Exclusion of Gases and Vapors
As a rule, papers have only a limited ability to exclude gases and vapors. Of partic¬ular importance are the air permeability (e. g., for filtration properties) and the water-vapor permeability.
There are two standardized test methods available for the determination of the mean air permeability: the Bendtsen method (ISO 5636-3, 1992) and the Schopper method (ISO 5636-2, 1984).
A gravimetric method for the determination of water-vapor permeability is de¬scribed in ISO 12 572 (2001). This method is suitable for building materials. For foils, laminated paper and board also DIN 53 122-1 (2001) is recommended.