The aim of this study was to investigate effects of natural weathering on color stability of Scots pine (Pinus sylvestrisL.) and Oriental beech (Fagus orientalisL.) impregnated with some chemicals [tanalith-E (TN-E), adolit-KD5 (AD-KD5), and chromated copper arsenate (CCA)] and then varnished [synthetic varnish (SV) and polyurethane varnish (PV)]. While applying varnish increased lightness, impregnation decreased lightness of the wood specimens before natural weathering. Natural weathering caused greenish, bluish, and dark color tones of the wood surface. Total color change was increased with increasing exposure times in natural weathering. Untreated (control) wood specimens exhibited higher color changes than the other wood specimens in all the stages of natural weathering. The total color changes of untreated Oriental beech specimens were less than untreated Scots pine specimens. The color stability of impregnated and varnished wood specimens gave better results than untreated and solely varnished wood specimens after natural weathering. The best color stability was obtained from both Oriental beech and Scots pine wood impregnated with TN-E before PV coating.

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Wood is widely used as a construction material for many applications. To have knowledge about the thermal degradation characteristic of wood could be crucial for indoor and outdoor applications. Chemical treatments could improve the resistance of wood against fire and heat. In this study, to investigate the thermal properties of Oriental beech (Fagus orientalis) wood treated with 0,25%; 1% and 4,70% aqueous solutions of boric acid, borax, disodium octaborate tetrahydrate and mixtures of and in different proportions, thermogravimetric analysis, differential-thermogravimetry, and differentialthermal analysis were performed.Our results showed that borate treatment decreased the T max (maximum degradation temperature) and increased residual char amount. Higher concentration levels of borates resulted in higher char content of Oriental beech wood specimens. Residual char content of borate treated wood samples at fixed concentration of 4,70% ranked as in the following order: disodium octaborate tetrahydrate > boric acid + borax (7:3) > boric acid + borax (1:1) > boric acid > borax >Control. The highest residual char content was achieved for the sample impregnated with 4,70% disodium octaborate tetrahydrate among the all treated samples.

Heat treatment of Oriental-beech (Fagus orientalis) wood was carried out by hot air in an oven for 2, 4, and 8 h at 140, 170, and 200°C. After heat treatment, some physical characteristics such as surface roughness, color, glossiness, and mass loss of Oriental-beech wood specimens were measured.Our results showed that heat treatment caused decrease in surface roughness, glossiness, and mass loss values of Oriental-beech (Fagus orientalis) wood specimens. The decrease in lightness at all temperatures indicates that the specimens become darker with the treatment time. While, a* coordinate (red component) decreased as temperature increased, b* coordinate (yellow component) initially increased at 140°C and then decreased at 170°C and 200°C.

In this study, investigation of the thermal properties of Oriental beech (Fagus orientalis) sawdust treated with 0,25; 1 and 4,70% aqueous solutions of Adolit KD-5, Wolmanit CX-8 and Tanalit-E were performed by using thermogravimetric analysis, differential-thermal analysis, and differential-thermal analysis under argon atmosphere.Results were compared with the untreated wood (control). It was found that the treatment with Adolit KD-5, Wolmanit CX-8 and Tanalit-E decreased the T max (maximum degradation temperature) and increased residual char amount with respect to the control sample. Increases in the concentration of applied preservatives promote the char formation. It was found that the char content after pyrolysis experiment had good agreement with the boric acid amount in wood preservatives.

This study investigated the thermal properties of Oriental beech (Fagus orientalis) treated with (NH 4) 2 H-PO 4 , K 2 HPO 4 , NH 4 Cl and (NH 4) 2 SO 4 salts and their mixtures (1:1; w/w) aqueous solutions at 3% concentrations. The effects of different inorganic salts fire retardants on the thermal degradation characteristics of wood samples were evaluated by thermogravimetric analysis (TGA). Based on the TGA curve for untreated beech wood, weight loss takes place at three distinct steps. The impregnation of inorganic salts resulted in higher char yields and additional thermal degradation steps were identified. The highest char yield (80%) was obtained from (NH 4) 2 HPO 4-K 2 HPO 4 mixture impregnated sample. Salt mixtures containing phosphates ((NH 4) 2 HPO 4 and K 2 HPO 4) have remarkable effects on thermal stability of beech wood, whereas NH 4 Cl salt lowered the decomposition temperatures and char yield.