12.01.16
US Patent No. 9,474,704 B2; Combe Incorporated has patented a method for gradually coloring hair. It entails the following steps: applying an air oxidation hair color composition to hair; removing the composition from the hair directly after application; and repeating a set of steps in multiple spaced intervals. The air oxidation hair color composition contains a grooming agent selected from the group consisting of a cleansing surfactant and a conditioning agent.