A method for making modified latex particles, wherein the particles comprise condensation polymers bonded to functional groups on the latex particles and the method for forming the condensation polymer comprises reacting the amino groups present on the latex particles with (i) at least a first polyfunctional compound, having at least two functional moieties reactive with said functional groups of the latex, or (ii) at least a first polyfunctional compound, having at least two functional moieties reactive with said functional groups of the latex and at least a first amine compound, comprising amino groups selected from the group consisting of ammonia, a primary and a secondary amine to form a first condensation polymer reaction product comprising ion exchanging sites and a first unreacted excess of functional moieties.