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How Long to Leave Bleach in Hair (20 Vol) | Expert Tips

Wondering how long to leave bleach in hair (20 vol)? It’s really important to get the timing right to avoid damaging your hair. We’ll show you this plus tips to get the best results in our quick guide!

How Long to Leave Bleach in Hair (20 Vol Developer)

Image showing how long to leave 20 vol bleach in hair

Michelle Aleksa/Shutterstock

You may know how to bleach your hair, but the most important part of the process is timing. You’ve got to get it just right and continually check your hair’s progress at regular intervals along the way. 

If you leave bleach on your hair too long, you will permanently damage your locks and can even lose hair in the process. If you don’t leave it on long enough, you won’t achieve the lift you want and may get uneven, patchy results. 

The trick is using 20 volume developer in your bleach mixture because it doesn’t take long to process and isn’t as damaging for hair as higher-volume developers. It’s the mildest option for lift (instead of depositing color, like a 10 volume developer does).

It contains only 6% peroxide, while harsher options contain 9% (30 volume) and 12% (40 volume) peroxide. If you plan to use this milder developer for a less-damaging DIY bleach sesh, you need to know exactly how long to leave bleach in hair with 20 vol in the mix.

Find the detailed answer for a range of different hair scenarios – fine, coarse, blonde, dark, and damaged – in this quick guide. Or check below to get the short answer! 

The Short Answer

When it comes to how long to leave bleach in hair (20 vol), it typically takes anywhere from 15 to 30 minutes to fully lift your hair color 1-2 levels. 

Blonde hair may lift 2 levels in as little as 10 minutes when you use 20 volume developer, while darker hair may take closer to 20 or 30 minutes to achieve 1-2 levels of lift with 20 vol developer. You should never leave bleach mixed with 20 vol developer on your hair for more than 30 minutes.

What Does 20 Vol Developer Do?

How long to leave bleach in hair 20 vol developer

It’s easier to understand how long you can leave bleach in your hair when you know what developer is doing in the mix in the first place. You mix developer with bleach to either deposit or lift hair color.

And the developer volume you choose has a lot to do with how long your hair will take to process and finish lifting. Developer’s role in the bleaching process is an important one.

Its job is to swell and lift the plate-like cuticle cells on the outside of your hair strands. This allows bleach to make its way into hair strands and lighten your existing hair color. 

Should You Use 20 Vol Developer?

But not all developers have equal cuticle- and color-lifting power. The weakest developer, 10 volume, is only used to deposit color and won’t lift because it contains only 3% peroxide.

That small amount of peroxide barely raises hair cuticle cells, so it’s not enough to make the color lighter – only to deposit new color into the strand. For at-home bleaching, 20 volume developer is the most popular choice.

It’s stronger than 10 volume and contains twice as much peroxide (6%) but is still relatively gentle on hair. It is the mildest developer option you can use for lift (i.e., lightening the hair color).

You can achieve 1 to 2 levels of lift when you use 20 vol developer in your bleach mixture. For 3-4 levels of lift, you’ll have to use 30 or 40 vol developer. You have to carefully monitor your hair’s lifting progress with these harsher options and are more likely to damage your hair.

For these reasons, we recommend using only 20 volume developer when bleaching your hair at home. Leave the 30 and 40 volume developers to a professional if you need more than 2 levels of lift. 

How Long to Leave Bleach in Hair With 20 Vol Developer

Bleaching your hair is a time-sensitive mission. You can’t just guess at processing times – you have to be precise and start checking your hair’s progress at the 10-minute mark.

If you’re using 20 volume developer in your bleach mixture, you’ll get the most lift and best results when you time it properly. Determining how long to leave bleach in hair with 20 vol developer starts with taking a look at your hair’s color and characteristics.

You’ll leave bleach + 20 vol developer on longer if you have dark or coarse hair. It may only take 10 minutes to fully process if you have blonde or very fine hair. Here’s a look at how long you should leave bleach in different types and colors of hair with 20 volume developer:

  • Blonde hair: Process 10-20 minutes
  • Fine hair: Process 10-15 minutes
  • Medium hair: Process 15-20 minutes
  • Dark hair: Process 15-30 minutes
  • Coarse hair: Process 15-30 minutes

The finer your hair is, the less time it will take to process and lighten up to 2 color levels. You may find that your hair is fully lightened after 10 minutes of processing time with 20 volume developer if you have very fine (or blonde) hair. 

The coarser your hair is, the more time it will take to lighten with 20 volume developer. You should start checking it at the 15 minute mark if you have medium or coarse hair. It may take up to 30 minutes to process fully if your hair is very coarse (or dark). 

Bleaching With 20 Volume: FAQs

Still looking for info on bleaching your hair with 20 volume developer? Get answers to your questions here. 

What happens if you just put volume 20 in your hair? 

If you use 20 volume developer to lighten your hair without bleach, it will lift your hair color by about 1 level.

So if you’re starting out as a level 6 dark blonde, 20 volume developer will lighten your hair color to level 7 medium blonde. You can achieve more lift (up to 2 levels) by mixing 20 vol developer with bleach. 

Can I leave bleach on my hair for 20 minutes?

You can leave bleach on your hair for anywhere from 10 minutes to 30 minutes. Set a timer for 10 minutes after applying the bleach mixture to your hair. Lift the shower cap and check your hair’s lifting progress.

If it’s not as light as you’d like, leave it for another 5 minutes before checking again. If it seems to be lifting slowly (or you’re starting with a darker hair color), you can leave it on for a maximum of 30 minutes.

How many levels will 20 volume lift? 

You can achieve 1-2 levels of lift with 20 volume developer and bleach. So if you’re starting out as a dark blonde (level 6), you could potentially get to light blonde (level 8) by using 20 volume developer with bleach.

If you need to lift your color more than 2 levels, you’ll have to use 30 volume or 40 volume developer (not recommended for at-home use). 

How long should I wait between bleaching sessions?

The longer you can wait before bleaching your hair again, the better your hair will fare. But you can bleach your hair again after about 2 weeks without causing too much damage.

Don’t bleach again so soon if your hair feels or looks damaged after the first bleaching session – wait a month or two to give your strands time to heal. 

What ratio of bleach and developer should I use?

Your bleach/developer ratio can be tweaked to make the mixture the consistency you like working with best. Most professionals use a 1:1 ratio with equal parts bleach powder and developer – this gives you a thick, gravy-like consistency that won’t drip during application. 

Some like the runnier consistency and easier “paintability” of a 1:2 ratio with 1 part bleach to 2 parts developer. It allows you to apply bleach quickly to large sections and thoroughly saturate hair fast. Experiment with both ratios to see which consistency you prefer! 

Things to Consider

Now that you know how long to leave bleach in hair with 20 volume developer, check out a few more things to consider to get the best results from your DIY bleaching session. 

  • Start checking your hair at the 10-minute mark. Even if you think your hair will take a lot longer to fully process, you need to start checking your hair at the 10-minute mark. Lift your shower cap and peek at the color of your hair. You’ll be able to better track the color progression through the different levels of lift. Remember that 20 volume can lift your color 2 levels max, so don’t expect a transition from dark brown to light blonde. This will help you avoid overprocessing your hair and causing damage. 
  • Very dark hair may not lift enough with 20V. While 20 volume developer is strong enough to lift light colors as much as 2 levels, it struggles to lift dark hair. You may get only one level of lift with 20 vol if you have black or dark brown hair. In this case, you may need a 30 or 40 volume developer instead. These harsher developers can give you 3-4 levels of lift, so they’re a must for extremely dark hair but not recommended for at-home use due to their higher damage potential. 
  • Make sure your hair is healthy enough to bleach. If you’ve recently bleached your hair (within 2-4 weeks) or feels damaged, it’s best to postpone bleaching for a while – even with 20 vol developer. It’s only safe to bleach your hair when it’s at its healthiest. If you bleach when your hair has any symptoms of damage or has recently been subjected to a harsh chemical treatment (like bleach, color, perm, etc.), wait 2 weeks or more before bleaching to avoid unnecessary damage. 
  • Don’t bump up the volume. If you’re not a pro, don’t mess with 30 or 40 volume developer, period. With 9-12% peroxide, these developers make the bleach process quickly and leave very little room for error. While the process time may be faster, the potential for serious damage outweighs the benefits for at-home use. 
  • Don’t forget to prep before bleaching. Taking a few steps to prepare before bleaching can help you avoid a mess and make the process easier. Put on an old t-shirt and wrap a white towel around your neck. If you can, deep condition your hair with coconut oil or a deep conditioning treatment the night before bleaching. And to ensure you’ll be able to get the results you want with 20 volume developer, do a spot test on a hidden small section of hair before you bleach to see how much lift you’ll get. 

So, How Long Do You Leave Bleach in Hair (Vol 20)?

Stay watchful and be precise with your timing when you bleach. Going even one minute over the suggested processing time can be the difference between ending up with healthy, lightened hair and straw-like, damaged hair.

So set a timer as soon as the bleach is on and remove it promptly when you’ve reached the right level of lift! Bleaching with 20 volume developer is the best option if you plan to bleach your own hair at home.

As long as you leave it on for the right amount of time – anywhere from 10 (fine or blonde hair) to 30 minutes (coarse or dark hair) – you should be able to safely achieve up to 2 levels of lift without damaging your hair in the process.