How long can you keep mixed hair dye? One hour at the most

box hair dye to cancel orange

  • The mixed dye is good for one hour. This means that you have one hour to use it since you finish preparing it.
  • If it takes more than an hour, you won’t be able to change the color of your hair, and you’ll damage it.
  • You need to the dye immediately one hour after having prepared it.


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Believe it or not, I know about women who  mix the dye, but they cannot apply it at the moment. 


Yes, women’s lives can be very complicated.

And this happened to one of my clients.

Since she didn’t have time to come to the salon, she decided to color her hair. She took the kids to school, went home, enjoyed a tasty breakfast, and decided to prepare the dye.


As she was about to apply the dye, her cell phone rang. She wasn’t going to answer the call, but her maternal instinct called out.

It was a call from the school. Her child was feeling sick and had to be picked up.

So, she quickly changed and ran out to pick up her little boy,  leaving the dye mixed. 


When she returned home, the first thing she did was to attend to her little boy. And after making sure he was ok, she decided to continue coloring her hair.


 Three hours had passed. 

She whisked the product again because there was a kind of foam on top of it.

She applied the dye and let it act for about forty minutes.


After rinsing the dye, she noticed that her hair hadn’t changed colors.

And the worst part was that after an hour, she began to feel a terrible itching on her scalp.

What had happened?


 The mixed dye was no good at the time of application because it had been more than an hour since she had mixed it. 


Luckily, she asked a dermatologist, and she immediately recommended medication to relieve the scalp irritation.

Unfortunately, her hair was seriously damaged. And in that case, I was the one who recommended intensive repair treatment.


My client learned that the mixed dye can be kept on for an hour at most.

And here’s why.

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One hour after mixing the dye, it loses the strength of the reaction and can’t modify the hair color

golden blonde hair dye

Therefore,  once the dye is mixed, you can use it in the next 45 to 60 minutes. 



Let’s look at what a dye mix is.

The dye color you chose contains ammonia to fix the pigments inside the hair. And the developer, or hydrogen peroxide, opens the hair cuticles so that the color can penetrate inside the hair and oxidize the dye.

When you start mixing the developer and the dye, the mixture is almost white or yellowish. But after a few minutes, the color changes.


And when the color changes, it’s because oxidation has occurred.

That process continues in your hair when you start applying the mixed dye. After twenty minutes, you’ll notice that the mixed dye starts to darken in your hair until it reaches the color you chose.


This chemical reaction has a maximum time of one hour, starting from mixing the dye with the developer.

 After this time, the mixture no longer generates a chemical reaction that can change the color of your hair,  and the chemicals involved only damage the hair.


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Now, you know why mixed dye lasts for an hour. It’s just a chemical reaction that has to be respected. Otherwise, nothing good will happen to your hair.


If you apply the mixed dye after one hour, you’ll damage your hair and the color won’t change

fix uneven hair color

Hair is part of your body, and it’s as important as your skin.

Do you agree with this?



Then, you’ll agree with some things too. For example:

  • You’d never apply an expired moisturizer to your face.
  • You wouldn’t let a professional makeup artist apply expired makeup to your face.
  • Before using a moisturizer for the first time, you’d apply a small amount to your wrist to make sure it wouldn’t cause an allergic reaction.


And you’d do all this because any expired cream or makeup product can hurt your skin or cause an allergic reaction.

You should take the same care with your hair.

Shall I tell you what would happen with the mixed hair dye you’ve prepared well in advance?


 After an hour, you’ll notice that the mixed dye looks a bit strange. 
  • There could be foam on the mixed dye, which is a residue from the reaction of the hydrogen peroxide with the ammonia
  • Then, you might see a liquid in the middle. It’s the residue of the vapors produced by the chemical reaction as the temperature rises.
  • At the bottom, you’d see an aqueous cream, which is the residue of the dye mixture because the peroxide and ammonia separated leaving a lumpy mixture.


If you use the dye that has been prepared for more than an hour, do you know what would happen to your hair?

  •  Your hair would absorb the residue from the chemicals and dry out from the roots.  That drying would lead to breakage and frizz. In other words, it’ll ruin your hair.
  •  Your hair would be stained  because the dye would not set evenly.
  •  Your scalp would be irritated by the action of the chemical residue, which can cause swelling, redness, burning, stinging, and itching. Hopefully, you have a dermatologist friend nearby.


If you want to save some money by using a dye mixed more than an hour ago, it’s not the best choice.

Throw the dye away, and use a new one. Otherwise, you’ll just ruin your hair, and spend even more money repairing it.



The mixed dye should be applied within one hour after being prepared. Then, you discard it because it won’t change the color of your hair and you’ll damage it severely.

If you cannot apply the mixed dye once it has been prepared, discard it.

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