| The color parameters, were measured in six Paulownia species, which were Paulownia elongata from Gansu province, Paulownia tomentosa Steud from Hubei province, Paulownia fortunei from Hunan province, Paulownia elongata from Henan province, Paulownia catalpifolia and Paulownia Yulin from Shandong province. Evaluated the quality of wood color according to the different growth position and species. After the evaluation, the paulownia were rain treated under the natural condition to improve the wood color. Compared the change of color parameters and total phenol content on wood surface, studied the influence of rain treatment on paulownia wood color and further explored the relationship between the phenol content change and color change. Treated the paulownia by the water treatment and surface fire-induced discoloration treatment in single paulownia species. Compared the colour change before and after the two differet treatments, studied the influence, to get the best treatment process. Explored the new saving energy and protecting environment technology of improve the paulownia wood color.The main conclusions are as follow:1) The quality of wood colour in six paulownia species was: Paulownia fortunei > Paulownia catalpifolia > Paulownia elongata from Gansu province ≥ Paulownia Yulin > Paulownia elongata from Henan province > Paulownia tomentosa Steud. The difference of five color parameters in different paulownia species reached significant level. The color parameters change was consistent in the different stem position: the top of stem > the middle of stem ≥ the bottom of stem. In the disk, the difference between heart wood and sapwood was not significant in Paulownia fortunei. The heart wood of Paulownia elongata from Gansu province was better than that of sapwood while the sapwood of other four paulownia species were optimal. The difference of five color parameters in different growth position reached significant level.2) The quality of wood color of paulownia was improved after the rain treatment. The lightness increased, the value change ranged from 0.04 to 6.64. The general chromatism decreased, the value change ranged from 0.1 to 4.21. The whiteness was increased in the five paulownia species except the Paulownia fortune, the value change ranged from1.37 to 6.17. There was no consistent regular in red and yellow degree. The color of the Paulownia tomentosa Steud was greatest impact by the rain treatment and Paulownia fortune was the minimal impact by rain treatment. After the treatment the color parameters reached extremely significant level. The phenol content of the surface of six paulownia species reduced. There was a positively correlation between the value of color change and the phenol content change.3) The quality of wood color in paulownia improved by the water treatment. Optimal processing technology with setting the temperature to 60℃, pH=9, processing 18 days, and the frequency of change water was three days. The lightness increased 1.55, the amount of increase was 2.08%. The amount of increase was 4.9% in red degree and 2.46% in yellow degree. The value of general chromatism was reduced by 9.68%; The whiteness increased from 53.8 to 71.36, the amount of increase was 24.61%. After the water treatment all the color parameters were statistically significant in different group.4) The color of paulownia become darker after the surface fire-induced discoloration treatment. Optimal processing technology was the fire at the speed of 5cm/s, the distance of fire source is 3cm, deal with three times. After treatment the brightness was from 72.54 down to 40.54, drop of 44.04%. Red degrees increased from 4.98 to 6.71. Yellow degree is decreased from 18.4 down to 12.87, drop of 30.07%. The general chromatism decreased before treatment was 26.97, after the treatment was 4.98, drop of 81.52%. Whiteness was 60.82 before treatment, dropped to 49.43, a drop of 18.74%. After the treatment the color parameters reached a extremely significant. |
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