Today's better barriers require a precision in permeation testing not available even as recently as 1985. New processes such as coextrusion, new materials such as EVOH, and new uses for barriers, such as controlled at mosphere packaging, have placed new requirements on the method and preci sion for testing good barriers. This paper outlines the basic parameters which affect permeation, the ASTM and TAPPI Methods which are currently in use, and the apparatus which is required. The current state-of the-art in the most accurate methods for testing oxygen and water vapor available today is ex plored, along with an analysis of expected precision of measurements.
