A method of making a coatable composition includes: a) providing a initial composition comprising silica nanoparticles dispersed in an aqueous liquid medium, wherein the silica nanoparticles have a particle size distribution with an average particle size of less than or equal to 100 nanometers, and wherein the silica sol has a pH greater than 6; b) acidifying the initial composition to a pH of less than or equal to 4 using inorganic acid to provide an acidified composition; and c) dissolving at least one metal compound in the acidified composition to provide a coatable composition. The at least one metal compound includes at least one of a silver compound, a zinc compound, and a copper compound. Coatable compositions, antimicrobial compositions, preparable by the method are also disclosed. Antimicrobial articles including the antimicrobial compositions are also disclosed.