Comparing Wettability and Surface Free Energy of False Heartwood, Ripe Wood and Sapwood in Beech (Fagus sylvatica L.)

False heartwood is a common defect in beech wood. If the false heartwood is healthy and without microbial attacks, it is possible to utilize such material. Application of adhesives and coatings is an important part of the wood furniture industry. Studying wood surface properties provides answers to problems in application of glues, coating materials, and similar. Comparing wettability and surface free energy of false heartwood, ripe wood, and sapwood zones of beech was the focus of this paper. Two-way ANOVA with Duncan post-hoc test of multiple comparison was used for testing of the hypotheses and statistical evaluation of the results. The zones were also examined with light microscopy. Two testing liquids were used in wettability experiment – redistilled water and diiodomethane. Ripe wood showed the best wettability for both testing liquids among the wood zones. Significant differences in contact angles at the beginning of the wetting process, equilibrium contact angles, and surface free energies were found in almost all pairwise comparisons of the wood zone and testing liquid factors. The pairs where significant difference was not found were as follows: false heartwood and ripe wood in testing with redistilled water, and ripe wood and sapwood in testing with diiodomethane. Equilibrium times in all wood zones for both testing liquids were also statistically evaluated. Significant differences were found in all wood zones in testing with redistilled water. In testing with diiodomethane, equilibrium time for false heartwood was significantly different from ripe and sapwood zone equilibrium times.