What is the primary use of a toner in hair coloring?

The primary use of a toner in hair coloring is to adjust the tone of the hair after lightening. When hair is lightened, it often takes on unwanted undertones, such as yellow or orange shades. Toners are specifically formulated to neutralize these undertones and create a more desirable color result. They work by depositing color onto the hair to achieve the desired hue, whether that be cooler shades like ash or warmer tones like gold.

While other products and techniques may be used to lighten hair, such as bleach, toners are essential for refining the final color after the lightening process. They do not typically serve the purpose of adding shine or conditioning the hair, as these features are accomplished through other products and treatments.