The TAPPI T 464 standard specifies a method for measuring the water vapor transmittance (WVTR) of paper and Cardboard under high temperature and humidity conditions. The method uses the weighted method to measure the water vapor transmittance of materials at an environment of 37.8 ° C (100 ° F) and 90% relative humidity. This test is suitable for materials up to 3 mm thick, for thicker materials, it is necessary to ensure that the edge of the sample is completely sealed. This standard is important for evaluating the moisture resistance performance of paper and Cardboard when Encasement and Protecting products.