A product H that can be used as crosslinking agent which comprises a mixture of reaction products P of cyclic alkyleneureas U and multifunctional aldehydes A2 with further reaction products having as constituents, besides U and A2, also at least one of aminoplast formers M which are different from the cyclic alkyleneureas U, and of monofunctional aldehydes A1, the mixture constituting product H comprising the reaction products P made by reacting cyclic alkylene ureas U and multifunctional aldehydes A2, and at least one of the following reaction products: a) reaction products UMA2 made by reaction of cyclic alkylene ureas U, aminoplast formers M which are different from the cyclic alkyleneureas U, and multifunctional aldehydes A2 b) reaction products UMA1A2 made by reaction of cyclic alkylene ureas U, aminoplast formers M which are different from the cyclic alkyleneureas U, monofunctional aldehydes A1, and multifunctional aldehydes A2 c) reaction products MA1A2 made by reaction of aminoplast formers M which are different from the cyclic alkyleneureas U, monofunctional aldehydes A1, and multifunctional aldehydes A2 d) reaction products UA1A2 made by reaction of cyclic alkylene ureas U, monofunctional aldehydes A1, and multifunctional aldehydes A2 e) reaction products MA2 made by reaction of aminoplast formers M which are different from the cyclic alkyleneureas U, and multifunctional aldehydes A2 f) reaction products UA1 made by reaction of cyclic alkylene ureas U, and monofunctional aldehydes A1 g) reaction products UMA1 made by reaction of cyclic alkylene ureas U, aminoplast formers M which are different from the cyclic alkyleneureas U, and monofunctional aldehydes A1 h) reaction products MA1 made by reaction of aminoplast formers M which are different from the cyclic alkyleneureas U, and monofunctional aldehydes A1 wherein, in the case of reaction product h) being present in mixture with the reaction product P which is UA2, at least one of the other reaction products a), b), c), d), e), f), or g) is also present in the mixture, and wherein product H or reaction product P of U and A2, or both are optionally etherified by reaction of at least a part of the hydroxyl groups formed by addition reaction of N-H groups and aldehyde groups, with one or more aliphatic alcohols R'-OH having preferably from one to ten carbon atoms, and which alcohol R'-OH may be linear, branched or cyclic, wherein glyoxal is present in the at least one multifunctional aldehyde A2, wherein the multifunctional aldehydes A2 obey the formula OHC-R"-CHO where R" may be a direct bond or a divalent radical which may preferably be a linear, branched or cyclic aliphatic divalent radical and may have from one to forty carbon atoms, or an aliphatic divalent radical which may be linear, branched or cyclic and may have from one to thirty-nine carbon atoms, which radical carries at least one additional aldehyde group -CHO and wherein the cyclic alkylene ureas U have at least one unsubstituted amidic >NH group and are cycloaliphatic or bicycloaliphatic compounds having an element of the structure -NH-CO-NH-within an aliphatic ring structure, the total number of ring atoms preferably being from 5 to 7. a) reaction products UMA2 made by reaction of cyclic alkylene ureas U, aminoplast formers M which are different from the cyclic alkyleneureas U, and multifunctional aldehydes A2 b) reaction products UMA1A2 made by reaction of cyclic alkylene ureas U, aminoplast formers M which are different from the cyclic alkyleneureas U, monofunctional aldehydes A1, and multifunctional aldehydes A2 c) reaction products MA1A2 made by reaction of aminoplast formers M which are different from the cyclic alkyleneureas U, monofunctional aldehydes A1, and multifunctional aldehydes A2 d) reaction products UA1A2 made by reaction of cyclic alkylene ureas U, monofunctional aldehydes A1, and multifunctional aldehydes A2 e) reaction products MA2 made by reaction of aminoplast formers M which are different from the cyclic alkyleneureas U, and multifunctional aldehydes A2 f) reaction products UA1 made by reaction of cyclic alkylene ureas U, and monofunctional aldehydes A1 g) reaction products UMA1 made by reaction of cyclic alkylene ureas U, aminoplast formers M which are different from the cyclic alkyleneureas U, and monofunctional aldehydes A1 h) reaction products MA1 made by reaction of aminoplast formers M which are different from the cyclic alkyleneureas U, and monofunctional aldehydes A1