The Effect of the Mechanical Densification Process in Wood Material on the Surface Adhesion Resistance of Varnishes

Abstract This research was carried out to find out the impact the mechanical densifying process has on wood material on the varnish adhesion resistance to surface. To this end, the experiment samples acquired from black pine (Pinus nigra) and Uludag Fir (Abies bornmulleriana Mattf) were subjected to densification in a hydraulic press at 140°C and a rate of 25% and 50% with a direction of radial. Following the process of densification, the sanded and unsanded samples were varnished with cellulosic and polyurethane varnishes, afterwards the surface adhesion resistance of the varnishes was determined. Regarding the three-way interaction between densification ratio, surface treatment and wood type, the highest surface adhesion resistance of the varnish layer was found in black pine + unsanded surface + 25% densification (1.98), and the lowest was in Uludag Fir + unsanded surface + 50% densification (0.99). Concerning the triple interaction of varnish type, concentration ratio and surface treatment, the highest surface adhesion resistance of the varnish layer was found in the polyurethane varnish + non-densified control group + sanded surface (2.23), and the lowest was in cellulosic varnish + non-densified control group + sanded surface (1.02). Approximate values were obtained for the densification process. It can be stated that the densification process creates high adhesion values for the polyurethane varnish in the black pine wood type. The sanding process has an intensifier effect on these values, and the products which were obtained from the polyurethane varnished samples do not require sanding. Considering these situations can provide significant advantages in projects with wood materials subjected to the densification process.