Toner is a semi-permanent hair color that is used to change the tone of your hair. It can be used to correct brassiness, add warmth, or create a completely new look. Toner is typically applied to bleached or highlighted hair, but it can also be used on natural hair.
The length of time you leave toner on your hair will depend on the type of toner you are using and the desired results. In general, you should leave toner on for no longer than 30 minutes. If you leave toner on for too long, it can damage your hair and cause it to become dry and brittle.