An aqueous radiation curable composition (I) comprising : - at least one ethylenically unsaturated polyurethane (A) obtained from the reaction of at least one polyisocyanate compound (Ai); at least one ethylenically unsaturated compound (Aii) containing at least one reactive group capable to react with isocyanate groups; at least one hydrophilic compound (Aiii) containing at least one reactive group capable to react with isocyanate groups and at least one other group which is capable to render the polyurethane polymer dispersible in aqueous medium as such or after the formation of a salt; and, optionally, at least one polyol (Aiv); said ethylenically usaturated polyurethane (A) being characterized by a weight average molecular weight that is above 1,000 Daltons; - at least one ethylenically unsaturated polyurethane (B), different from the polyurethane (A), obtained from the reaction of at least one polyisocyanate compound (Bi); at least one ethylenically unsaturated compound (Bii) containing at least one reactive group capable to react with isocyanate groups; and, optionally, at least one polyol (Biv); said ethylenically unsaturated polyurethane (B) preferably being characterized by a molecular weight that is below 10,000 Daltons; and - optionally, at least one ethylenically unsaturated compound (C) different from (A) and (B); wherein the equivalent ratio of isocyanate-reactive groups provided by compounds (Aii) to isocyanate groups provided by compounds (Ai) is above 50% and at most 99%; and with the proviso that if polyols (Aiv) and/or (Biv) are used, (Aiv) are saturated polyols and (Biv) can be saturated polyols and/or unsaturated polyols; wherein the radiation curable composition (I) composition comprises, relative to the total weight of (A), (B) and (C), at least 2.5 wt% of compounds (B); and wherein the radiation curable composition (I) in dry form has a steady-state creep viscosity η 30 . expressed as the apparent viscosity after a deformation time of 30 minutes with a load σ0 = 50 Pa at 23°C, that is above 1.10 3 Pa.s, preferably is above 1.10 4 Pa.s. - at least one ethylenically unsaturated polyurethane (A) obtained from the reaction of at least one polyisocyanate compound (Ai); at least one ethylenically unsaturated compound (Aii) containing at least one reactive group capable to react with isocyanate groups; at least one hydrophilic compound (Aiii) containing at least one reactive group capable to react with isocyanate groups and at least one other group which is capable to render the polyurethane polymer dispersible in aqueous medium as such or after the formation of a salt; and, optionally, at least one polyol (Aiv); said ethylenically usaturated polyurethane (A) being characterized by a weight average molecular weight that is above 1,000 Daltons; - at least one ethylenically unsaturated polyurethane (B), different from the polyurethane (A), obtained from the reaction of at least one polyisocyanate compound (Bi); at least one ethylenically unsaturated compound (Bii) containing at least one reactive group capable to react with isocyanate groups; and, optionally, at least one polyol (Biv); said ethylenically unsaturated polyurethane (B) preferably being characterized by a molecular weight that is below 10,000 Daltons; and - optionally, at least one ethylenically unsaturated compound (C) different from (A) and (B); with the proviso that if polyols (Aiv) and/or (Biv) are used, (Aiv) are saturated polyols and (Biv) can be saturated polyols and/or unsaturated polyols; wherein the radiation curable composition (I) composition comprises, relative to the total weight of (A), (B) and (C), at least 2.5 wt% of compounds (B); and wherein the radiation curable composition (I) in dry form has a steady-state creep viscosity η 30 . expressed as the apparent viscosity after a deformation time of 30 minutes with a load σ0 = 50 Pa at 23°C, that is above 1.10 3 Pa.s, preferably is above 1.10 4 Pa.s. <EOS>