You were pretty happy with your recent dye job—until you noticed those brassy or yellowish undertones to your hair. This is why so many people who do regular coloring swear by the use of a good hair toner, which will neutralize those undertones, an unfortunate regularity when dying your hair, especially if you’re making a drastic color change.
The concept behind hair toner is in the way it counteracts the underlying pigments in your hair—they infuse your hair with just enough of the opposite color that it nicely tones your dye job. So, for example, if you have yellowish undertones, a purple toner could give you the color you need; if your problem is brassiness, a blue toner could do the trick.
Applying hair toner is an important part of the hair dying process, so most people who have their hair professionally colored will already have toning done. However, if you dyed your hair at home, you would need to use an at-home toner product, especially if you bleached your hair, highlighted your hair, or have naturally gray or silver hair. You could also use a toner to fix overly warm or cool tones.
If your newly dyed hair is…
…blonde, use purple to neutralize yellowness and cool down any excess warmth so that it looks more natural.
…brown, use a blue or green toner to play down any red undertones and give your hair a cooler, ashier shade of brown.
…red, a green toner will subdue any brassiness and give you a vibrant shade of red without any excessive warmth.
