How To Decide What Developer To Use With Bleach

I want to start this post off stating that I don’t recommend bleaching your hair yourself. I know that this may sound conflicting with writing a post about what developer you should be using, but it’s true. I’ve seen way more instances that have gone wrong than have gone right. So much, that I have an entire post dedicated to explaining why you shouldn’t bleach your hair yourself, and you can find that here.

All that being said, I know that there are some of you that are going to do it anyway, and I’d rather share my knowledge for you to have the best chances of success possible. I also want to share my knowledge for aspiring hair stylists so that they can learn and grow as a stylist themselves.

So in this post I’m going to explain how bleach works with developer, as well as how to decide what developer strength you should use. Keep in mind that this post is solely related to using bleach, not regular hair color or toners. If you’d like me to make a post talking about those topics, leave a comment letting me know below.

How does bleach work with developer?

First it’s important to understand how bleach works with developer, before choosing what developer strength we should use.

Developer is hydrogen peroxide. The different strengths of developer are different concentrations of the peroxide. Developer comes in 6 volume, 10 vol, 20 vol, 30 vol, 40 vol, and even 50 vol strengths.

It is extremely important to note that when using developer with bleach, the different strengths are referring to the SPEED at which the bleach will work. NOT the intensity. There are professional hairstylists that don’t even realize this distinction, but it is extremely important.

The role of the developer is to open the cuticle (outer layer of the hair that resembles fish scales) to allow the bleach to enter into the cortex (middle layer of the hair that contains the color molecules) and activate the bleach. The bleach will then begin the process of decolorization. This means that it is removing or stripping the color molecules from the cortex of the hair.

How do I know what developer to use with bleach?

When choosing what developer strength you should be using with your bleach, there are a number of factors to consider. Unfortunately there isn’t one “right” answer to this question, and I never use one developer strength entirely in one service.

In fact, I often times use multiple developer strengths inside of a single foil. This is so I can get all of the hair to process the same, no matter what the starting canvas was. You definitely don’t want to use the same strength developer on the natural hair color as well as the previously lightened hair. This will cause breakage to those previously lightened pieces.

Watch my Youtube Video below where I demonstrate the different strengths of developer:

What happens if I choose the wrong developer strength?

The strength of the developer equals the speed at which the bleach works. So this means that if you choose a developer strength that is too high, then the hair can become over-processed and damaged very quickly.

High developer strengths typically blast open the cuticle super fast, which can be damaging in itself even if the hair doesn’t become over-processed. Those scales on the cuticle may not want to lay down properly after this and the hair will appear frizzy, lack moisture, as well as not hold onto hair color well.

Bleach typically stops processing after 55 minutes to an hour. So if you choose a developer strength that is too low, then the hair won’t process fast enough and will likely be rinsed while it is still yellow. Unless of course you reapply more bleach, but we’ll talk more about that later.

Continuously mix new bowls of bleach

The proper way to use bleach is to start with a lower volume of developer as you’re starting the application, and increase the developer as you move through the hair. This is so you have even processing throughout the hair.

You don’t want to have to rinse the first foils you put in prior to the last foils being finished. So to avoid this, you start with a low volume and increase throughout. I start off with 20 grams of bleach and increase the developer when I run out and need a new bowl.

You can also do this by increasing the developer with each section you come across. So for the nape of the hair you start with 10 volume, then as you move your way towards the crown you switch to either 15 volume (equal parts of 10 volume and 20 volume) or 20 volume developer. Then as you move to the sides, 20 volume or 30 volume developer.

The rate at which you increase should be dependent on the speed at which you work. If it takes you over an hour to apply, you’ll want to increase gradually.

Factors to consider

Below I’m going to list out the factors that you need to consider when choosing what developer to use with your bleach. Take each of these factors into consideration when choosing what developer strength to start with.

1. Condition of the hair

The condition of the hair plays a big role in deciding on if you should even be bleaching the hair, let alone what developer to use. If the hair is not in good condition, then you either shouldn’t bleach it at all or only use a low developer.

You may choose to use a higher developer on the hair closer to the root, with a lower developer on the ends because that hair is more damaged

To learn about determining the condition of your hair, see my post here.

2. Speed of application/time allotted for service

If you aren’t a professional or are inexperienced, the time it will take you to apply the bleach will likely be much longer than a skilled professional. So this means you’ll want to start with a much lower volume of developer than what I would use if I were highlighting your hair.

As I mentioned earlier, you’ll want to increase the developer strength throughout the application to ensure even processing. But if you can apply the bleach very quickly, then this isn’t necessary.

It’s also important to mention that as a hairstylist, sometimes you only have a specific allotted time to accomplish a service. This means that you need to make sure that the bleach processes in the correct amount of time that is scheduled for the appointment.

There may be instances where you need the bleach to process quickly because the client booked the wrong service. In this instance, you’ll want to use a higher strength developer.

3. Hair type

The texture of the hair is what determines the diameter of the individual hair strand. If the hair is fine, it will process much quicker than if it is coarse, so a lower volume of developer should be used with fine hair.

And if the hair is very thick (meaning you have a lot of hair), it will likely take you twice as long to apply the bleach than if the hair was thin. Because of this, you’ll want to start with a lower volume with thick hair, so that the first foils applied will not over process by the time you finish the application.

To determine the hair texture see my post here, and to determine the hair density see my post here.

4. Is the hair color treated or virgin?

Color treated hair takes much longer to decolorize than virgin hair does. So if the hair you’re working with has been previously colored with permanent hair dye, then you’ll need to use a much stronger developer strength.

This is because permanent hair dye color molecules are made to permanently alter the cortex of the hair. Bleach is the only thing that will remove them (regular hair dye will not). It often takes longer to decolorize safely, and oftentimes needs to be done in multiple sessions.

The quality of the permanent color also makes a big difference, and if it was a progressive dye or not. I talk a little about progressive dyes in my post here about box dye. Most box dyes are progressive, so it takes significantly longer to remove from the hair than professional hair color or virgin hair. Sometimes the hair can only be lifted to a certain extent before the hair breaks off.

This is a tricky one because if box dye was used, the hair is at more risk for damage so a lower volume is better. That being said, colored hair typically takes longer to lift, so a higher developer will get you further. This is why as hairstylists we hate box dye so much!

In this case, use your judgement based on the condition of the hair.

5. Are you adding Olaplex or another bond builder?

Olaplex is a brand of bond builder. Bond builders are chemicals made to strengthen the hair as it bleaches it. This was a ground breaking invention in the hair world, and enabled us to go to much further lengths of decolorizing hair without damaging it.

That being said, bond builders slow the processing time. So if you are using a bond builder, you typically need to increase the strength of the developer. Always read the instructions on all of the products you’re using, and if your bond builder slows processing time, they will tell you to increase the developer strength.

How to get better lift without using a higher developer strength

I always recommend taking a low and slow route when bleaching the hair. This is because you can cause irreversible damage to the hair if you over process it. The worst that will happen with using too low of a developer, is the need to reapply more bleach.

My best recommendation is to start very low with your developer strength, starting at 6 or 10 volume. I never recommend starting above 20 volume with bleach. Then, after you finish your last section of application, go back and check your first section applied.

If you need to, you can now mix up a new bowl of bleach and apply it to the hair. This will restart the processing time of 55 to 60 minutes, meaning the hair will continue to process up to the desired level.

This may take longer to get to the desired results, but it is definitely the safer way to go.

Developer With Bleach Conclusion

Developer is hydrogen peroxide that activates bleach to decolorize (or lighten) the hair. The developer strengths are what determine the speed at which the bleach will work. They come in 6, 10, 20, 30, 40, and 50 volume options.

Choosing the wrong developer strength could cause the hair to become over-processed and break off, or under-processed and not up to the desired color.

It is best to start with low developer and increase the strength as you move through the bleach application. Low and slow is the safer route.

The 5 factors that will help you determine what developer strength are:

1. The condition of the hair
2. The speed of application/time allotted for service
3. The hair type
4. If the hair is color treated or virgin
5. If you’re using a bond builder

To increase processing without using a higher developer, re-apply a new mixture of bleach after the bleach processing time is up (usually around 1 hour). The bleach will begin processing again to get up to the desired shade.

If you have any further questions, leave them for me in the comments! And make sure to subscribe below to make everyday a good hair day!