A method, a kit and a first composition for treating hair are provided. The method for treating hair comprises applying to the hair a first composition comprising in a cosmetically acceptable carrier, one or more linkers, or cosmetically acceptable salts thereof, or mixtures thereof； and applying to the hair a second composition comprising in a cosmetically acceptable carrier, one or more electrophile ingredients of Formula I, or cosmetically acceptable salts thereof, or mixtures thereof:and wherein the first composition does not comprise any electrophile ingredients of Formula I of the second composition.
