Abstract: A method of treating wood to provide anti-stain and anti-decay waterproofing properties includes applying to the wood a water solution having about 1.3 to 2.75 weight percent of a quaternary ammonium compound, about 1 to 2 weight percent of a hydrated starch solution, about 2.5 to 5.0 weight percent of a slack wax water emulsion and about 90 to 95 weight percent water. The solution may be created by establishing a first mixture of hydrated starch solution, slack wax emulsion and water and subsequently admixing the quaternary ammonium compound with a first mixture. Preferred solid concentrations of the emulsions are provided. A wood waterproofing composition contains about 1.3 to 2.75 weight percent of a quaternary ammonium compound, about 1 to 2 weight percent of a hydrated starch solution, about 2.5 to 5.0 weight percent of a slack wax emulsion and about 93 to 97.5 weight percent water.