Determination of color-changing effects of bleaching chemicals on some heat-treated woods

The aim of this study was to use bleaching chemicals to remove the discoloration occurring on the surface of wood after heat treatment in order to restore the natural color of the wood. For this purpose, samples prepared from Scots pine (Pinus sylvestrisL.), sessile oak (Quercus petraeaL.), Eastern beech (Fagus orientalisL.), and Uludag fir (Abies bornmuellerianaMattf.) were exposed to heat treatment at temperatures of 140 and 160 degrees C for time periods of 3, 5, and 7 h. Bleaching solutions S1 (NaOH + H2O2), S2 (NaSiO3 + H2O2), and S3 (H2C2O4) at a concentration of 18% were then applied to the surface of the materials and the color change was determined according to ASTM D 2244 standard. Depending on the heat treatment temperature and duration, an increase in total color change values was detected on the surfaces of the materials and the color of the samples became darker. The total color change values decreased after bleaching with the S2 solution in the heat-treated Scots pine and fir samples, with the S3 solution in the beech samples, and with the S1, S2, and S3 solutions in the oak samples. The findings showed that by using bleaching chemicals to lighten wood materials darkened after heat treatment, it is possible to obtain results close to the natural color values.WOS:0005769787000022-s2.0-8509172306

Effects of Thermo-Vibro-Mechanic (R) Densification on the Density and Swelling of Pre-Treated Uludag Fir and Black Poplar Wood

The radial and tangential swelling as well as the fully dried density of low-density wood materials densified via the Thermo-Vibro-Mechanic (R) method were evaluated in response to applying wood stain and preservative. The samples obtained from Uludag fir (Abies bornmuelleriana Mattf.) and black poplar (Populus nigra L.) in the radial and tangential direction were pre-treated with wood stain and preservative before undergoing Thermo-Vibro-Mechanic (R) densification. Thermo-Vibro-Mechanic (R) densification was performed at three different temperatures (100 degrees C +/- 3 degrees C, 120 degrees C +/- 3 degrees C, and 140 degrees C +/- 3 degrees C), three different vibration pressures (0.60 MPa, 1.00 MPa, and 1.40 MPa), and three different vibration times (20 s, 60 s, and 100 s). Afterwards, changes in the fully dried density and swelling amounts in the radial and tangential directions of the samples were determined. The fully dried density increased by 15.4% to 38% and the radial and tangential swelling amounts increased by 73.2% to 242.6%, when the densified samples were compared to the control samples. In general, the fully dried density and swelling values increased depending on the Thermo-Vibro-Mechanic (R) densification parameters; higher values were found as the compression ratio and total application time increased.[115O138]This research has been written in memory of Dr. Suleyman Senol, who passed away on May 10, 2019. The study was supported by Project No. 115O138 within the scope of the TUBITAK-3001 Start R&D Projects Support Program. In addition, the ThermoVibro-Mechanic (R) (TVM) trademark was registered on July 01, 2019 (Trademark No. 2018/120796), and Thermo-Vibro-Mechanic (R) Density Press Machine patent was registered on December 21, 2020 (Patent No. TR 2019 01054 B) by the Turkish Patent and Trademark Authority.WOS:00063469690003

Surface Roughness of Thermally Treated Wood Cut with Different Parameters in CNC Router Machine

The effects of different machining parameters on surface roughness values of thermally treated pine, beech, and linden woods cut in a computer numerical control (CNC) router machine were examined. Wood specimens were thermally treated at 170, 190, and 210 degrees C for 2 h. Then, specimens were cut in the radial and tangential directions with three different spindle speeds (12000, 15000, and 18000 rpm) and three different feed rates (3000, 4000, and 6000 mm/min) using two different end mill tools (spiral and straight) on the CNC machine. The end mill type significantly affected the roughness values of the untreated and thermally treated specimens in both directions. Lower roughness values were found in the specimens (especially pine) machined with the straight end mill compared to those machined with the spiral end mill. Roughness generally decreased in the thermally treated specimens. However, thermal treatment temperature did not have a notable effect on roughness. As the spindle speed increased, the roughness values of all specimens decreased. In contrast, as the feed rate increased, the roughness values increased. Therefore, the end mill type, feed rate, and spindle speed were the most influential parameters on the roughness.Research Fund of Duzce UniversityDuzce University [BAP-2018.07.01.742]The authors are grateful for the support of the Research Fund of Duzce University, Grant No. BAP-2018.07.01.742.WOS:00068834260002

Antitermitic effects of three wood stain treatments

Potential antitermitic properties of some common wood stains were tested against Coptotermes formosanus. Four different wood species treated with 3 different stain chemicals at the 0,1 kg/m2 retention level were exposed to no-choice termite feeding test in laboratory conditions. Mean mass loses, mortality rates and consumption rates were calculated based on weight changes before and after the test. While the hardwood species (beech (Fagus orientalis) and chestnut (Castanea sativa) tested were unaffected by the treatments, the softwood species tested showed drastically reduced mass losses with some stain treatments. Scots pine (Pinus sylvestris) and spruce (Picea orientalis) sapwood exhibited significant reductions in mass losses when treated with the chemical stain

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

One of the most persistent problems with mechanically densified wood is its inherent dimensional instability. The effects of heat post-treatment on the changes in spring-back (SB), compression ratio recovery (CRR), thickness swelling (TS), and water absorption (WA) of newly-tested Uludag fir (Abies bornmuelleriana Mattf.) and black poplar (Populus nigra L.) wood samples that had been thermo-mechanically densified were investigated. Samples were densified with compression ratios of 25\% and 50\% with temperatures of 100 and 140 degrees C, respectively. Then, the heat post-treatment was applied to the samples at 185 and 212 degrees C for 2 h. For the two newly-tested wood types, results of the preliminary study show that SB and TS were higher at a 50\% compression ratio compared with 25\%. Regarding densification temperature, TS was lower in samples densified at 140 degrees C, while SB was higher. WA values were lower in compressed samples (50\%) at high rates. The effect of the densification temperature on WA was insignificant. Heat post-treatment had a considerable effect on the dimensional stability and hygroscopicity of the densified Uludag fir and black poplar samples. With an increase in heat treatment temperature, the dimensional stability increased, while the hygroscopicity of densified samples decreased. As a result of heat post-treatment applied at 212 degrees C, SB, CRR, TS, and WA decreased by 88\%, 85\%, 79\%, and 53\%, respectively

Effects of Thermomechanical Densification and Heat Treatment on Density and Brinell Hardness of Scots Pine (Pinus sylvestris L.) and Eastern Beech (Fagus orientalis L.)

The effects of thermomechanical densification (TMD) and heat treatment on density and Brinell hardness of Scots pine (Pinus sylvestris L.) and Eastern beech (Fagus orientalis L.) woods were investigated. Samples were densified using a specially designed hydraulic press with target compression ratios of 20 and 40\%, and at 110 degrees C and 150 degrees C. Then, the heat treatment was applied to the samples at three different temperatures. To determine whether the changes occurred because of technological properties, tests of Brinell hardness and air-dry density were conducted. Increases of 42 and 35\% were obtained for the density of Scots pine and beech samples, respectively. After the densification process, increases in radial and tangential hardness values were obtained. Decreases were observed in the density and hardness values of the samples because of the increase in temperature during heat treatment. After heat treatment, there were 4 and 5\% decreases in the respective densities of Scots pine and beech, and decreases in their radial and tangential hardness values

The Effects of Densification and Heat Post-Treatment on Hardness and Morphological Properties of Wood Materials

This study investigated the effects of densification and heat post-treatment on the Janka hardness and microscopic structure of relatively low-density Uludag fir, linden, and black poplar woods. Wood samples were densified with compression ratios of 25\% and 50\% at 100 degrees C and 140 degrees C, respectively. Heat post-treatment was then applied to the samples at 185 degrees C and 212 degrees C for 2 h. The hardness in the radial and tangential directions was determined, and morphological changes in the cell structures were analyzed using scanning electron microscopy (SEM). The hardness values in the radial and tangential directions of the densified samples increased depending on the compression rate and treatment temperature. The hardness values in both directions were higher in the 50\% compressed samples. For samples compressed at 140 degrees C, the hardness values were higher in the tangential direction, whereas the samples compressed at 100 degrees C were higher in the radial direction. After the heat post-treatment process, the hardness values of all samples decreased. As the treatment temperature increased, more adverse effects on the hardness was noted. According to the SEM analyses, the densification and heat post-treatment deteriorated the cell structure of the samples. The more cell deformation was observed in the samples densified at 100 degrees C with compression ratio 50\% and high heat post-treatment temperature