DIN EN ISO 7783 — Determination of water vapour transmission properties of coatings
DIN EN ISO 7783 specifies a cup method to determine the water vapour transmission properties of paints, varnishes and related coatings. The procedure produces comparable, reproducible values for water vapour flux and supports material selection, quality control and research. 
Overview
The standard defines terms, test assembly, specimen preparation, test conditions and calculation methods. It is written to align closely with EN ISO 12572 so that results are consistent across related test methods. 
Purpose and scope
DIN EN ISO 7783 applies to self-supporting and non-self-supporting coatings and coating systems, and is intended for paints and varnishes used on porous and non-porous substrates. It is used to assess how coatings allow moisture to pass, which is important for durability and substrate protection. 
Test principle
The method uses permeability cups in either the wet cup or dry cup configuration. A film or coated specimen seals a cup that contains either a desiccant (dry cup) or a saturated salt solution (wet cup). The mass change of the cup over time gives the water vapour flux, from which WVTR or related values are calculated. 
Application areas
Material development, testing labs and quality control
Manufacturers and laboratories use the cup method for R&D, batch control and to study how variables like film thickness, temperature or humidity affect vapour transmission. Results support product specs and conformity checks. 
Industrial coatings and corrosion protection
In industrial environments, coatings must balance barrier properties with breathability to protect substrates and prolong service life. Testing to ISO 7783 provides comparable permeability data for selecting and verifying protective systems.  
Façade and exterior coatings
For exterior paints and renders, vapour permeability determines how well moisture inside a wall can escape. ISO 7783 measurements help classify coatings and choose systems that avoid moisture accumulation and damage. 
DIN EN ISO 7783 Certified Machines
Here are four machines that comply with DIN EN ISO 7783:
- With GraviTest the determination of water vapour transmission rates of polymeric films and other sheet materials by gravimetric method becomes mere child’s play.
- The new Automatic Gravimetric WVTR Tester GINTRONIC GraviTest 6250 comes with a 0.01mg balance as a standard feature. The 0.01 mg balance makes WVTR measurements of low perm materials 2-3 times faster than the previous generation systems.
- The same instrument like GINTRONIC GraviTest 6300/6400, but also for samples with a thickness up to 50mm.
