If you’ve ever had on-the-scalp color, even if your stylist chooses the same color you had in your youth, you may notice that it looks warmer than your natural color ever was. This can be annoying if you don’t understand what’s happening and what you can do to help. 

Stylists don't control the behavior of color molecules, they manipulate them within the predetermined confines of chemistry.

Every color is made of the three primary colors: blue, red, and yellow. That is, every color except the three primaries because they’re their own color. The color molecules interact with one another through chemical and/or physical manipulation to form new colors. 

In hair, the color molecules are predictable and, unless the hair has been damaged, always behave the way they’re supposed to. This is how an educated colorist can manipulate the color molecules in your hair with enough precision to create the desired level and tone within a small margin of error. 

Hair loses the color molecules in a specific order: blue comes out first and reveals red. Red comes out next and reveals yellow. After all the yellow is out, the hair has disintegrated. Hair accepts color molecules in the exact reverse: yellow is first, and without it, it cannot accept red. Red is next, and without it, it cannot accept blue. Blue is the last to be accepted, and it’s the one that helps neutralize the warmth of red and yellow. It also turns hair brown. As a bit of extra knowledge, hair that has lost all yellow pigment (the disintegrated hair) will not accept color properly, so don’t ever ask your stylist to remove all of the yellow unless you want a pixie cut.

Gray hair comes with its own set of challenges and limitations. 

Gray hair, by definition, has no pigment and resists color molecules. A colorist must establish the proper balance of yellow, red, and blue color molecules to mimic natural hair color as close to the desired level and tone as possible. The lighter the desired result (dark blonde to light blonde), the more warmth you’ll see because remember, the blue in any meaningful volume turns the hair brown. If you want coverage at all, your colorist must contend with the reality of red and yellow.

"Cool" colors don't cover gray, so your stylist has to get creative to achieve the desired tone. And they need your trust and cooperation to pull it off.

If you’re getting your grays covered and you want your hair blonde with as little red or yellow showing as scientifically possible, then you must go darker on your base color and add highlights to brighten it up. Your colorist will then use a toner on your highlighted hair to create a “cool” reflect. 

There are limitations with any color. The more your stylist knows, the more they can control the outcome. The more their clients know, the more reasonable their expectations and appreciation for the balance of chemistry and art that a stylist walks for them. 

There are practical things you can do at home to protect the work your stylist did to neutralize the reds and yellows.

1. Keep your shower water as cool as possible, and enjoy your shower.

2. Use the products your stylist recommends for you. It really does matter.

3. Limit heat styling as much as you can.

4. Protect your hair from the sun.