Compositions and methods for treating cellulose-based materials with micronized additives

Wood treated by a process comprising the steps of:

• a) providing an aqueous composition comprising one or more solid particles of a first additive and a second additive dispersed in water, said particles having diameters in the range of 0.001 to 25 microns;
• and
• b) applying said composition to the wood such that at least some of the particles penetrate the surface of the wood and are distributed throughout a cross section of the wood;
• wherein the first additive is carbon black or black iron oxide;
• greater than 80 weight percent of the particles of the first additive have diameters less than 1 micron;
• and the second additive is zinc oxide, titanium dioxide, or an aluminum flake pigment;
• wherein the first and second additives are applied to the wood by pressure treatment, vacuum treatment, or both;
• and
• wherein the wood comprises solid particles of the first and second additives inside the wood.