Disclosed is a method of preparing compositions comprising submicron particlesof a metal salt. The method comprisesproviding an aqueous alkaline solution comprising a metal, one or more ligandthat forms a soluble complex with the metal underalkaline conditions, and optionally one or more dispersant； and admixing thesolution and a source of carbon dioxide to reduce the pHof the solution such that submicron particles of a metal salt precipitate.Also disclosed are compositions prepared by the method. Alsodisclosed is a method of treating a substrate, such as lumber, comprisingapplying the compositions and substrates treated by the method.
