The invention relates to a method for protecting keratinous materials, particularly the skin, against UV radiations comprising applying successively, to the keratinous materials: 1/ a base composition comprising an UV filter, 2/ a finishing composition comprising an UV filter, wherein at least one of the base composition or the finishing composition comprises at least one compound chosen from: - a silicon polymer A having silicon-bonded alkenyl groups called "Si-Alkenyl" groups, - a silicon polymer B having silicon-bonded hydrogens groups called "SiH" groups, - a catalyst C, and mixtures thereof, with the proviso that: - at least one polymer A, one polymer B and one catalyst C are present in either the base or the finishing composition, and that - the polymer A, the polymer B and the catalyst C are not present simultaneously in the same composition, said polymer A and polymer B being capable of reacting together by a hydrosilylation reaction in the presence of said catalyst C when they are contacted with one another, in order to form, on the keratinous material, a continuous protecting film against UV radiations.Linvention concerne un procédé de protection de matières kératiniques, en particulier de la peau, contre les rayonnements UV comprenant lapplication successive sur les matières kératiniques : 1/ dune composition de base comprenant un filtre UV, 2/ dune composition de finition comprenant un filtre UV, la composition de base et/ou la composition de finition comprenant au moins un composé choisi parmi : - un polymère de silicium A ayant des groupes alcényle liés au silicium appelés groupes " Si-alcényle ", - un polymère de silicium B ayant des groupes hydrogène liés au silicium appelés groupes " SiH ", - un catalyseur C, et leurs mélanges, à condition que : au moins un polymère A, un polymère B et un catalyseur C soient présents soit dans la composition de base, soit dans la composition de finition, et que - le polymère A, le polymère B et le catalyseur C ne so
