Plastics Technology Laboratories  

Water Vapor Transmission


Click on the picture for a larger view

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.

Test Procedure:
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.

Specimen size:
A 4 x 4 inch specimen is often used, as it needs to fit exactly over the liquid container.

Graph of weight versus time or percent transmission versus time

Equipment Used:
Water vapor transmission cups
Mettler Balance

Intertek PTL Overview
Contact Us
Services & Tech Info
Industry Segments
Industry Segments


**Please note that this test description is intentionally generic in nature and aimed at providing a descriptive summary to enhance test understanding. For more information please contact a Intertek PTL Technical Representative at . Due to copyright restrictions, we are not able to provide copies of standards. Standards can be obtained from appropriate standards authorities.

Back to Testlopedia