The ISO 5637:2024 standard specifies a method for measuring the water absorption of paper and Cardboard after they have been completely immersed in water for a specified period of time. This method is suitable for paper and Cardboard with some water resistance, but not for paper with extremely strong water-absorption (such as toilet paper). The test evaluates the water-absorption energy of paper by immersing the sample in water and measuring its water absorption. This standard provides a uniform water-absorption test method for the paper industry, which helps to evaluate the performance of paper in a humid environment, ensuring its suitability in fields such as Encasement, printing, etc.