GB/T 13893.2-2019 "Paints and varnishes—Determination of resistance to humidity—Part 2: Condensation (exposure in a condensation-testing apparatus with a heated water tank)" is applicable to the determination of the resistance to humidity of coatings of paints and varnishes. This standard uses a condensation-testing apparatus equipped with a heated water tank. Test panels are placed in specific positions within the apparatus, and a condensation environment is generated by heating the water tank, exposing the coatings continuously to high-humidity condensation conditions. After the specified exposure period, the coatings are inspected for defects such as blistering, discoloration, and peeling to assess their resistance to humidity. The standard specifies requirements for temperature control of the apparatus, exposure time, and placement of test panels to ensure consistency of test results.