What is described herein is an aqueous dispersion for coating water-soluble granules of a water soluble active agricultural chemical to substantially increase the rain fastness of the active. The dispersion includes by wt.

• (a) at least 0.1% of a polymeric anionic dispersing agent,
• (b) 5-30% of a water-insoluble, natural or synthetic inorganic or organic polymer, and
• (c) to 100% of water.