A kit for a polymerisable composition, said kit comprising: I. a portion A constituted by a composition comprising at least one monomer that is reactive towards a cationic species or a Lewis or Brönsted acid species, and at least one co-initiator (b); II. a portion B optionally comprising a solvent and/or at least one monomer that is reactive towards a cationic species or a Lewis or Brönsted acid species, and at least one cationic salt (e) selected from the salts with formula S1, S3, and S4 below; in which X represents a carbon atom or a positively charged heteroatom other than nitrogen; Y represents one or more stabilizing anionic species for the cationic species of the salt S1 or S3, or S4, in particular comprising at least one anionic species selected, alone or in combination, from Br -, Cl -, BF 4 -, PF 6 -, AsF 6 -, AnF 6 -, SbF 6 -, SnF 6 -, ClO 4 -, sulfonates; R 1 to R 6, independently of one another, are selected from the following atom or atoms or group or groups, alone or in combination, optionally arranged so as to carry one or more positive charges: a hydrogen atom; a nitro group -NO 2; a cyano group -CN; a halogen atom; a C 1 -C 20 alkyl group, optionally substituted with one or more group(s) or one or more atom(s) selected independently from list I comprising the following groups or atoms: hydroxyl; carbonyl, alkenyl, aryl, heteroaryl, ether, ester, aldehyde, ketone, carboxylic acid, a halogen atom, primary amine, secondary amine, tertiary amine, primary amide, secondary amine, tertiary amine, urea, thioester, thiocarbonate, sulfoxide, sulfone, phosphine, phosphorane, phosphine oxide, cycloalkyl, heterocycloalkyl, or combinations thereof; a C 1 -C 20 alkoxy group, optionally substituted with a C 1 -C 20 alkyl group and/or one or more group(s) or one or more atom(s) selected equally well from list I; an aryl group; a heteroaryl group; a cycloalkyle group; a heterocycloalkyl group; the or said (hetero)aryl groups and/or the or said (hetero)cycloalkyl groups optionally being substituted with one or more group(s) independently selected from list I; an acyl group; an aroyl group; an alkoxycarbonyl group; a carbamyl group; and optionally a photosensitizer (c) that may equally well be in the portion A and/or in the portion B. I. a portion A constituted by a composition comprising at least one monomer that is reactive towards a cationic species or a Lewis or Brönsted acid species, and at least one co-initiator (b); II. a portion B optionally comprising a solvent and/or at least one monomer that is reactive towards a cationic species or a Lewis or Brönsted acid species, and at least one cationic salt (e) selected from the salts with formula S1, S3, and S4 below; in which X represents a carbon atom or a positively charged heteroatom other than nitrogen; Y represents one or more stabilizing anionic species for the cationic species of the salt S1 or S3, or S4, in particular comprising at least one anionic species selected, alone or in combination, from Br -, Cl -, BF 4 -, PF 6 -, AsF 6 -, AnF 6 -, SbF 6 -, SnF 6 -, ClO 4 -, sulfonates; R 1 to R 6, independently of one another, are selected from the following atom or atoms or group or groups, alone or in combination, optionally arranged so as to carry one or more positive charges: a hydrogen atom; a nitro group -NO 2; a cyano group -CN; a halogen atom; a C 1 -C 20 alkyl group, optionally substituted with one or more group(s) or one or more atom(s) selected independently from list I comprising the following groups or atoms: hydroxyl; carbonyl, alkenyl, aryl, heteroaryl, ether, ester, aldehyde, ketone, carboxylic acid, a halogen atom, primary amine, secondary amine, tertiary amine, primary amide, secondary amine, tertiary amine, urea, thioester, thiocarbonate, sulfoxide, sulfone, phosphine, phosphorane, phosphine oxide, cycloalkyl, heterocycloalkyl, or combinations thereof; a C 1 -C 20 alkoxy group, optionally substituted with a C 1 -C 20 alkyl group and/or one or more group(s) or one or more atom(s) selected equally well from list I; an aryl group; a heteroaryl group; a cycloalkyle group; a heterocycloalkyl group; the or said (hetero)aryl groups and/or the or said (hetero)cycloalkyl groups optionally being substituted with one or more group(s) independently selected from list I; an acyl group; an aroyl group; an alkoxycarbonyl group; a carbamyl group; and optionally a photosensitizer (c) that may equally well be in the portion A and/or in the portion B.