GB/T 1733-1993 "Determination of water resistance of paint film" standard describes in detail two methods to evaluate the durability of Coating paint film under humid conditions. Method A is the immersion test method, and Method B is the immersion boiling water test method. During the test, the sample is checked for loss of gloss, discoloration, blistering, wrinkling, peeling or rusting on its surface by soaking in a Glass sink, and the recovery time of the paint film is recorded. The standard specifies the selection of baseplate, the preparation of the test plate, drying conditions, the detailed steps of the thickness measurement of the paint film, and the content requirements of the test report. Applying to all types of coatings and varnishes, the standard provides a reliable test method for evaluating their durability in wet environments, helping to ensure that products meet mass and performance standards.