Formaldehyde Emission, Surface Roughness, and Some Properties of Plywood as Function of Veneer Drying Temperature Ismail Aydin and Gursel Colakoglu Karadeniz Technical University, Faculty of Forestry, Forest Industry Engineering Department, Turkey Abstract: The drying of veneer is an essential part of the veneer-producing pro- cess to aid the gluing during the manufacture of the plywood and LVL. Determin- ing the optimum veneer drying temperature without loss of bonding strength is also very important from an industrial viewpoint. Increased temperatures are being used in veneer drying to reduce the overall drying time and increase capacity. In this study, 2-mm-thick rotary-cut veneers obtained from alder (Alnus glutinosa barbata) logs were used as materials. After rotary cutting, veneer sheets were classified into four groups and dried at 20, 110, 150, and 180  C. Three-ply and 6-mm-thick plywood panels were manufactured with urea formaldehyde (UF) adhesive. Surface roughness and color variations of veneer sheets and shear strength, bending strength, equilibrium moisture content, and formaldehyde emission of plywood panels were determined based on veneer drying tempera- tures. According to the results, the smoothest surfaces were obtained for 20  C drying temperature while the highest values of surface roughness were obtained for 180  C. Total color change value (DE  ) increased linearly with increasing dry- ing temperature. Shear strength values of plywood panels decreased clearly with increasing veneer drying temperature. While the least bending strength mean value was obtained for 20  C drying temperature, no clear difference was found for bending strength of plywood panels manufactured from veneers dried at 110, 150, and 180  C. Equilibrium moisture content (EMC) of plywood panels decreased with increasing veneer drying temperature and as the veneer drying temperature was increased, formaldehyde emission values of plywood panels increased. Keywords: Drying temperature; Plywood; Veneer; Surface properties; Formalde- hyde emission Correspondence: lsmail Aydin, Karadeniz Technical University; Faculty of Forestry, Forest Industry Engineering Department, Trabzon 61080, Turkey; Tel.: 90 462 3773258; Fax: 90 462 3257499; E-mail: iaydin@ktu.edu.tr Drying Technology, 23: 1107–1117, 2005 Copyright Q 2005 Taylor & Francis, Inc. ISSN: 0737-3937 print/1532-2300 online DOI: 10.1081/DRT-200059142