The TAPPI T 835 standard specifies the determination method of water-absorption of corrugated media. The water-absorption test is used to evaluate its water-absorption. The standard describes in detail the test equipment, sample preparation, test steps and the method of calculating the results. Quantify the water-absorption energy of the material by placing the water droplets on the surface of the corrugated medium and measuring the time it takes for the water droplets to be completely absorbed. The test method is simple and fast. It is suitable for evaluating the performance of corrugated media in humid environments. It provides an important reference for quality control and application selection of Encasement materials. The standard is mainly applicable to the dielectric layer materials in the production of corrugated fibreboard.