Effects of impregnation with boron compounds on the surface adhesion strength of varnishes used woods
The aim of this study was to determine the effects of impregnation with boron compounds on the surface adhesion strength of varnishes used woods. For this purpose, the test specimens prepared from Oriental beech (Fagus orientalis Lipsky) and European oak (Quercus petreae (Matt.) Liebl.) which met the requirements of ASTM D 358 were impregnated according to ASTM D 1413 with boric acid (Ba) and borax (Bx) by vacuum technique. After impregnation, surfaces were coated with cellulosic, synthetic, polyurathane, water-based, acrylic and acid hardening varnishes in accordance with ASTM D 3023 standards. According to ASTM D 4541 standards, the surface adhesion strength of specimens after varnishing process was determined. Considering the interaction of wood type, impregnation material and varnish type, adhesion strength values were found the highest in Oriental beech + boric acid + synthetic varnish (6.240 Mpa) and the lowest values in European oak + borax + cellulosic varnish (2.080 Mpa). Consequently, impregnation of wood material with boron compounds (boric acid: 3.677 Mpa and borax : 3.732 Mpa) showed increasing impact on the surface adhesion strength of cellulosic, synthetic, polyurathane, water-based, acrylic and acid hardening varnishes.
Key words: Adhesion strength, impregnation, boric acid, borax, varnishes, finishing, wood.