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2004
Conference Paper
Titel
Measuring wet adhesion of wood coatings by pull-off test
Abstract
Most of the currently used exterior arcrylic coating systems are characterised by their ability of being penetrated by moisture both into and out of the wood. Normally, a good adhesion of these coating systems at a higher load of humidity cannot be achieved. In cases of an already damaged coating film or an increased presence of humidity (i.e.construction during winter) in the boundary to the wood surface, only a short-term exposure to water is needed to detach a coating film with an insufficient wet adhesion completely. At present, the adhesion test is being performed according to the European Standard EN ISO 24624; Cross-cuts test ISO 2409; 1994. The long-term use of this test method for exterior wood coatings showed that compareable and repeatable results could not relieable be guaranteed. This new fixed method is suitable for the testing of exterior wood or wood based material coatings and describes a method following EN ISO 24624 for the testing of the wet adhesion of a single-layer or multilayer coating system consisting of paints, varnishes or similar products. In this process the force, which is necessary to detach or pull-off the coating vertically from the substrate is measured. Furthermore, the modus of fracture of the coating is assessed. The reproducibility and repeatability of the new method is well.
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