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Testing principles and Reagents in EN ISO 11998 (Paints and varnishes-Determination ofwet-scrub resistance and cleanabilityof coatings)
Posted Date:2025/10/14
4 Principle
4.1 Wet-scrub resistance
The test coating is applied to a test panel using a film applicator at the appropriate gap clearance. After drying and conditioning, the coated panel is weighed and subjected to 200 wet-scrub cycles in a scrub testing machine.
NOTE Some classification standards, e.g.EN 13300, require fewer scrub cycles.
It is then washed, dried and weighed again to determine its loss in mass, from which the mean loss in film thickness is calculated.
Through comparison of the mean loss in film thickness with a specified value, as agreed between interested parties, the coating can be rated in wet-scrub resistance classes.
4.2 Cleanability
For the determination of cleanability, soiling agents are applied to similarly prepared coated panels. The soiling agents specified are left in contact with the coating film for a specified time. The coated, soiled panels are then subjected to 200 wet-scrub cycles.
When the applied soiling agent is observed to be removed and the coating is wet-scrub resistant, the coating is said to be cleanable in terms of the soiling agent used.
5 Reagents
5.1 Washing liquid
Use a 2,5 g/l solution of sodium n-dodecylbenzenesulfonate in water conforming to the requirements of grade 3 of 1S0 3696. Allow the solution to stand before use until all air-bubbles and foam have dissipated.
5.2 Soiling agents
The soiling agents and manner of application shall be agreed between the interested parties.