Improvement of Liquid Penetration of Wood by Precompression method

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A new system for enhancing the penetration of liquid into wood using a precompression treatment was designed, and the effects of the many factors on the liquid uptake were evaluated. Results obtained are as follows :1) Precompression of up to 60% under appropriate moisture and heat conditions effectively increased the penetration of liquid into refractory wood samples of practical sizes without producing any strength reduction.2) Set-recovered wood in which loading was released immediately after precompression, and preset-fixed wood which was dried under the influence of a decompression force. The amount of liquid takes up by set-recovered wood was 2-3 times that taken up by untreated wood. When preset-fixed wood was dipped in liquid and the deforming force was released, liquid penetration was more than 25 times that seen in untreated softwood heartwood. Liquid effectively penetrated even long samples when pressure impregnation was applied to precompressed and preset-fixed wood.3) No s … More ignificant reduction of strength was observed for treated wood. Fracture of pit membranes during compression with little damage to unpitted cell-walls and an elastic recovery process were believed to improve liquid penetration with negligible compression defects.4) Precompression up to 50% deformation under the different condition of moisture content of specimen (dry or wet) and ambient temperature (room-temperature, 30ﾟC or 80ﾟC) effectively increased the liquid uptake differed within wood species even when the same level of compressive deformation was applied. The maximum amount of liquid uptake was recognized when precompressed under the wet condition at 30ﾟC for Douglus-fir (Beimatsu) and 80C for Japanese cedar (Sugi), but no significant difference was observed among the treatment condition for Japanese cypress (Hinoki) and Japanese larix (Karamatsu).5) The liquid uptake increased in dye-solutions, which varied upon the precompression conditions of specimens and ambient temperature.6) SEM observations visualized the opening of the enclosed bordered pits for softwood and the fracture of tyloses in the vessel for hardwood due to precompression treatment, as a result the liquid penetration was remarkably improved for refractory wood. Less