PEER-REVIEWED ARTICLE bioresources.com Gáborík et al. (2017). “Pressing aspen surface,” BioResources 12(1), 82-94. 82 Quality of the Surface of Aspen Wood after Pressing Jozef Gáborík, a and Milan Gaff, b * Daniel Ruman, b Miroslav Gašparík, b Tomáš Svoboda, b Vojtech Vokaty, b and Adam Síkora b This paper explores changes in the quality of the surface of aspen wood after pressing. Pressing, a type of processing, facilitates changes in surface quality and smoothness, thereby producing wood suitable for the furniture industry. The results obtained for the pressed wood surface were compared with those obtained for wood surfaces that were not subjected to pressing. Attention was paid to the impact of moisture, the degree of compression, and plasticizing by steam. The change in smoothness/ roughness was monitored in both the longitudinal and transverse directions (relative to the grain). The contact method was used to measure the roughness both before and after pressing. The independent variables of moisture content and degree of compression had the greatest impact on the smoothness/roughness. Plasticizing by steam had no greater impact. Therefore, the non-plasticized aspen wood was determined to be more suitable for the given purpose. Keywords: Smoothness; Roughness; Roughness reduction; Plane milling; Cyclic pressing; Steaming; Aspen; Surface quality Contact information: a: Department of Furniture and Wood Products, Technical University in Zvolen, T. G. Masaryka 24, Zvolen, 96053, Slovakia; b: Department of Wood Processing, Czech University of Life Sciences in Prague, Kamýcká 1176, Praha 6 - Suchdol, 16521, Czech Republic; * Corresponding author: gaffmilan@gmail.com INTRODUCTION Wood is a renewable raw material with properties that place it in competition with other materials. Wood-processing companies must therefore search for new processes to reduce the adverse properties of wood and widen its scope of applications in non-traditional areas. As a natural material, wood has unique properties based on its natural vague. However, these properties are not always sufficient for the manufacture of modern and future products. Therefore, the wood can be treated by various processes in order to change its properties as required. Targeted modification, mainly of soft deciduous wood species of less frequent application, may allow these species to be used in the furniture industry. For this reason, we have focused on aspen wood. Its longer fibers, lower density, and pale (white) color make it appealing for molded furniture production. Pressing enables the modification of numerous wood properties, such as density, hardness, stability, bendability, surface smoothness, etc. Wood pressing may only be carried out mechanically, with eventual joint action of the heat; this case is more frequent. Densification improves the mechanical properties of all wood species. Due to the effect of heat and moisture, the substances constituting wood cellulose structure are softened. Pressed wood mechanical properties change as a function of the pressing degree and the position of pith rays (Blomberg 2006).