Process for the treatment of human keratinous fibers

The invention relates to a process for densification of the hair, comprising a stage of application to the hair and/or the scalp of a composition consisting, in a physiologically acceptable medium, of an effective quantity of at least one precursor of densification chosen from among the compounds comprising at least one aromatic cycle having at least two hydroxyl groups borne by two consecutive carbon atoms of the aromatic cycle and an effective quantity of a catalytic system comprising one first constituent chosen from among the salts and oxides of Mn(II) and/or Zn(II) and mixtures thereof and a second constituent chosen from among the alkaline hydrogenocarbonates, the alkaline-earth hydrogenocarbonates and mixtures thereof. It also relates to a composition containing, in a physiologically acceptable medium, the said precursor of densification and catalytic system, combined with an active principle promoting the regrowth of hair, with delayed effect or for the dressing of the hair.