process for preparing a silver - containing , disperse , water - containing formulation useful for producing electrically conductive and / or optically reflective coatings , which comprises reacting a silver salt solution with a solution containing hydroxide ions , wherein at least one of said solutions comprises a polymeric dispersant , to produce an ag 2 o sol , reacting the ag 2 o sol obtained from step i ) with a reduction agent , and purifying the solution obtained from step ii ).