Abstract: The present invention relates to a method for semipermanent straightening and dyeing of the hair in two steps. The method uses a first composition (straightening composition) comprising at least one carboxylic acid of the Formula (I), and a second composition (dye composition) comprising at least one hair dye, optionally at least one alkalizing agent and optionally at least one oxidizing agent. The hair is treated with the said compositions successively, so that the dyeing treatment is performed directly after the straightening treatment.

Abstract: The present invention relates to a method for semipermanent straightening and bleaching of the hair in two steps, which are carried out one after another in one salon visit. For this purpose, the method of the present invention uses a first composition (straightening composition) comprising at least one carboxylic acid of the Formula (I) and a second composition, (bleaching composition) comprising least one oxidizing agent and at least one alkalizing agent. The hair is treated with the said compositions successively, so that the bleaching treatment is performed directly after the straightening treatment.

Abstract: The present invention provides methods for simultaneously colouring and straightening the hair, for straightening the hair directly before or after a colouring treatment, and for straightening the hair directly before or after a bleaching treatment. Besides, the present invention also provides a method for straightening the hair by drying the hair with hot air under conditions of mechanical tension. The straightening methods of the present invention utilize compositions containing formaldehyde.