Tones Unwanted Color
A toner is a more transparent type of hair color that is used to eliminate unwanted tones in hair that has been bleached or colored improperly. For instance, bleached blondes may have unwanted brassy yellow colors or some reds have hints of orange tones. In order to tone out the brassy colors, toners are applied to remove those unwanted colors.
Alters Hair Color
Choosing the wrong shade toner alters hair color. For instance, if a green or blue based toner is applied to yellow blonde hair, the result ranges from a gray to green tint. Therefore, it is important to choose the toner correctly to tone out brassy tones while maintaining the overall hair color.
Bottom Line
According to hair-colour.info, toners should be left on hair for approximately 15 to 20 minutes. Choose the appropriate color and perform a strand test before attempting to apply the toner. Toners are not created equally and have different instructions for use. Therefore, follow the directions on the box or bottle of toner for the best results.