GB/T 1728-2020 "Methods for Determination of Drying Time of Paint Films and Putty Films" is applicable to the testing of the drying time of paint films and putty films. Depending on the drying stage, methods such as the finger-touch method, filter paper pressing method, cotton ball pressing method, and blade method are used in conjunction with a drying time tester (including a stopwatch and weights). Under conditions of 23±2°C and relative humidity of 50±5%, the corresponding method for each drying stage is applied, and the time from coating application to the attainment of the specified drying state is recorded. The operational details of each method and the criteria for determining the drying state are clearly defined, providing a unified approach for evaluating the drying performance of coatings.