Composition comprising: (a) one or more alkoxysilanes bearing solubilizing function(s) of formula below, and/or hydrolysis products thereof and/or oligomers thereof: R 1 Si(OR 2) z (R 3) x y in which: R 1 is a linear or branched, saturated or unsaturated, cyclic or acyclic C 1 -C 6 hydrocarbon-based chain substituted with one or more groups chosen from the following groups: - amine NH 2 or NHR, R being: ∘ a C 1 -C 20 and preferably C 1 -C 6 alkyl group optionally substituted with a group comprising a silicon atom, ∘ a C 3 -C 40 cycloalkyl group or ∘ a C 6 -C 30 aromatic group, - hydroxyl, - thiol, - aryl or aryloxy substituted with an amino group or with a C 1 -C 4 aminoalkyl group, R 1 possibly being interrupted with a heteroatom such as O, S or NH, or a carbonyl group, R 2 and R 3, which may be identical or different, represent a linear or branched alkyl group comprising from 1 to 6 carbon atoms, y denotes an integer ranging from 0 to 3, z denotes an integer ranging from 0 to 3, and x denotes an integer ranging from 0 to 2, with z + x + y = 3, (b) one or more alkylalkoxysilanes of formula below, and/or hydrolysis products thereof and/or oligomers thereof: (R 4) m Si(OR 5) n in which: R 4 and R 5 each represent, independently of each other, a C 1-6, better still C 1-4, alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl, preferably methyl, ethyl or n-propyl, n ranges from 1 to 3, m ranges from 1 to 3, on condition that m+n=4, and (c) one or more fatty substances wherein the compounds (a) and (b) are present in an (a)/(b) weight ratio ranging from 0.5 to 10. (a) one or more alkoxysilanes bearing solubilizing function(s) of formula below, and/or hydrolysis products thereof and/or oligomers thereof: R 1 Si(OR 2) z (R 3) x y in which: R 1 is a linear or branched, saturated or unsaturated, cyclic or acyclic C 1 -C 6 hydrocarbon-based chain substituted with one or more groups chosen from the following groups: - amine NH 2 or NHR, R being: ∘ a C 1 -C 20 and preferably C 1 -C 6 alkyl group optionally substituted with a group comprising a silicon atom, ∘ a C 3 -C 40 cycloalkyl group or ∘ a C 6 -C 30 aromatic group, - hydroxyl, - thiol, - aryl or aryloxy substituted with an amino group or with a C 1 -C 4 aminoalkyl group, R 1 possibly being interrupted with a heteroatom such as O, S or NH, or a carbonyl group, R 2 and R 3, which may be identical or different, represent a linear or branched alkyl group comprising from 1 to 6 carbon atoms, y denotes an integer ranging from 0 to 3, z denotes an integer ranging from 0 to 3, and x denotes an integer ranging from 0 to 2, with z + x + y = 3, R 1 is a linear or branched, saturated or unsaturated, cyclic or acyclic C 1 -C 6 hydrocarbon-based chain substituted with one or more groups chosen from the following groups: - amine NH 2 or NHR, R being: ∘ a C 1 -C 20 and preferably C 1 -C 6 alkyl group optionally substituted with a group comprising a silicon atom, ∘ a C 3 -C 40 cycloalkyl group or ∘ a C 6 -C 30 aromatic group, - hydroxyl, - thiol, - aryl or aryloxy substituted with an amino group or with a C 1 -C 4 aminoalkyl group, - amine NH 2 or NHR, R being: ∘ a C 1 -C 20 and preferably C 1 -C 6 alkyl group optionally substituted with a group comprising a silicon atom, ∘ a C 3 -C 40 cycloalkyl group or ∘ a C 6 -C 30 aromatic group, ∘ a C 1 -C 20 and preferably C 1 -C 6 alkyl group optionally substituted with a group comprising a silicon atom, ∘ a C 3 -C 40 cycloalkyl group or ∘ a C 6 -C 30 aromatic group, - hydroxyl, - thiol, - aryl or aryloxy substituted with an amino group or with a C 1 -C 4 aminoalkyl group, R 1 possibly being interrupted with a heteroatom such as O, S or NH, or a carbonyl group, R 2 and R 3, which may be identical or different, represent a linear or branched alkyl group comprising from 1 to 6 carbon atoms, y denotes an integer ranging from 0 to 3, z denotes an integer ranging from 0 to 3, and x denotes an integer ranging from 0 to 2, with z + x + y = 3, (b) one or more alkylalkoxysilanes of formula below, and/or hydrolysis products thereof and/or oligomers thereof: (R 4) m Si(OR 5) n in which: R 4 and R 5 each represent, independently of each other, a C 1-6, better still C 1-4, alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl, preferably methyl, ethyl or n-propyl, n ranges from 1 to 3, m ranges from 1 to 3, on condition that m+n=4, and R 4 and R 5 each represent, independently of each other, a C 1-6, better still C 1-4, alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl, preferably methyl, ethyl or n-propyl, n ranges from 1 to 3, m ranges from 1 to 3, on condition that m+n=4, (c) one or more fatty substances