What does 40 developer do to hair?

Author: Mrs. Nelle Abshire PhD  |  Last update: Friday, November 28, 2025

40-volume developers, like the Keywest Professional Silver Sand Developer, contain 12% hydrogen peroxide. This concentration allows it to open the hair cuticle more aggressively, lifting natural pigments and making it an ideal choice for significant lightening or bleaching.

What happens if you just put 40 developer on your hair?

Damage Risk: The high strength of a 40 volume developer can cause considerable damage to the hair. It can lead to dryness, breakage, and an overall unhealthy appearance, especially if the hair is already compromised or previously colored.

Is a 40 volume developer too strong?

Strength of Developer: A 40-volume developer contains 12% peroxide, which is very strong and can lift hair color significantly. However, using such a strong developer can also cause damage to the hair.

How long do I leave 40% developer in my hair?

40 volume bleach is very potent and isn't supposed to be left in your hair for more than 10-20 minutes. If you have coarse or very dark hair, you can leave it a few minutes longer.

How many shades does 40 vol lift?

40 Volume (12%) Developer

A Volume 40 developer is only used for lightening and can lift up to 8 levels. It is recommended for use with a lightening cream or powder for those who want to achieve blonde results.

hair color developer explained- 10, 20, 30 & 40 volume | 2024

When should I use a 40 volume developer?

If you're looking to lighten your hair by three or more levels, 40 volume developer is the option for you. It's also a good choice if you have very resistant hair that's difficult to color. People choose 40 volume because it's strong enough to lighten even the darkest hair.

What happens if you use more developer than hair color?

Using too much developer can lead to over-processing, which means that the hair cuticles can get damaged, leaving the hair looking dull, dry, and brittle. Plus, the color won't turn out the way you want it to, and you might even end up with a funky, uneven color that looks like a unicorn threw up on your head.

Which is the strongest developer?

40 volume developer is the strongest level of developer, and we do not recommend it for at home use. Even with dark hair, it is easier and safer to do several rounds of lightning with a lower volume developer rather than try to lift your hair an extreme amount in one go with a higher volume developer.

What happens if I use 20 developer instead of 40?

Developer choice going lighter with regular color

Use 20 Vol if you are aiming for a 1-2 level lift (and if you have grey hair that needs covering). Use 30 Vol if you are aiming for a 2-3 level lift. Use 40 Vol if you are aiming for a 3 level lift and if the hair is particularly difficult to color.

How long should I bleach my knots with 40% developer?

Bleaching your knots for 30-60 minutes is what gave me the best results!

How many sessions to go from dark brown to blonde?

From a strand test, you should also get a better sense of how many sessions you'll need to make the full transition. For example, going from dark brown to light blonde hair may require three to four sessions.

What is the difference between a 20/30 and 40 developer?

A 10 Volume developer provides minimal lift, perfect for depositing color. A 20 Volume developer lifts hair by 1-2 levels, while a 30 Volume developer lifts by 2-3 levels. A 40 Volume developer offers the most significant lift, up to 8 levels, for dramatic color changes.

What developer to use to cover grey hair?

The standard developer for gray coverage is 20 Volume; however, 30 Volume and 40 Volume can also be used if the percentage of gray is low and additional lift is needed to achieve the desired result.

How damaging is 40 volume developer?

With its strength, a 40-volume developer comes with risks that must be managed carefully. Here are some key considerations: Potential for Damage: High peroxide levels can be tough on hair, potentially causing breakage, dryness, and split ends if not used correctly.

Which developer is best for dark hair?

10 volume developers contain 3% hydrogen peroxide. These developers are also called no lift developers because they only provide moderate lift to your cuticles, i.e., lift by 1 level. This developer is perfect for when you are going to color your hair a darker color than the natural shade.

Can developer mess up your hair?

Dryness and Damage: As mentioned earlier, higher volumes of developers can cause severe damage and dryness. If you use too much hair colour and developer, the excess peroxide can strip your hair of its natural oils, leaving it brittle and prone to breakage.

What happens if you mix conditioner with developer?

However, Halim warns that combining conditioner with permanent or developer-based dyes can disrupt the chemical reaction and oxidation process needed for permanent color, which may lead to uneven or inconsistent color.

Will 40 developer lighten hair without bleach?

Without bleach, the 40 volume developer will only deposit color and may lighten the hair slightly, but not enough to achieve the desired blonde or light color.

What does toner do to hair?

It doesn't completely alter your hair colour, but it helps you subtly manipulate the shade of brassy hair. Hair toners neutralise unwanted warm or brassy tones to help you achieve a shinier, healthier, more natural-looking shade.

What developer gives the most lift?

40 Volume. 40 volume developer can be used with permanent hair color and high lift color to give 3-4 levels of lift depending on the power of the color and the texture of the hair. Open-air processing such as balayage is ideal for 40 volume developer as it allows for maximum lift but the control of less heat.

Is higher developer more damaging?

Higher volume developers can be more damaging to the hair, so it's important to follow the instructions provided with the hair dye or bleach product.

What happens if you put grey hair dye on brown hair?

If your hair is brown, you may need to bleach it more than once before you apply the grey dye. It's important you get your hair as light as possible before you attempt to turn it grey – this will help ensure a more even tone and vibrant, all-over colour.

What happens if you put too much toner in your hair?

So, why has your hair become stained with hues of blue or purple? Well, you may have either over toned your hair, the toner is too strong, you've applied too much or your hair is very porous. Uh oh! Luckily, there are ways to reverse this!

How many shades does 30 vol lift?

While bleach opens up the hair cuticle more forcefully for intense lightening, a 30 volume developer on its own can still help to lift color by about two to three levels, depending on your natural hair color. This option is ideal if you want to avoid the harsh effects of bleach but still desire a lighter color.

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