How Long to Leave Bleach in Hair 30 vol? Bleach your hair safely

  • You should always leave the 30-volume bleach in your hair for a maximum of 20 minutes.
  • It doesn’t matter if you want to go from black to blonde hair or from light brown to light blonde. The exposure time of the 30-volume bleach cannot exceed 20 minutes.
  • If your hair doesn’t lighten to your expected shade those twenty minutes, you’ll have to bleach it again in 3 weeks.
  • If you leave the developer in for longer, you’ll burn your hair fiber, and it’ll eventually break.


three shades

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Unfortunately, thanks to the “misinformation” on the internet these days, I’m getting more and more work at the hairdresser’s every day.

Why do I say “unfortunately”?


30% of the cases are people who decided to bleach their hair at home. However, the only thing they achieved was to burn their hair.

When that happens, believe me, the only solution is scissors. I have to cut the damaged bleached hair up to 15 centimeters sometimes.


You need to understand!

Bleaching is a very aggressive chemical process for hair.

 If you want to bleach your hair correctly and safely, you should have it done by a trained professional. 


For example, one of the things around the internet universe is that “the exact time you should let the 30-volume bleach on depends on your goal and your natural hair color“. That’s a lie.

 Regardless of your goal, your base color, and the color you want to achieve, you should always leave the bleach on for a MAXIMUM OF 20 MINUTES. 


developer and bleaching powder

The last straw that made me shiver was to find this statement: “If you want to go from black to blonde hair, you should leave the bleach on for a maximum of 40 minutes“.


No one goes from black hair to blonde in thirty minutes. No one who wants to keep some of their hair on their head.


So, you have two ways:

  •  Leave the 30-volume bleach in the hair for a maximum of 20 minutes checking minute by minute the reaction.  believe a hairdresser who works on coloring techniques for years.
  • Leave the bleach on as long as recommended by people who can’t tell the difference between human hair and horsehair. My apologies to horses.


What do you decide; do you need more information to decide?

Then, let’s start at the beginning.

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How does the 30-volume bleach works on your hair?

to blonde

You shouldn’t leave the mixture on your hair for more than twenty minutes if you want to keep it.

It isn’t my invention or that of a strict hairdresser. It’s simply a matter of chemistry.


You probably intend to bleach your hair. And bleaching uses two chemical elements:

  • Bleach powder or ammonia
  • 30-volume developer or hydrogen peroxide

How do these chemicals work?


The 30-volume developer opens your cuticles, which are tiny flakes lodged in your hair fiber, for the bleaching powder to penetrate to the core and push out all the pigmentation. That chemical reaction generates heat.

Therefore, the hair becomes extremely dry. The heat causes the evaporation of the hair’s natural moisture.

That process lasts the famous 20 minutes.


 From the moment you finish applying the mixture, the clock starts ticking. 

After 20 minutes, the bleach will no longer be strong enough to cause the chemical reaction that lightens the hair. Still, it’ll be strong enough to damage and burn it.


 When hair loses its natural moisture, it automatically starts to absorb any product you apply to it. It doesn’t distinguish between good and bad. 

Do you understand?


From the 21st minute onwards, your hair starts a long road of no return. It’s the road of breakage, split ends, dryness, and frizz.

Your hair won’t get lighter even if you leave the bleach on for more than 20 minutes. Nor will you be able to lighten your black hair to platinum blonde. You’ll only be able to lighten your hair gradually up to 3 or 4 shades at each bleaching session.

The exposure time of the bleach will always be a maximum of 20 minutes in each of those sessions.

It’s crystal clear.


To make it even clearer, I’ll tell you some secrets to further protect your hair from the bleach action. The idea is for the damage to be as little as possible during those twenty minutes.


How to use the 30-volume bleach correctly on your hair

before applying it to the hair

Now that you’re clear about exposure times and how bleach works on your hair, here are my useful extra tips.


The scalp produces sebum during that time, which is a natural protector of hair fiber.


  • When preparing the bleaching mixture, add a few drops of coconut oil.

It adds extra protection to your hair and won’t interfere with the bleaching process.






What happens if it didn’t lighten your hair to the shade you want?

several bleaching sessions

You’ll need to bleach your hair again.

You can bleach your hair every three weeks. In the meantime, I advise you to deeply moisturize your hair.

You can use coconut oil, argan oil, or jojoba oil. You can also apply masks with shea butter or hydrolyzed proteins.

 Choose the one you like best, but don’t forget to moisturize your hair 


Do you want to know what shade you can achieve according to the number of sessions and the base color of your hair?

  • Very dark hair to achieve dark tones: 1 or 2 bleaching sessions
  • Dark hair to achieve medium tones: 2 or 3 bleaching sessions
  • Medium hair to achieve light tones: 3 or 4 bleaching sessions
  • Light hair to achieve very light tones: 1 or 2 bleaching sessions


In other words, if you want to achieve a very light blonde from black hair, you’ll need between 8 and 9 sessions.

So, where are those thirty minutes that many people are talking about?



The 30-volume bleach has to be on the hair for a maximum of twenty minutes. It doesn’t matter what base color you start with or what color you want to achieve.

If you leave it on longer, your hair won’t resist the powerful chemical reaction. It’ll burn and break.

Having said that, now it’s up to you. It’s your hair and your choice.

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