Shaping keratin fibres using an active agent comprising a functional group selected from the group consisting of: -c(=o)-, -c(=o)-h, and -c(=o)-o-

A method for shaping keratin fibres comprising:

• (a) providing a solid composition, wherein the solid composition comprises:
• an active agent, wherein the active agent comprises a functional group selected from the group consisting of:
• —C(═O)—, —C(═O)—H, and —C(═O)—O—;
• and wherein the active agent is not an acid;
• wherein the active agent has a molecular weight of about 500 g/mol or less;
• a photocatalyst being a hydroxy-substituted aromatic compound;
• and then mixing the solid composition with a cosmetically acceptable carrier to form a crosslinking composition;
• (b) applying the composition to keratin fibres, mechanically shaping the keratin fibres with an appliance or implement, and exposing the composition to electromagnetic radiation having a wavelength of from about 300 nm to about 750 nm.

A crosslinking composition for shaping keratin fibres comprising:

• an active agent, wherein the active agent comprises a functional group selected from the group consisting of:
• —C(═O)—, —C(═O)—H, and —C(═O)—O—;
• and wherein the active agent is not an acid;
• and wherein the active agent has a molecular weight of about 500 g/mol or less;
• a photocatalyst being an aromatic hydroxy compound, wherein the aromatic hydroxy compound is multicyclic.