Water Vapor Transmission ASTM E96
The test evaluates the water vapor transfer through semi-permeable and permeable samples. The data can be used by manufacturers and designers and is often important in packaging applications.
A cup is filled with distilled water leaving a small gap (0.75" to 0.25") of air space between the specimen and the water. The cup is then sealed to prevent vapor loss except through the test sample. An initial weight is taken of the apparatus and then periodically weighed over time until results become linear. Caution must be used to assure that all weight loss is due to water vapor transmission through the specimen.
4 x 4 inch specimen
Graph of weight versus time or percent transmission versus time
**Please note that this test description is intentionally generic in nature and aimed at providing a descriptive summary to enhance test understanding. Standards can be obtained from appropriate standard authorities.
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