heat method: placing the sample in a closed test box with temperature of (38 (+2)degrees C and relative humidity of not less than 98% (see Fig. 4-18), using
the very fine temperature difference between the test sample and the surrounding steam to form condensate water on the sample plate, and evaluating the water permeability resistance of the sample coating. The second is non-condensation wet-thermal
method: the samples are placed in a ventilation test box with temperature of (40 (+2)degrees C and relative humidity of not less than 95% to evaluate the wet-heat resistance of the sample coating.
For the evaluation of the samples, the grade of foaming, cracking, rusting and shedding of the coatings were observed according to CB/T1766-1995 standard, and the maximum difference of the parallel samples was taken as the test results.