scope:

This International Standard specifies a method for determining the water-vapour transmission of paints, varnishes, coatings, coating systems and related products. The standard supplements ISO 12572. As far as possible the procedure, the definitions and the calculations have been taken over from ISO 12572. It is recommended here to consult the procedures specified in ISO 12572 as further explanations to this standard. Water-vapour transmission is of greatest interest under conditions of high humidity. For this reason, the wetcup method has been adopted as the reference method. By agreement, other procedures and conditions like the dry cup method may be used. A water vapour transmission rate V of more than 680 g/(m² · d) (sd of less than 0,03 m) will not be accurately quantified by the test method described in this standard.