Can I use the mixed hair dye the next day? Please, don’t! Here’s why

handle dye with gloves

  • The mixed hair dye should always be used right after it’s prepared.
  • If you use the mixed hair dye the next day, you’ll damage your hair and scalp severely. You may even get intoxicated.
  • Also, the color won’t settle evenly in your hair.


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When you’ve been working in a salon for a long time, you get used to many things.

For example, you get used to clients insisting on having the haircut of an Instagram model even if it doesn’t flatter them at all and, even worse, highlight the features they don’t like.


You also get used to clients who want to be taken care of in ten minutes, even if the coloring job takes two hours.

Of course, you also get used to dealing with hair damaged by home bleaching.


But what I can never get used to is the crazy ideas.

  I’ve never heard such a crazy idea as using the mixed hair dye the next day. 


But worst of all, one of my clients didn’t just come up with that idea.

She directly used the mixed hair dye the next day.

She went from idea to action.


The   consequences were catastrophic.  

I’m not exaggerating.


This is the story.

She prepared the dye, and when she was about to apply it, one of her friends called her with a “sentimental emergency.”


You know what it means to friends.


We put aside whatever we are doing to immediately respond to the call for help.

That speaks very well of my client. Friends are a treasure to be treasured.


So, she didn’t apply the dye that day.

The next day, when she woke up, she saw the hair dye mixture ready.


Without thinking twice, and before receiving another call for help from her friend, she applied it to her hair.

What follows is a chronicle of a hair disaster.

  • The first ten minutes after applying the mixed hair dye,   she began to feel a terrible itch on her scalp.   She decided to wait. After all, she thought a little itching was normal.
  • Within twenty minutes,   the itching had turned into a terrible burning.   It was so terrible that even at times she couldn’t help scratching her scalp.
  • After thirty minutes,   the burning turned to pain.   Then, she sensed something was wrong and decided to rinse the dye off.
  •   When she tried to untangle her hair, she discovered in horror that strands were trapped in the brush.   Right then and there she ran off to my salon for help.


The mixed hair dye from the previous day had ruined her hair. Both the peroxide and the developer were degraded.

Do you know what the worst part was?


I couldn’t help her as much as I would’ve liked.

I could only trim ten centimeters of her hair to try to remove the damaged part.

I recommended that she make an appointment with a dermatologist.   Her scalp had some injuries that needed to be treated.  

I don’t want to scare you, but I must be clear.

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The mixed hair dye can’t be saved or stored to be used the next day

cover ombre with dye at home

This is because of a chemical reaction that neither you nor the best hairdresser in the world can change.

  The day after preparing the dye, chemicals such as peroxide and ammonia degrade.  

What does this mean?


When you mix the developer and ammonia to prepare the dye, they generate a chemical reaction that changes the color of your hair.

Of course, this reaction has a beginning and an end. It doesn’t last forever. So, at some point, it’ll stop.

When will it stop?


After about twenty minutes.

The dye mixture’s process is divided into stages:

  • Initiation: when you mix the elements.
  • Reaction: when the dye changes color. The mixture is usually white when you apply it. But after a few minutes, it turns to a different color in your hair. That’s the reaction.
  • Degradation: when the mixture finished the reaction.


  The dye mixture is effective up to 45 minutes after preparing it.   It’s most effective during the first 20 minutes.


Then, the degradation, or “the expiration”, as we stylists call it, begins.

All the products we consume and use have an expiration date.

What does this expiration date tell us?


If the product is consumed or used before that date, it’ll be in optimal conditions.

  If you use it after that date, the product will be degraded or expired.  


The prepared dye has a shelf life of 40 to 45 minutes, which is the exposure time.

This brings us to the next question.


What could happen if you apply the mixed hair dye to your hair the next day?

porous hair without elasticity

Something similar to my client’s story will happen.

  You’ll suffer quite serious consequences, both in your hair health and in the coloring results.  

Let’s start with the most important thing.


If you use the mixed hair dye the next day, you’ll damage your hair and injure your scalp

Once the reaction ends, the mixture will no longer be creamy because its consistency will have changed.

Therefore, the mixture will be liquid. That change isn’t a good thing.


The chemical residue left by the developer and ammonia is a colored liquid.

If you apply the liquid dye mixture, your hair will begin to absorb it and distribute it from root to tip, as if it were water.

But it’s not water. It’s degraded chemicals. Therefore,   your hair will start to get damaged.  

What will happen?


  • Frizz and tangles will appear.
  • Hair breakage from the root will occur.
  • Dryness in lengths and ends.
  • Scalp irritation.


In short,   you’ll have irreversibly damaged your hair.  

Hair breakage from the root isn’t solved with a haircut.


If you use the mixed hair dye the next day, the color will be uneven

different color between roots and ends

Of course, at this point, it’ll be the least of your worries.

An uneven color can be fixed, but   ruined hair sometimes has no solution. 

However, I’ll explain what will happen to your hair color if you use the mixed hair dye the next day.


Some areas of your hair, such as the ends, roots, mid-lengths, and frontal areas, are especially sensitive to any type of product you apply.


They’re exposed to friction, delicate, and prone to lose moisture.

It’s precisely   in these more fragile areas that the degraded hair color is more quickly absorbed. 


Therefore, when you rinse out the mixed dye, you’ll notice that those areas absorbed the color, while the rest of your hair remains the same color as before applying the dye.

You’ll have color stains all over your hair.



Once you mix the dye components, you have 45 minutes to use it. After 45 minutes, the dye is degraded or expired and should be discarded.

It’s better to lose some mixed hair dye than to deal with damaged hair and injury to the scalp.

The mixed hair dye can’t be stored or used the following day.

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