Gloss of thermally densified alder (Alnus glutinosa Goertn.), beech (Fagus sylvatica L.), birch (Betula verrucosa Ehrh.), and pine (Pinus sylvestris L.) wood veneers

Abstract

Thermo-mechanical densification of wood is performed to improve physical and mechanical properties of wood. During this treatment aesthetic properties of wood, including gloss, also change. Therefore, the purpose of this study was to determine the effect of short-term thermo-mechanical (STTM) densification in different wood species (alder (Alnus glutinosa Goertn.), beech (Fagus sylvatica L.), birch (Betula verrucosa Ehrh.), and pine (Pinus sylvestris L.)) on their gloss changes. Commercial wood veneers were densified in a hot plate press for 4 min at temperatures of 100, 150 and 200°C, pressures of 4, 8 and 12 MPa. Gloss was evaluated at 20°, 60°and 85°a ngles of incident light using PICO GLOSS 503. Gloss measurements showed an enhancement of aesthetic properties of densified wood. Findings of this study indicated that both densification temperature and pressure have a significant effect on wood gloss. Gloss values of densified wood increased with increasing densification temperature and pressure for all investigated species. Compared to nondensified wood, gloss (85°) values (across/along the grain) for alder, beech, birch and pine increased after treatment to 2109.1/2376.9, 1728.6/2311.1, 2787.5/3000, and 2591.7/ 1216.7 %, respectively. The greatest gloss values were recorded at 200°C and pressure of 12 MPa for all tested angles of incident light and for all densified wood samples. Gloss changes for birch were the highest, but the glossiest surface was observed for pine among all investigated species after wood densification.

Quality of Silicone Coating on the Veneer Surfaces

“…The gloss can also be affected by a different type of modification of veneer. Bekhta et al (2014) have described changes in the gloss of veneers densified by heat. …”

Some Coating Properties of Black Alder Wood as a Function of Varnish Type and Application Method

“…Gloss quality depends on several factors including wood species, chemical composition, coating system, varnish type, number of layers, and substrate preparation (Zivkovic 2004;Cakicier et al 2011;Bekhta et al 2014).…”

Effects of Heat Post-Treatment on Dimensional Stability and Water Absorption Behaviours of Mechanically Densified Uludağ Fir and Black Poplar Woods

“…In particular, thermal, thermo-mechanical, and thermo-hydro-mechanical treatments of wood have been widely studied and applied to improve its properties (Bekhta et al 2014a). It is well known that many of the properties of solid wood correlate with its density and can thus be enhanced by increasing the density (Sandberg et al 2013).…”

“…The main aim of wood densification is to improve the mechanical properties of wood by eliminating its porosity without the use of chemical additives (Sandberg et al 2013;Laine et al 2013). Moreover, depending on densification and post-treatment conditions, it has been stated in different studies that surface quality (smoothness, brightness, colour, hardness), wetting behaviour, and durability properties can be developed in densified wood material (Welzbacher et al 2008;Ünsal et al 2011;Arruda and Del Menezzi 2013;İmirzi et al 2014;Bekhta et al 2014aBekhta et al ,b, 2015Pelit et al 2015a). The main detriment associated with densification in an open system is the fixation of the compressive deformation.…”