What is the purpose of a toner in hair coloring?

The purpose of a toner in hair coloring is to enhance the desired color. Toners are primarily used after the initial hair color application, especially in processes like bleaching, to adjust or modify the tone of the hair. This can involve neutralizing unwanted undertones, such as brassiness in blonde hair, or enriching certain hues, providing a more polished and balanced final result. Toners typically come in various shades, allowing for precise adjustments that complement the base color achieved through the initial coloring process.

While other options involve important aspects of hair care or coloring, they do not align with the specific function of a toner. For instance, changing the natural color is more a function of dye systems rather than toners, hydrating the hair pertains to conditioning treatments instead of toning, and creating a permanent bond is relevant to chemical processes like perming or relaxing, rather than the subtle adjustments toners provide.