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How to Use 40 Volume Developer to Lighten Dark Hair

40 vol developer is an excellent way to lighten thick, dark, and coarse hair to light brown or blonde, and it can achieve up to 4 levels of lift. If you’ve never used a 40 volume developer to lighten hair, you’re in the right place.

In this article, we’ll explore how to use 40 vol developers when you want to lighten your dark hair and how to take care of it after.

What is a 40 Volume Developer?

40 volume developer

40 volume developer is a lightening agent that contains 12% peroxide. You can mix it with bleach to create a platinum blonde or with permanent hair color to lighten your hair while dyeing.

Developers work by lifting the cuticle layer of your hair. The higher the volume, the more the cuticle is lifted. This lifting is what lightens your hair.

Developers also help hair dye penetrate the hair shaft, causing the color to last longer and to be more vibrant.

When to Use 40 Vol Developer?

You can use a 40 vol developer on any hair as long as you do so carefully. The high volume isn’t recommended for those with naturally blonde hair color but works wonders for those with dark hair.

The darker and coarser the hair, the more challenging it is to lighten. You may also use a 40 volume developer when you want to remove or change hair you’ve previously dyed.

40 vol is excellent for eliminating semi-permanent hair dyes. It’s difficult to remove all color from your hair once you’ve treated it, but it isn’t impossible.

Ask a stylist about your options and hair type before applying multiple rounds of the developer to previously treated hair.

How to Use 40 Volume Developer to Lighten Hair

There are two ways to use a 40 volume developer to lighten your hair. One method is to use bleach, and the other is only to use the developer.

After a certain point in the process, the application is the same.

Tip: Do not wash your hair before you put the developer on. Your hair’s natural oils (like sebum) help protect your roots and cuticles from being stripped. Lightening hair that you haven’t washed in over 36 hours is the healthiest.

Gather Your Supplies

using 40 vol developer

You don’t need a lot for a 40 volume developer to lighten dark hair, but you need a handful of supplies at your fingertips. Here’s a quick list to get you started:

  • Bowl
  • Disposable gloves
  • Dye brush
  • Hair clips
  • Bottle of developer
  • Any bleach or color you’ve decided on

Mixing the Developer (Or Not)

Place a small amount of developer into the bowl and ready your brush. The remainder of this step only applies to people who want to mix their developer with bleach or hair dye.

Following the guidelines on the developer, bleach, or hair dye, mix the recommended amounts of the developer with either the bleach or dye. You can do this right in the bowl.

Beauty supply stores sell small plastic bowls if you don’t want to sacrifice a kitchen bowl.

You’ll know when you have the right consistency because it’s thin enough to spread but thick enough to cling to your hair.

Getting Started

How to Use 40 Volume Developer to Lighten Hair - Using the Developer

Using the hair clips, section your hair into manageable bundles. I typically divide my hair into four sections. The front left, front right, back left, and back right.

You can also use the clips to include or exclude sections of your hair. With gloves, apply the developer to your hair. Start with the ends before working your way up to your roots.

Give your roots about a half inch of space to ensure you don’t burn your scalp. You want to start at the ends because they take longer to process.

The Waiting Game

Leave the developer on for 15-20 minutes, then check the color. If you aren’t satisfied, check again in five minutes. Don’t leave it on longer than 30 minutes!

Rinse and Condition

Once time has expired, thoroughly rinse your hair in cool water before shampooing and conditioning. Gently towel dry – don’t blow dry it!

Aftercare of Hair for 40-Developer

You must take care of your hair after using a 40-volume developer. Here are a few ways to rehydrate your hair:

  • Wash your hair less often
  • Use a more potent conditioner (not a 2-in-1!)
  • Apply hair masks
  • Invest in hair oils
  • Don’t style your hair with heat
  • Wash your hair in cool water
  • Don’t expose your hair to chlorine
  • Trim hair frequently to reduce split ends

How to Dilute 40 volume Developer to 20?

Diluting your 40 volume developer to 20 vol is as easy as mixing your developer in a 1:1 ratio with water. The water will begin to break down the developer, so you can’t store the new mixture for very long.

How to Dilute 40 volume Developer to 20

If you need to dilute your developer, do it the same day you plan on treating your hair. It’s crucial to ensure you’ve measured correctly so you don’t leave the developer on for too long.

Whenever you dilute it, you should do a spot test on the end of your hair to see how long it takes and what color you achieve.

You can use 40 volume hair developer on any dark hair to lighten hair color and use it with or without bleach and hair dye. Incorporating aftercare into your hair routine is crucial to ensure your roots and cuticles stay healthy.


If you aren’t 100% sure about a 40-volume developer to lighten dark hair? Here are some of the most common questions with answers.

What will a 40-volume developer do?

A 40-volume developer can give you up to 4 levels of lift and is ideal for a super platinum blonde. It can lighten dark hair and strip hair of semi-permanent hair coloring. Your hair will be more fragile and have split ends and breakages.

Is a 40-vol developer stronger than a 30-vol developer?

Yes, a 40 volume developer is stronger than a 30 volume developer. A 30 vol typically gives you three levels of lift in color, while 40 will provide you with four.

How long can I leave 40 developers in my hair?

You should never leave 40 developer in your hair for more than 10-20 minutes.

If you have thicker, darker, or coarser hair, you can leave the developer on for longer in increments of five minutes. It should never be left on longer than 30 minutes at a time, regardless of your hair type.

Can 40 volume developer bleach my hair?

Yes, 40 volume developer can lighten your hair. You can mix bleach with the developer before applying it to your hair.

Can 40 volume developer cause hair loss?

40 vol developer can cause hair loss if you don’t perform the proper aftercare hair treatments or apply the developer directly to your scalp or roots of your hair.

You should never apply 40 volume to your roots, as this can kill your hair and cause issues when it tries to grow back.

How much 40 developer do I need to mix with bleach?

Whenever you mix developer with bleach, you want to follow a 2:1 ratio, developer to bleach. For example, if you use 6oz of the developer, you’ll want 3oz of bleach.

Do I need toner with 40 volume developer?

You don’t need to mix toner in with the 40 developer. Mixing toner with a high-power developer can weaken the developer, effectively eliminating the purpose.

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