The effects bleaching chemicals on the finishing processes of wood materials

In this study, the effects of bleaching process on the water spreading, macroscobic change and varnishing process for colur, brihtness and bonding strength of wood surface, which some of these wood species widely used inner and outer conditions (furniture, decoration, carpentry etc.) with or without impregnated material in Turkey have been analyzed. In addition, the effects of the solution groups on the weight lose, density, compression strength parellel to grain and bending strength, across to grain for oriental beech (Fagus orientalis Lipsky), oak (Quercus petraea spp.), chesnut (Castanea sativa Mill.), pine (Pinus sylvestris Lipsky ) which are mostly used in wooden industry in Turkey, have been studied. IR spectroscope was used to determine the effects of solution groups at the chemical structure of wood. The pressure method for impregnation process was applied by using Tanalith CBC(T-CBC) and Imersol WR 2000 (I-WR 2000) according to the procedure of ASTM-D- 1413-76 standards. Sodium hydroxide (NaOH), hydrogen peroxide (H202), calcium hydroxide (Ca(OH)2), sodium silicate (NaSi03), magnesium sulfate (MgS04), sodium bisulfide (NaHS03), potassium permanganate (KMn04), acetic acid (CH3COOH) and oxalic acid (H2C2O4) were used as a bleaching chemical. Water based polyurethane and synthetic varnishes were used for the varnishing of the wood samples. According to the research results, all of the solution groups decreased the yellow and red color tones and increased the degree of colur angle in both impregnated and unempregnated samples. When synthetic varnish was used on the T-CBC, the yellow color tone and synthetic varnish used was on the I-WR 2000 the red color tone are increased. In contrast, when water based varnish was used, these color tones decread. The results showed that, I. and II. groups have strong, III. and VI. groups have an average, IV. and VI. groups have weak effects on the bleaching characteristics. All of the solutions groups resulted in the decrasing in brightness and increasing the water spreading value on both the impregnated and unimpregnated wood samples. The effect of solution groups on brightness, water spreading are found to be unimportant, but^the effects of varnishes are important synthetic varnish since it gave the best brightness. The water spreading value was found to be higher on the unimpregnated wood samples. Water based varnish showed higher bonding strength. The difference between the water spreading values are found not to be important among the varnishes. Colur changing and fiber swelling are observed on wood sample after bleaching process under the macroscopic examination. Solution groups decrased the bending strength as 10 %, compression strength as 9 %, and density as 6 %. According to the IR spectroscope, O-H peak was vanished or decrased in the I. and II. groups bleached samples and some of the peaks moved to another place. Science code : 6001013 Key Words :Wood, Bleaching, Finishing, IR spectroscope, Impregnation, strength characteristics