Abstract - 587127 Disclosed herein is a method of preparing a composition comprising sub-micron particles, containing or coated with an active agent(s), the method comprising at least the steps of: (i) dispersing sub-micron particles of natural or synthetic organic or inorganic clay in a solvent(s) (ii) adding to the dispersion, a formulation containing the active agent(s) dissolved in a suitable solvent in a manner sufficient to achieve substantial uniformity of the mixture (or vice versa) or dispersing sub-micron particles of natural or synthetic organic or inorganic clay in a solvent(s) whilst concurrently or sequentially dissolving an active agent in said solvent in a manner sufficient to achieve substantial uniformity of the mixture and then altering the physicochemical environment within the dispersion to cause the active agent to fall out of solution as a sub-micron layer in or on the sub-micron particles wherein the active agent is a biocide, colouring agent, water repellent agent or a mixture thereof.
