Brassy hair toner is a substance that is applied to hair to remove a brassy color. Hair can become brassy when the ammonia and peroxide in hair dye intensifies a person's natural hair color.
A shampoo for violet-toned hair can serve as a brassy hair toner. The shampoo cancels out the brassy color by depositing surface color onto hair. According to ThePerfumeExpert.com, Black Malva shampoo and conditioner from Aveda is also ideal for removing brassy color from hair. The products take the red out of brown hair. ThePerfumeExpert.com also recommends that blondes whose hair has become brassy should try Caviar Anti-Aging Brightening Blondes shampoo and conditioner to restore a desirable color.