Anyone who has ever colored their hair has likely heard about toner before. But what is hair toner, exactly? Not to be confused with the stuff you swipe on your face, hair toner is an essential part ...

However, not all blonde toners are created equal. Some are rinse-out, some are leave-in, and some are good, old hair masks.

If you have color-treated hair (hi, yes, me), you know that you only have a handful of weeks before your color—blonde or brunette—starts to pick up some unwanted brassy or warm tones. It’s normal.