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1994
Journal Article
Titel
The dynamic contact angle - a characteristic to predict the lifetime of a wood topcoat
Abstract
Documentation of changes in liquid water protection is of utmost importance for the characterization of the durability of an exterior wood coating. The use of the water-uptake-coefficient wt and the dynamics of a liquid water drop contact angle for the determination of lifetime expectation is described. Both methods are found to give equivalent information regarding changes in water protection of six mainly water-borne unweathered and 6-month weathered exterior wood coatings. The advantages of the contact angle method are outlined. Furthermore, a theoretical approach is presented to relate the observed proportionality of the contact angle with square root of time to diffusion controlled processes on the coatings surface. Coatings used for half-timbered houses need to be investigated with regard to their hydrolitic qualities. In order to prevent a dangerous moistening of the wood, it is of utmost importance to know the water absorption as well as the water desorption through the coatin g system. This work reports about a method able to describe the interaction between water absorption and desorption on a representative dispersion system applied on different wood species. The wood species were chosen with respect to their occurence in half-timbered wooden constructions. g system. This work reports about a method able to describe the interaction between water absorption and desorption on a representative dispersion system applied on different wood species. The wood species were chosen with respect to their occurence in half-timbered wooden constructions.