Abstract: In a method of treating a raw wood material with a formaldehyde polymer in the presence of sulfur dioxide at a reaction temperature within a reaction vessel to obtain a modified wood material, sulfur dioxide is supplied into the reaction vessel when a gas pressure of the formaldehyde polymer within the reaction vessel is 4.00.times.10.sup.4 Pa or more. In addition, a concentration of the formaldehyde polymer is in a range of 30 to 350 mol/m.sup.3 of formaldehyde monomer, and a molar ratio of the formaldehyde polymer to sulfur dioxide is in a range of 10 to 350. As the formaldehyde polymer, for example, trioxane, tetraoxane, or paraformaldehyde is used. The modified wood material manufactured by the method including the above conditions shows excellent dimensional stability while a discoloration thereof is effectively prevented. Therefore, the modified wood material is particularly fit to use for an interior furniture, musical instrument and a bath tub, etc.

Abstract: A surface treatment process for improving surface properties of a timber as to wetness by exposing the timber to a plasma mixture of an inert gas and a reactive gas at a near atmospheric pressure. Prior to being exposed to the plasma mixture, the timber is treated to reduce a moisture content below a fiber saturation point of the timber so as to eliminate free moisture from the fibers of the timber which would otherwise lead to unstable plasma and therefore detract an uniform improvement over substantially the entire surface expected at the subsequent exposure to the plasma mixture. Thus, the plasma treatment can be effected in the absence of the free moisture to obtain a desired surface improvement uniformly across the surface of the timber, which gives an enhanced practicability of improving the surface properties of the timber, in addition to that the plasma mixture is generated at near the atmospheric pressures readily available without requiring substantial vacuum generating equipments.

Abstract: A method of manufacturing a modifed wood material can fix within a raw wood material an insoluble, non-flammable inorganic compound with a highly efficient reaction achieved between cations and anions by sequentially immersing the raw wood material at least three times alternately in each of, and different one from that employed immediately before of a first water-soluble inorganic substance solution containing cations and a second water-soluble inorganic substance solution containing anions.