Leaching is a crucial step in production of polymeric biomaterials since it removes initiator, accelerator, solvents, unreacted monomer, oligomer and other byproducts remaining after polymerization; such small molecules are generally acknowledged to be a major reason for biological reaction to implanted polymers. This paper shows that the ionizable groups common to some classes of hydrogels can be manipulated to greatly enhance the leaching process over common methods wherein the outer water bath is periodically changed. The method uses organic cosolvents and inorganic salts to control the swelling during the leaching process.