| abstract |
A concentrated aqueous solution of a p-phenylenediamine derivative, which a) has a pH higher than 12.5, b) contains 0.4 to 1.1 mol p-phenylenediamine derivative/litre, c) contains 0.05 to 2 mol of an antioxidant/litre, d) contains at most 35% by weight of organic solvents with respect to the total solution, e) contains at most 50 mmol sulphate ions/litre and f) is single-phase, is suitable for the production of different colour developer formulations. |