The present invention relates to a cosmetic process for treating a keratin material, characterized in that it comprises at least one step of applying to the said keratin material a coating formed from a liquid composition comprising, in a cosmetically acceptable medium, at least one copolymer containing polyamide blocks and polyether blocks resulting from the co-polycondensation of polyamide blocks containing reactive ends with polyether blocks containing reactive ends the said copolymer being in solution or in dispersion, and at least one organic solvent. The present invention also relates to a cosmetic assembly comprising a) at least one liquid composition comprising, in a cosmetically acceptable medium, at least one copolymer containing polyamide blocks and polyether blocks in solution or in dispersion, and at least one organic solvent b) a device for applying the said composition to the keratin materials.
