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How Long to Leave Bleach in Hair and 8 Mistakes to Avoid

Hair bleaching can be a chore for someone with no professional styling experience. Does that sound like you? Not to worry! This piece will teach you all you need to know about the bleaching process: what you need, how to put bleach on your hair safely, how long to leave bleach in your hair, and what to expect. Ride with me!

What Is Bleach and How Does It Work?

Bleach is a chemical product that contains ammonia and hydrogen peroxide. When applied to hair, it’ll lighten its natural color. The process of bleaching is known as oxidation.

Close-up of nicely bleached hair.

Bleach can only work when it’s mixed with hydrogen peroxide. When bleach and hydrogen peroxide are mixed, they become an alkaline agent and soften the layers of the hair shaft known as the hair cuticle. (Hair cuticles make up the outer layer of a hair strand, protecting it. The hair’s cuticle is the only layer visible to us.

During oxidation, bleach breaks down and softens the melanin of the hair. First, the black/brown pigments are dissolved, then the red/yellow pigments follow. As a result, the hair becomes lighter, and the darker shades are lost. 

Bleaching Vs. Dyeing 

Materials needed to bleach hair.

Although bleaching or dyeing do the same thing to your hair — changes its color, their methods are different. Dyeing your hair will change its natural color. Bleaching your hair will also change its color, but it’ll remove it altogether this time.

So, while bleach changes your natural hair color by lightening it, hair dye changes it by coating the strands with whichever color you choose. On that note, dye is temporary, and bleach is a more permanent option.

Safety Measures Before Bleaching Your Natural Hair Color

Before you bleach your hair, it’s necessary to check if it’s in the proper condition. If you overlook this, you might face the risk of damaging your hair severely. Conduct an elasticity strand test to check if you’re good to go.

Here are a few tips:

  • To do this, gently stretch a piece or strand of wet hair. 
  • Your hair is healthy if it stretches well and returns to its original shape.
  • If it breaks, feels gummy, or does not return to its original shape, your hair elasticity is low. This is also an indicator of damage. 
  • If you find out your hair is damaged, we recommend that you don’t bleach your hair in the meantime. Instead, focus on treating your hair until it’s in a healthier condition to apply chemicals. Else, you might damage your hair even more.

Processing virgin hair or semi-virgin hair is much safer. If there’s over-processing damage, wait about two to three months before applying bleach to your hair.

We also recommend using oils as hair masks often. Coating your hair strands in coconut oil protects them from losing moisture during bleaching. You can apply the oil some hours before you bleach.

Container of coconut oil.

What Are the Steps to Bleaching Your Hair?

 How can you go about it now that you’ve decided to blonde up? Here are some steps to guide you!

1. Get Your Supplies Ready

To bleach your hair, you’d need these materials:

  • Bleach kit 
  • Old clothes and towel
  • Shampoo
  • Hair clips
  • Tinting brush
  • Plastic/Latex gloves
  • Plastic mixing bowl
  • Shower cap/ Plastic bag
  • Protein balancing conditioner
  • Toner

2. Protect Yourself 

While bleaching your hair, you’d need to protect yourself from stains. Wear an old shirt or cover your shoulders with an old towel to do this. You should also wear gloves to protect your hands and put a rag on the floor.  

3. Prepare Your Hair Strands

Girl looking at her bleached hair

Divide your hair into four sections. Ensure that there’s no styling product applied to your hair (rubbing coconut oil beforehand is fine). 

4. Mix and Apply

In your bleach kit, there’s a developer and a lightener. The lightener is the bleach powder, while the developer is the hydrogen peroxide liquid — the bleaching agent that activates the bleach.

To mix the developer and lightener, read the instructions on the product. It’s usually mixed with two parts developer and one part lightener. Use a plastic bowl and tinting brush for the mixture.

  • The general rule is to apply the bleach 1 or 2 inches away from the root. hair close to the scalp bleaches faster. You can always return to the root after you’re done with other parts, or you may choose to leave the roots unbleached. 
  • Apply bleach to hair by brushing through one-quarter of the back section of your hair. 
  • When finished with one quarter, clip it, move on to the second back quarter, and do the same. 
  • When you’re done with the back section, repeat the process with the front section till you’re done. 
  • Once your hair is coated, use a shower cap or a plastic bag to cover it. 

5. Wait

Once you’re done applying bleach to your hair, cover it with a shower cap or plastic bag and wait. Typically, you should not leave it on for more than 30 minutes. Later, we will explain how long to leave bleach in hair. 

6. Wash Your Hair

Once your hair is processed, wash with lukewarm water to eliminate the bleach. Apply shampoo and conditioner after. 

7. Tone

Don’t tone immediately after you bleach. Allow your hair to rest for 1-2 days before applying toner. Also, it’s common to discover warm tones in your hair after bleaching. If this happens, consider using a toner to even out the color. To tone the final color, substitute the bleach with toner and repeat the same steps above.

What Happens If You Leave Bleach in Too Long?

What happens if you leave bleach in hair too long?

Bleaching is a chemical treatment. Hence, keeping bleach in hair for too long can lead to a burned scalp and extremely damaged hair. Chemicals like hydrogen peroxide, persulfates, and alkalizing agents are found in bleach products. And these harsh chemicals can burn your scalp if left for too long. So, it’s important to know how long to leave bleach in your hair.

If the bleach starts to burn your scalp, wash it off your whole head immediately, whether it has stayed long in your hair or not. If you still feel pain and burning aside from the usual slight itching, reach out to your physician for advice.

Aside from burning the scalp, keeping bleach for too long can also lead to dry and brittle hair. When bleach penetrates through the hair shaft, it makes it porous or widely spaced. This causes a lack of moisture, resulting in brittle and damaged hair strands. 

How Long to Leave Bleach in Hair

Bleach mistakes to avoid

Knowing how long to leave bleach in hair before washing it off will help you get a satisfactory result. There are three main factors to consider before leaving bleach in hair:

  • Hair Color 
  • Hair Type
  • Developer Volume
  • Hair Color

Natural hair can be classified according to 10 levels. Level 1 is the darkest color, and level 10 is the lightest. To know how long you should have bleach in your hair, first find out whether you have lighter or darker hair.  

How Long to Leave Bleach on to Lighten Blonde Hair

Blond hair is around level 7. there’s no need to let bleach stay in blonde hair for so long. 15 to 20 minutes is best recommended. 

How Long to Leave Bleach on to Lighten Brown Hair

Brown hair is between levels 3-4, so you can leave bleach for 20-25 minutes before washing it off.

How Long to Leave Bleach on to Lighten Dark Hair

If you have black hair, your color level should be around 1 to 4. You can choose to apply bleach and leave it for about 30 minutes before washing it off. Dark hair contains dominant red and orange pigments, so if you don’t bleach them out enough, you might end up with your hair orange. Hair dyes might be a safer alternative if you don’t want to risk it. 

Hair Type

Sometimes, the best duration to leave bleach in your hair depends on your hair type. At the basic level, there are three hair types or textures: fine, medium, and coarse. 

How Long to Leave Bleach on to Lighten Fine Hair

Fine hair has a thin texture that processes faster and breaks easily. If you have this hair type, we recommend leaving bleach in for 10 to 15 minutes before washing. 

How Long to Leave Bleach on to Lighten Coarse Hair

Coarse hair is thick and more tolerant to styling products and processing. People with thicker hair can apply bleach and leave it for about 30 minutes before washing it off. 

Volume Developer 

Alongside color and texture, the volume of the developer/peroxide liquid is another factor to consider when bleaching your hair. Developers come in four volumes: 10, 20, 30, and 40. You may choose a volume developer depending on your hair type. 

How Long to Leave 10 Volume Developer on to Lighten Hair

A 10-volume developer can only lift your hair color by at least 1 level. This means if you have dark-brown or dark hair, it most likely will not make it significantly lighter. However, if a subtle change is what you want, you can go for it. 15-30 minutes is best recommended for this volume of developers.

How Long to Leave 20 Volume Developer on to Lighten Hair

A 20-volume developer would stop lifting after about 1-2 levels of hair color. It works well for people with dark-brown dark or dark hair who desire a lighter shade. If this is the desired lift, one can also leave bleach in the hair for 15-30 minutes.

How Long to Leave 30 Volume Developer on to Lighten Hair

If you want to lift your hair color by 3-4 levels, a 30-volume developer will do the trick. Maintain a waiting period of 15-25 minutes to avoid hair damage. 

How Long to Leave 40 Volume Developer on to Lighten Hair

For a high lift, a 40-volume developer is recommended. To avoid too much hair damage, one should not leave bleach in hair for more than 15-20 minutes.

Bleach Mistakes to Avoid 

Beautiful blonde hair.

Here are some common bleach mistakes you should avoid:

1. Not Doing Enough Research

Bleaching by yourself can be tricky. You’re not a professional hairstylist, so you need to research well before you consider putting bleach on your hair. Not researching enough can lead to mistakes like not getting your desired hair color or hair damage. 

To avoid such mistakes, find out enough information about the process. Know your hair color, type, and the type of hair bleaching products that’ll work best for you. 

2. Not Preparing the Hair

It’s necessary to have your hair in its best condition before bleaching it. This will bring out a better result and reduce damage. Always keep your hair and scalp moisturized, and avoid over-processing weeks before bleaching. 

3. Using the Wrong Tools

Avoid using the wrong tools and materials while bleaching. Protection is essential, so ensure you cover your body to avoid stains. Most importantly, never use metallic materials

4. Skipping Strand and Skin Tests

A strand test and a skin test will tell you how the main process will go and if the hair bleach you’ve chosen will work for you. It’s simple:

  • Make a small bleach mixture and rub it on the inside of your elbow or the back of your ear.
  • When it dries, check for allergic reactions like stinging and burning.
  • Test the mixture on a strand of hair to see the coloring process.

5. Bleaching Hair Alone

Mirrors are never a perfect substitute for family and friends. You’re not a professional colorist, so you may miss some spots and not correctly put the bleach on your hair. They can help you point them out.

6. Leaving the Bleach on for Too Long

Most people don’t know how long to leave bleach in their hair. Some believe the longer you leave bleach in your hair, the better the color will come out. This is hardly correct. Bleaching your hair for over 45 minutes will only create such damage as dryness and fallout.

7. Double Processing

Some people may be tempted to bleach again for shades lighter than the previous bleaching session. This usually happens when they fail to achieve the desired color at first. This is risky because it doubles the product’s toll on your hair. 

A single bleach alone causes dryness and dehydration. Multiple bleaching sessions will double this. So, it’s best to wait at least four weeks to bleach again. This will help it heal and recover from the drastic change from the previous bleaching session. 

8. Skipping Toner

Hair bleaching alone may leave your hair with a brassy color. You don’t want your hair to turn orange or end up having different shades. To remove this and neutralize the colors, you can’t avoid toning. Remember to wait for a day or two after bleaching to tone your hair. 

Final Words

Girl with bleached hair

Bleaching your hair by yourself will require some reasonable research. A mistake might be costly! We’ve done it all for you, so how about you try out these tips and tell us how it goes? We’d love to hear from you!

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