There is provided a composition comprising (a) at least one aqueous polymer dispersion, wherein said polymer is formed from a monomer mix comprising one or more carboxylic acid functional monomers; (b) at least one swelling agent; and (c) at least one polyvalent metal ion; wherein said composition is formed by a process comprising the step of forming a preliminary admixture of said dispersion (a) with some or all of said swelling agent (b), wherein the ratio of equivalents of polyvalent metal ions in said preliminary admixture to equivalents of carboxylic acid functional groups in said preliminary admixture is 0.25 or less.