Hair toner corrects the color tones in hair, including unwanted brassy, coppery or reddish colors. Advantages of using a toner include softening the transition between outgrowth and colored hair, sealing hair color so that it lasts longer and adding shine to color-treated hair.
Toner can act as a filler for damaged hair, evening the porosity of hair from root to tip and giving color a more uniform look. Toner is typically applied by itself or after hair coloring to even out hair color, making differences between colors more subtle. Application of toner may slightly darken hair color, particularly at the roots where the hair has been processed fewer times.