What is a toner used for in hair coloring?

A toner is primarily used in hair coloring to correct brassiness and achieve a more polished and desired shade. It typically contains color pigments that neutralize unwanted warm tones, such as yellows and oranges, which can appear after the lightening process. Toners can provide a more balanced and refined color, making them particularly valuable for those with blonde, gray, or highlighted hair.

Lightening hair, perming, or adding volume are actions that involve different processes or products. Lighteners, for example, are specifically designed to remove or lift the natural pigment from the hair. Perms involve chemical processes to create curls or waves, and volumizing products are used to add body to the hair. Toners serve a distinct purpose in enhancing and refining color, which is why the correct answer focuses on correcting brassy tones.