EN 927-4 Paints and Varnishes, Coating Materials and Coating Systems for Outdoor Wood, Part 4: Test for Evaluation of Water Vapor Permeability

EUROLAB laboratory provides testing and compliance services within the scope of EN 927-4 standard. This part of EN 927 specifies a test method for assessing the water vapor permeability of cladding systems for exterior wood by measuring the absorption and desorption of water vapor by veneered wood panels.

Results are expressed as the mass in grams of water gained and lost over two 14-day periods under specified conditions.

The treatment of external wooden surfaces has both aesthetic and protective functions. A vital purpose of a coating system is to protect the wood against aesthetic degradation (e.g. blue spot attack) and dimensional changes. Because such attacks are mainly caused by the high moisture content in wood, knowledge of the relative water vapor permeability properties of coating materials applied to exterior wood is helpful in selecting products for specific end-use applications as described in EN 927-1.

It is known that the water permeability of some types of coatings can change significantly with relatively short exposure to water. For such coatings, the water permeability values ​​obtained during brief contact with water may not be representative of those obtained during extended service. Therefore, all coatings must undergo a leaching procedure before the absorption cycle begins.

EUROLAB assists manufacturers with EN 927-4 test compliance. Our test experts, with their professional working mission and principles, provide you, our manufacturers and suppliers, the best service and controlled testing process in our laboratories. Thanks to these services, businesses receive more effective, high-performance and quality testing services and provide safe, fast and uninterrupted service to their customers.