A cosmetic agent for treating a keratinous material, comprising a) at least one organosilicon compound and b) at least one strengthening copolymer, which is made up of at least the following monomer units: - N-tert-octylacrylamide, - acrylic acid, and - tert-butylaminoethyl methacrylate and the INCI name "Octylacrylamide/Acrylates/Butylaminoethyl Methacrylate Copolymer," characterized in that the agent for treating a keratinous material contains, based on the total weight of the agent for treating a keratinous material: - 0.5 to 3.0 wt.% of at least one first organosilicon compound selected from the group consisting of (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, (2-aminoethyltrimethoxysilane, (2-aminoethyl)triethoxysilane, (3-dimethylaminopropyl)trimethoxysilane, (3-dimethylaminopropyl)triethoxysilane, (2-dimethylaminoethyl)trimethoxysilane and (2-dimethylaminoethyl)triethoxysilane, and - 3.2 to 10.0 wt.% of at least one second organosilicon compound selected from the group consisting of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, dodecyltrimethoxysilane and dodecyltriethoxysilane. a) at least one organosilicon compound and b) at least one strengthening copolymer, which is made up of at least the following monomer units: - N-tert-octylacrylamide, - acrylic acid, and - tert-butylaminoethyl methacrylate and the INCI name "Octylacrylamide/Acrylates/Butylaminoethyl Methacrylate Copolymer," characterized in that the agent for treating a keratinous material contains, based on the total weight of the agent for treating a keratinous material: - 0.5 to 3.0 wt.% of at least one first organosilicon compound selected from the group consisting of (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, (2-aminoethyltrimethoxysilane, (2-aminoethyl)triethoxysilane, (3-dimethylaminopropyl)trimethoxysilane, (3-dimethylaminopropyl)triethoxysilane, (2-dimethylaminoethyl)trimethoxysilane and (2-dimethylaminoethyl)triethoxysilane, and - 3.2 to 10.0 wt.% of at least one second organosilicon compound selected from the group consisting of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, dodecyltrimethoxysilane and dodecyltriethoxysilane. - N-tert-octylacrylamide, - acrylic acid, and - tert-butylaminoethyl methacrylate and the INCI name "Octylacrylamide/Acrylates/Butylaminoethyl Methacrylate Copolymer," characterized in that the agent for treating a keratinous material contains, based on the total weight of the agent for treating a keratinous material: - 0.5 to 3.0 wt.% of at least one first organosilicon compound selected from the group consisting of (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, (2-aminoethyltrimethoxysilane, (2-aminoethyl)triethoxysilane, (3-dimethylaminopropyl)trimethoxysilane, (3-dimethylaminopropyl)triethoxysilane, (2-dimethylaminoethyl)trimethoxysilane and (2-dimethylaminoethyl)triethoxysilane, and - 3.2 to 10.0 wt.% of at least one second organosilicon compound selected from the group consisting of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, dodecyltrimethoxysilane and dodecyltriethoxysilane. - 0.5 to 3.0 wt.% of at least one first organosilicon compound selected from the group consisting of (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, (2-aminoethyltrimethoxysilane, (2-aminoethyl)triethoxysilane, (3-dimethylaminopropyl)trimethoxysilane, (3-dimethylaminopropyl)triethoxysilane, (2-dimethylaminoethyl)trimethoxysilane and (2-dimethylaminoethyl)triethoxysilane, and - 3.2 to 10.0 wt.% of at least one second organosilicon compound selected from the group consisting of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, dodecyltrimethoxysilane and dodecyltriethoxysilane.