Composition comprising i) 15-95 wt% of an amide compound, ii) 5-75 wt% of a urea compound, iii) 0-50 wt% of an ionogenic compound, and iv) 0-35 wt% of an organic solvent, where the amide compound has a molar mass of 70 to 600 g/mol, the amide compound contains not more than one amide group with hydrogen bonded to its nitrogen atom, the amide compound has no urea group, no phosphorus, no silicon, and no halogen, and the amide compound is present in accordance with the general formula, where Xx is identical or different and is represented by an amide group C(=O)-N which is linked to Rz, Ra, and Rb in accordance with one of the general formulae RzC(=O)-NRaRb, RaC(=O)-NRzRb, and RbC(=O)-NRzRa Xy is identical or different and is represented by an amide group C(=O)-N which is linked to Rz, Rc, and Rd in accordance with one of the general formulae RzC(=O)-NRcRd, RcC(=O)-NRzRd, and RdC(=O)-NRzRc Rz in each case is identical or different and is represented by a branched or unbranched, saturated or unsaturated hydrocarbon radical which has 1 to 32 carbon atoms and which as heteroatom-containing groups may contain exclusively amino and/or amide groups, Ra, Rb, Rc, and Rd, in each case identically or differently and in each case independently of one another, are represented by hydrogen and/or a branched or unbranched, saturated or unsaturated organic radical containing 1 to 16 carbon atoms, with the proviso that Ra, Rb, Rc, and Rd in their entirety have at least four carbon atoms, not more than one of the radicals from the group of Ra, Rb, Rc, and Rd is present in the form of hydrogen, Ra and Rb and/or Rc with Rd, together with the CO-N moiety joining Ra to Rb and/or Rc to Rd, may together, in accordance with the general formula ( α-1), form a cyclic structure having 4 to 10 ring atoms, and/or Ra and Rb and/or Rc with Rd, together with the N atom joining Ra to Rb and/or Rc to Rd, may together, in accordance with the general formula ( β-1), form a cyclic structure having 4 to 7 ring atoms, or Rb and Rc together with the N atom bonded to each of Rb and Rc, and also with the radical Rz, may, in accordance with the general formula ( γ - 1), form a cyclic structure having 5 to 7 ring atoms Ra, Rb, Rc, Rd, and Rz in their entirety have not more than 36 carbon atoms and also not more than 8 heteroatoms from the group of N and O, the urea compound has a molecular weight of at least 350 g/mol and at least one urea group, the ionogenic compound contains a cationic component and an anionic component and is different from the amide compound and from the urea compound, and the organic solvent contains no urea group and no ionic group and also has not more than two heteroatoms selected from the group consisting of nitrogen and oxygen. i) 15-95 wt% of an amide compound, ii) 5-75 wt% of a urea compound, iii) 0-50 wt% of an ionogenic compound, and iv) 0-35 wt% of an organic solvent, Xx is identical or different and is represented by an amide group C(=O)-N which is linked to Rz, Ra, and Rb in accordance with one of the general formulae RzC(=O)-NRaRb, RaC(=O)-NRzRb, and RbC(=O)-NRzRa Xy is identical or different and is represented by an amide group C(=O)-N which is linked to Rz, Rc, and Rd in accordance with one of the general formulae RzC(=O)-NRcRd, RcC(=O)-NRzRd, and RdC(=O)-NRzRc Rz in each case is identical or different and is represented by a branched or unbranched, saturated or unsaturated hydrocarbon radical which has 1 to 32 carbon atoms and which as heteroatom-containing groups may contain exclusively amino and/or amide groups, Ra, Rb, Rc, and Rd, in each case identically or differently and in each case independently of one another, are represented by hydrogen and/or a branched or unbranched, saturated or unsaturated organic radical containing 1 to 16 carbon atoms, with the proviso that Ra, Rb, Rc, and Rd in their entirety have at least four carbon atoms, not more than one of the radicals from the group of Ra, Rb, Rc, and Rd is present in the form of hydrogen, Ra and Rb and/or Rc with Rd, together with the CO-N moiety joining Ra to Rb and/or Rc to Rd, may together, in accordance with the general formula ( α-1), form a cyclic structure having 4 to 10 ring atoms, and/or Ra and Rb and/or Rc with Rd, together with the N atom joining Ra to Rb and/or Rc to Rd, may together, in accordance with the general formula ( β-1), form a cyclic structure having 4 to 7 ring atoms, or Rb and Rc together with the N atom bonded to each of Rb and Rc, and also with the radical Rz, may, in accordance with the general formula ( γ - 1), form a cyclic structure having 5 to 7 ring atoms Ra, Rb, Rc, Rd, and Rz in their entirety have not more than 36 carbon atoms and also not more than 8 heteroatoms from the group of N and O, the urea compound has a molecular weight of at least 350 g/mol and at least one urea group, the ionogenic compound contains a cationic component and an anionic component and is different from the amide compound and from the urea compound, and the organic solvent contains no urea group and no ionic group and also has not more than two heteroatoms selected from the group consisting of nitrogen and oxygen.