GB/T 2679.2-2015 "Paper and board—Determination of water vapour transmission rate—Gravimetric (dish) method" specifies the gravimetric (dish) method for determining the water vapour transmission rate of thin materials and the crease water vapour transmission rate. It is applicable to materials such as tissue paper and is a modified adoption of ISO 2528:1995. In this method, a specified amount of distilled water is placed in a transmission dish, covered with the specimen and sealed, then placed in a constant temperature and humidity environment. The mass is measured periodically, and the water vapour transmission rate is calculated according to a formula. For the crease water vapour transmission rate test, the specimen is first folded and creased before being measured following the same procedure. The standard references GB/T 450 and GB/T 10739 to ensure uniformity and accuracy in the determination of water vapour transmission rate, providing a basis for evaluating the performance of thin materials.