An oxidation colorant for coloring keratin-containing fibers with atmospheric oxygen as the sole oxidizing agent

Agent for coloring keratin fibers which comprise at least one dye precursor for a nature-analogous dye selected from the group of indole or indoline derivatives, at least one pH buffer system and at least one further alkalizing include, and are free of additional oxidizing agents, an increased dyeability on. These agents can be stored for a long time without having to accept a significant loss in the coloring power.