Modified open-cell foams and method for the production thereof Process for production of modified open-cell foams, which comprises bringing the following materials into contact (a) open-cell foams with density in the range from 5 to 500 kg/m.sup.3 and average pore diameter in the range from 1 .mu.m to 1 mm, and (b) aqueous formulation of at least one compound having at least one hemiaminal or aminal group per molecule, or at least one copolymer comprising at least one copolymerized OH-containing or .beta.-dicarbonyl-containing or epoxy-containing comonomer.