Powder additive to reduce the damage of bleaching and colouring agents

A powder additive for a keratin fiber coloring or bleaching agent or developer, the powder additive comprising:

• 20 wt. % to about 80 wt. %, based on the total weight of the powder additive, of a dicarboxylic acid containing from about 2 to about 10 carbon atoms, selected from the group consisting of malic acid, D-tartaric acid, L-tartaric acid, meso-tartaric acid, racemic acid, alpha-ketoglutaric acid, beta-ketoglutaric acid, oxaloacetic acid, maleic acid, fumaric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sorbic acid, a salt of these dicarboxylic acids, and mixtures thereof;
• an amino acid or a salt of an amino acid;
• an alkalisilicate;
• a protein hydrolysate;
• and
• a polyvalent metal salt;
• wherein the powder additive has no greater than about 10% by weight water, based on the weight of the powder additive;
• and
• wherein the powder additive comprises particles and wherein at least about 80% of the particles have an average particle size of less than 200 μm.