What is the primary function of a hair toner?

The primary function of a hair toner is to neutralize unwanted undertones in the hair. When hair is lightened, especially during the bleaching process, it can sometimes reveal undesired colors, such as yellow or orange hues. Toners are specifically designed to adjust the shade of the hair by counteracting these unwanted tones. For example, a purple toner might be used to eliminate yellow tones, while a blue toner could help neutralize orange hues. This process helps achieve a more balanced and aesthetically pleasing color result after lightening, making toners an essential tool in achieving the desired hair color.

Other options do not align with the primary function of toners. While lightening hair color is a separate process done with bleach, adding volume typically pertains to styling products rather than toners, and UV protection is usually provided by specialized hair care products rather than toners.