The ASTM D7709-12 (2023) standard provides test methods for the measurement of the water vapor transmission rate (WVTR) of pharmaceutical bottles and blisters. These methods are used to evaluate the barrier performance of pharmaceutical Encasements, including high-barrier and quasi-barrier containers, and are suitable for all types of consumer Encasements. The test determines the water vapor transmission rate by weight analysis and covers three test methods: bottles (Method A), shaped barrier blisters (Method B), and quasi-barrier blisters (Method C). The test environment is typically 40 ° C and 75% relative humidity. The standard is designed to ensure the Sensitivity and accuracy of the test data in order to accurately distinguish the water vapor barrier performance of different Encasements. Standard values are expressed in SI units for standard and referee tests.