I had always thought that blue and purple shampoo was only useful if you had bleached hair, but in fact, blue shampoo can do a lot for brown hair as well.
If you've ever gone brunette, you know that keeping it shiny and vibrant can be difficult sometimes. But blue pigment can do a lot to help preserve deep brown hair.
What does blue pigment do to brown hair?
Did you know that brown hair is a mix of all colors? However, the shade of brown depends on how much primary pigment you are working with. If your hair is deeper, it is because it has more red pigments, mid shades contain a bit more orange or reddish pigments, and light browns have almost all orange.
If you need to neutralize red, you should use a green pigment. If you are trying to neutralize orange pigments, you should add blue.
Blue shampoo works perfectly if your base tone is more on the dark brown side, and if you have highlights that have become a bit ashy or brassy.
Shampoing, sun exposure, hot tools, and swimming can cause orangey tones to come through and this is what makes your mane look dull.
If you want to avoid brassy hair, you should always go for a sulfate-free shampoo that won't damage your hair and you should also try a shampoo with blue pigments to counteract orange tones peeking through.
Bonus tip: If you are a brunette, and you happen to have grays, blue shampoo is great to keep your grays looking shiny!