The effects of bleaching process on some wood species modified with thermal treatment

The aim of this study is to determine the effect to some heat ? treated woods of bleaching process. For this purpose, natural color, brightness and hardness values of woods - Scotch pine (Pinus sylvestris L.), Sessile oak (Quercus petraea L.), Eastern beech (Fagus orientalis L.), and fir (Abies bornmülleriana Mattf.) ? are to obtained by using variety of bleaching chemicals in order to measure some physical degradation occurred after heat treatment. The woods were exposed to heat treatment at different temperatures of 1400C and 1600C, and at different times periods for 3, 5, and 7 hours. Then S1 (NaOH + H2O2), S2 (NaSiO3 + H2O2) and S3 (H2C2O4) solutions at concentration of 18% were applied to the material surfaces in order to identify change values of color, brightness and, hardness according to ASTM D 2224, EN ISO 2813 and ASTM D 2240 standards. According to research result, the bleaching solutions used to heat-treated wood surfaces causes to decrease of color and brightness values but increase the hardness values. So, the result indicated that the application of the S1 and S2 solutions groups gave more closed to natural color, brightness and hardness values for the heat-treated wood surfaces.