Evaluation of Wettability, Surface Free Energy, and Janka Hardness of Steamed Beech Wood

The steaming of wood changes its physical, mechanical and chemical properties in a complex way. The information about the wettability, surface free energy, and Janka hardness of steamed beech false heartwood and sapwood is not sufficient; these properties were therefore the main focus of this article. Wettability was determined by contact angle measurement with standard testing liquids. The steaming regime was a significant factor for wetting with redistilled water, and it had a mutual interaction during wetting with diiodomethane along with the factor wood zone. The steaming regimes also significantly influenced the surface free energy of the beech wood. According to the contact angles and surface free energy values, the Mode I steaming regime showed a better wettability than the Mode II regime. Analysis of the Janka hardness values showed that wood zone, steaming regime and anatomical direction significantly influenced the hardness in a mutual interaction. Beech wood steamed with the Mode I steaming regime showed a significantly lower Janka hardness in all anatomical directions; the Mode II steaming regime showed a significantly lower hardness only in the cross directions. The statistical difference between false heartwood and sapwood hardness was not significant only in the tangential direction for both steaming regimes and untreated wood.