The effects of steaming of beech (Fagus orientalis L.) and sapele (Entandrophragma cylindricum) woods on the adhesion strength of varnish

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Abstract

In this study, it was investigated how steaming of beech (Fagus orientalis L.) and sapele (Entandrophragma cylindricum) woods effect the adhesion strength of some varnish types. With this objective, first of all, the surface roughnesses of the steamed and unsteamed specimens having tangential and radial surfaces and prepared from beech and sapele were measured (Kiliç et al., J Mat Proc Tech 2008, 199, 448). Subsequently, cellulosic, polyurethane and water-based bright varnishes were applied on these surfaces according to the principles stated in ASTM D 4541 and TS EN 24624 and the adhesion strength of the varnished layers were determined. According to the results of the study, the effects of the type of wood, steaming, surface and varnish types were found to be significant in the adhesion strength to the surfaces of the different varnish layers applied to the surfaces of different wooden materials. It was found that beech wood had a higher adhesion strength than sapele wood. The adhesion strength of steamed wooden materials had a lower strength compared with those that were unsteamed. The adhesion strength of specimens with a radial surface were found to be higher than the specimens with tangential surfaces. Whereas, in the varnish types, the highest adhesion strength was obtained with the polyurethane varnish, which completed the chemical reaction on the surfaces of the wooden material. In conclusion, it could be proposed to use beech wood materials having a radial surface in the jobs requiring a high adhesion strength, to sand once again the material due to the increase in roughness of steaming and to use polyurethane varnish. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

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