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This document specifies a method for the determination of the water vapour transmission rate (often erroneously called “permeability”) of sheet materials.

This method is not generally recommended for use if the transmission rate is expected to be less than 1 g/m2 per day or for materials thicker than 3 mm. In such cases the method specified in ISO 9932 is preferred.

The method cannot be applied to materials that change dimensionally (shrink or expand) to an appreciable extent under the test conditions used. In the case of materials that are damaged by hot wax, only mechanically-sealed test dishes can be used.

For some purposes it may be necessary to determine the transmission rate of creased material; a procedure for this is given in Annex B.