Patent ID: 6953486

Claim:
A composition comprising, at least one colouring agent precursor comprising at least one aromatic cycle having at least two hydroxyl groups bonded to two consecutive carbon atoms of the aromatic cycle, and optionally comprising at least one amino acid comprising at least one thiol group, and a catalytic system comprising a first component selected from the group consisting of salts of Mn(II), oxides of Mn(II), salts of Zn(II), oxides of Zn(II) and mixtures thereof, and a second component selected from the group consisting of alkaline hydrogenocarbonates, alkaline earth hydrogenocarbonates and mixtures thereof, in a physiologically acceptable medium, wherein the proportions of the first component and the second component in the catalytic system meet formulas (I)-(III) [ Mn ⁡ ( II ) ] [ HCO 3 ] ≤ 1 with [ Mn ⁡ ( II ) ] ≠ 0 [ Zn ⁡ ( II ) ] [ HCO 3 ] ≤ 1 with [ Zn ⁡ ( II ) ] ≠ 0 [ Mn ⁡ ( II ) + Z ⁢ ⁢ n ⁡ ( II ) ] [ HCO 3 ] ≤ 1 with [ Mn ⁡ ( II ) ] ⁢ ⁢ and ⁢ [ Zn ⁡ ( II ) ] ≠ 0 where [Mn(II)], [Zn(II)] and [HCO 3 ] represent respectively the Mn(II), Zn(II) and HCO 3 molar concentrations in the composition.