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Spiral grains are one of the most important tree growth defects that can remarkably affect the shape stability of lumber. This growth defect is observed by an oblique arrangement of axially oriented cell elements in the wood. This research focused on identifying and measuring selected shape changes caused by the spiral grains in the log. Hornbeam logs with spiral grain and with no spiral grain aged 60 and 52 years were selected to detect shape changes. Following the research and the norms of STN EN 1309-3 (49 1013), DIN (4074-5), and ASTM D245, it can be stated that spiral grain is an essential factor affecting the shape stability of hornbeam lumber. In the case of lumber with spiral grain, the spiral grain increased by up to 8° within three months. The warp of both types (bow, crook) increased exponentially throughout the study, peaking between the third and fourth week with an increase in warp bow of 26 mm and 17 mm in warp crook. [ABSTRACT FROM AUTHOR]

The article presents the impact of drying process and selected parameters on the color changes on the surface of pine wood (Pinus sylvestris L.). Three predetermined process conditions (modes), mild, normal, and intensive, were investigated. The experiments were conducted using a semi-industrial scale dryer designed at the Gdańsk University of Technology with a loading capacity of 0.55 m3. The drying process was applied to pine wood grown in the northern part of Pomeranian region in Poland. The specimens were selected taking into consideration the radial angle of the growth rings. During each drying mode, 25 pieces of wood with dimensions (thickness, width, length) of 0.03 m, 0.2 m, and 1.5 m, respectively, were dried. The total color change (E) after drying process and color saturation (h*) before and after drying processes of the wood surface was determined using the normalized CIELAB methods. The obtained results indicated that the color change of the pine wood surface increased simultaneously with the intensification of the drying process. However, the normalized wood quality after drying under intensive drying process conditions remained within the standard limits. The application of intensive drying process conditions remarkably changes the surface color of the obtained material, while remarkably reducing the drying process duration. [ABSTRACT FROM AUTHOR]

This study focused on the impact of the wood sawing pattern on 50 mm thick beech timber, followed by cross-cutting on the 3 m long, 50 x 50 mm beech blanks. The study analyzed two methods of cutting patterns of beech blanks (parallel to the surface of the timber and parallel to the grain fiber of the timber) regarding yield values and the size of longitudinal warping after air-drying. The yield values were higher (from 65.14 to 72.70 %) when producing long beech blanks using the method of sawing parallel to the timber's axis (B) compared to parallel to the edge of the blank (from 60.38 to 68.40 %). Results showed that a crucial factor for choosing the cutting method (A or B) is the taper of the logs. For blanks with a taper ≥ 1.3 cm.m-1, it is more advantageous in terms of longitudinal warping and yield to use the method of sawing parallel to the timber's axis. [ABSTRACT FROM AUTHOR]