Abstract: A process for darkening wood and thereby enhancing its surface characteristics is disclosed wherein wet wood is dried to about 6 percent moisture content in steam generated from the wood itself at temperatures from 215.degree. to 320.degree. F. and pressures from 15 to 40 psi whereby the wood is darkened through its thickness and thereby making the differentiation between earlywood and latewood in the wood more clearly observable than in wood not processed by this method and, thus, improves the wood grain quality.

Abstract: A process and apparatus for accelerated drying of green and partially dried lumber at pressures above atmospheric pressure to rapidly remove selected portions of moisture from the wood without degradation of the wood structure. A kiln for performing the method comprises a generally cylindrical kiln chamber to contain a stack of lumber, a by-pass line from the front to the back of the chamber to heat and distribute steam evenly to the lumber surfaces, a pressure-controlled steam vent to regulate kiln temperature, and temperature control to regulate the rate of drying. Conditions of pressure and temperature in the kiln can be regulated by heat added from an external source to equalize and condition the lumber rapidly in steam.