Hair-conditioning agent and method for oxidative hair dyeing with improved brightening performance

A method for the oxidative dyeing of keratin fibers comprising the following method steps:

• I. Providing a composition (A) comprising, based on its weight,
• a) at least one compound selected from the group of oxidation dye precursors, direct dyes, and mixtures thereof,
• b) at least one dicarboxylic acid having 2 to 10 carbon atoms and/or at least one salt of these acid(s) in a total quantity of from about 0.1 to about 5% by weight, calculated respectively on the undissociated dicarboxylic acid and based on the weight of the composition (A),
• c) at least one keratin hydrolyzate having an average molecular weight Mw in the range from about 2000 to about 7000 daltons,
• d) from about 20 to about 95% by weight of water, and
• e) zero to less than about 0.1% by weight of peroxide compound(s),
• II. Providing a composition (B) comprising at least one peroxide compound, in an amount of from about 1 to about 23% by weight, based respectively on the weight of the composition (B), wherein the composition (B) has a pH value in the range of from about 2.5 to about 6.5,
• III. Mixing the compositions (A) and (B) with each other, directly afterward
• IV. Applying the mixture of (A) and (B) to the keratin fibers, and
• V. Rinsing after an exposure time of from about 0.1 to about 60 minutes.