A self-contained, portable wood treating apparatus and method for treating wood is disclosed. The wood treating apparatus includes a generally flat base in which a water tank is contained. A cylindrical pressure vessel is located above the base. A pair of elongate work tanks are located on respective sides of the pressure vessel between the pressure vessel and base. A reagent tank is also provided adjacent the base in which a concentrated treatment liquid is contained. A treatment system is provided for treating the wood located in the pressure vessel with a dilute treatment liquid contained in the work tanks. The treatment system includes a make up system for making up additional dilute treatment liquid by mixing water from the water tank and concentrated treatment liquid from the reagent tank. The improved method of operation includes the forming of dilute treatment liquid which is pumped into the pressure vessel to pressurize the pressure vessel and wood therein. This method also includes the steps of: pumping a diluent to the pressure vessel to pressurize the pressure vessel where the pumped flow rate of the diluent decreases as the pressure increases in the pressure vessel, measuring the flow rate of the pumped diluent, and adding concentrated reagent to the diluent being pumped in a varying proportional amount corresponding to the measured flow rate to form the proper concentration of dilute treating liquid in the pressure vessel.

A method for impregnating wood, wherein the wood (1) is placed in an airtight impregnation tank (2) from which the air has been evacuated, and which is subjected to pressure after the introduction of the impregnating liquid (17). The impregnating liquid is introduced under completely airtight conditions, whereby the liquid (17) is devoid of gas and air when impregnation takes place. An apparatus for carrying out the method comprises an impregnation tank (2) for containing the wood (1), wherein the tank is provided with pipes connecting it to a storage tank (11) containing impregnating liquid (17) for supplying the liquid to the impregnation tank. In connection with the impregnation tank (2) and the storage tank (11), equipment for evacuating the air or other gas from the tanks, from the wood and from the impregnating liquid (17). In connection with the impregnation tank (2) equipment is provided for increasing the pressure in the tank, e.g. by reducing the volume of the impregnation tank or by introducing additional liquid by means of a pressure pump.

Accelerated fixing of chromate-containing wood preservative salts, in which freshly impregnated timbers are subjected to fixing with superheated steam, is carried out by a process wherein the freshly impregnated timbers are subjected beforehand to a heat treatment in which both the wood surface and the internal walls of the heating chamber are heated to 60.degree.-100.degree. C., preferably 80.degree.-95.degree. C., and the timbers are then treated with superheated steam in a conventional manner.

Described is a method of treating wood with compositions comprising aqueous solutions of one or more lanthanide derivatives, whereby the composition is contacted with the wood under vacuum.

A wood treatment process is disclosed in which in one aspect the wood is impregnated with a waterborne preservative such as CCA at elevated temperature and pressure. The impregnated wood and excess waterborne preservative are separated while the treatment vessel (8) is pressurized, for example by blowing the preservative out of the vessel at the treatment pressure using a pump (10). Kickback may be segregated from the wood once pressure is reduced after the separation of wood and preservative. In another aspect the wood is impregnated with a waterborne preservative and with oil, each of the impregnating steps being performed under pressure and the oil being heated. If the preservative is one such as CCA which is capable of being fixed to the wood the hot oil may enhance this as well as providing water repellency. The oil may be a process oil.