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How Long To Leave Bleach In Hair? Here’s The Answer In 2024

Cindy Scott

Updated on - Written by
Medically reviewed by Jennifer Olejarz, Nutritionist & Health Coach

how long to leave bleach in hair
Answering the burning question of how long you leave bleach in your hair comes down to meeting your hair’s specific needs. Photo: HelloDavidPradoPerucha/Freepik

As summer kicks off, many of us are looking for ways to get a lighter, sun-kissed glow in our hair. However, figuring out the answer to the question “How long to leave bleach in hair without damaging your hair?” can be tricky. Striking that perfect balance between blonde hair and maintaining hair health is key.

Read on to learn how long to leave bleach on hair and ways to deep condition hair after bleaching. Perfecting your bleaching time can help you get your dream summer hair while keeping your locks happy and healthy.

How Long To Leave Bleach In Hair?

How long should you leave bleach on your hair? While the processing time generally ranges from 20 to 45 minutes, closely monitoring color development during bleaching is crucial. Leaving bleach on for too long can lead to over-processed and damaged hair.

Moreover, the amount of time you leave bleach on your hair depends on many factors, such as:

  • Current hair color.
  • Desired level of blonde.
  • Bleach product used.

What Is Hair Bleach?

Hair bleach is a chemical product[1] designed to lighten your natural hair color. It typically has ingredients that break down melanin,[2] or the color particles, inside the strand of hair. The most common bleaching ingredients are:

  • Hydrogen peroxide.
  • Ammonia.
  • Persulfates.

Hair bleach can be used for techniques like highlights or full-head bleaching. It comes in powder or cream forms that can be applied by a professional hairstylist or at home. 

How To Know When It Is Time To Remove Bleach

Maybe you are asking yourself, how long should I leave bleach in my hair? Luckily, here are a few things that can help you learn the ideal bleaching time for your hair. 

Color Development

Monitoring your color development during bleaching is vital to get the best results and avoid mishaps. As the bleach works its magic, the color will progress through various stages. Try checking your hair at least every 10 minutes so you know when to stop. 

Hair Condition

Regularly checking the hair’s condition helps determine the optimal timing for bleach removal. During the bleaching process, excessive dryness, brittleness, or breakage can occur. Quickly remove bleach if any signs of adverse reactions happen.  

Factors That Affect Bleaching Stages

Factors That Affect Bleaching Stages
There are several factors that affect the bleaching stages. Photo: Freepik

Several factors can influence the stages of hair bleaching:

Natural Hair Color

Your natural hair color helps determine how many bleaching stages are needed to get the blonde level you want. 

Bleaching removes the natural melanin in the hair strands, which takes more time and effort for dark hair. But people with lighter hair colors, such as blonde hair or golden brown hair, may need fewer bleaching stages for the desired level of lightness. 

Hair Type And Texture

Hair type and texture significantly impact bleaching stages in the hair-lightening process. 

  • Fine or thin hair may bleach more quickly than coarse or thick hair. Thinner hair strands are smaller in diameter with fewer cuticle layers[3] allowing the bleach to penetrate more easily. This results in faster color change. 
  • Coarse hair or thick hair may require more time and multiple bleaching stages to achieve the desired lightness. The density and texture of the hair may affect how evenly the bleach spreads, requiring additional care and attention to avoid patchiness or uneven color.
  • Curly or tightly coiled hair may have more resistance to the bleaching process due to the structure of the hair strands, requiring longer processing times or more potent bleaching formulations. 

Bleach Strength And Developer Volume

The bleach’s strength and the developer’s volume impact the stages of the bleaching process. 

Bleach strength is the potency of the bleach, while the developer volume indicates the concentration of hydrogen peroxide solution. Volume 10, 20, or 30 developers are commonly used to lighten hair shades. The higher numbers are used to lighten dark brown or black hair. 

Stronger products can increase the risk to your hair. To determine how long to leave volume 30 bleach on hair, check the progress every 5-10 minutes. Limiting the bleaching time to 30 minutes may help reduce risks and save your lovely locks.

Application Technique

The application technique can impact the stages and overall outcome, resulting in different color lift and distribution degrees. 

For example, applying bleach with foil or using a highlighting technique can create dimension with lighter strands while maintaining a natural look. On the other hand, evenly applying bleach all over the hair can lead to an overall blonde and more consistent result. 

Proper application technique, careful monitoring, and timing are a dynamic trio to help prevent damage while lightening your locks. 

Hair Condition And Health

Healthy, well-maintained hair responds better to bleach and withstands processing times with little damage. Damaged hair is more susceptible to over-processing, leading to breakage, brittleness, and uneven color results. 

It’s important to assess the condition of your hair before bleaching and take necessary precautions. A deep conditioning treatment or another product to repair hair health can help improve and restore hair before bleaching. 

Professional Bleaching

While DIY options may be tempting, seeking the help of hair professionals has its benefits too. Many salons offer a bleach bath that can reduce the steps and time needed to lighten hair. A bleach bath may not lighten hair as much as other bleaching techniques but can give your hair a slight, sun-kissed look. A hair stylist can evaluate your hair type and decide how long to leave a bleach bath on your hair.  

What Happens If You Leave The Bleach On For Too Long?

Leaving bleach on your hair for too long can severely damage your hair. As bleach breaks down the hair’s natural pigment,[4] these things can occur:

  • The hair cuticle becomes more porous and spongelike.
  • The hair shaft becomes swollen.
  • There is increased brittleness due to porosity and swelling.

Over-bleached hair can appear dry, frizzy, less shiny, or patchy in color. 

Common Mistakes To Avoid When Bleaching Hair At Home

When bleaching your hair at home, it’s important to avoid these common mistakes:

  • Not conducting a patch test[5] — a hair dye or bleach mixture may cause an allergic reaction, so a patch test is necessary.
  • Incorrectly measuring and mixing bleach — proper measuring and mixing can help get the blonde you want without ruining your hair.
  • Overlapping the bleach — applying bleach on previously treated hair can result in over-processing. Avoid overlapping the bleach onto already lightened sections, and focus on new growth instead.
  • Using the wrong developer strength — different hair types and desired results require specific developer strengths. Too strong of a developer can lead to excessive damage, while a weak developer may not give sufficient lift.
  • Neglecting hair conditioning and aftercare — bleaching can dry out and damage your hair. After bleaching, use a deep conditioning treatment or a nourishing hair mask to help restore moisture in your dry hair.

Ways To Take Care Of Your Hair Post-Bleaching

Ways To Take Care Of Your Hair Post-Bleaching
Use gentle hair care products to take care of your hair after bleaching. Photo: Freepik

Proper hair care after bleaching is a must for stronger, healthier, more vibrant hair. Here are some essential tips for caring for your hair after bleaching:

  • Moisturize and hydrate — bleaching can strip the hair of its natural moisture, so deep conditioning treatment or using a hair mask weekly can be helpful to restore moisture and nourish your hair.
  • Minimize heat styling — use blow dryers, curling irons, and flat irons as little as possible, and protect hair with a heat protectant spray. 
  • Avoid harsh chemicals — after bleaching, avoid chemical treatments, such as perming, relaxing, or coloring, to allow your hair time to recover and regain strength.
  • Protect from the sun — UV rays can damage bleached hair and cause color fading. Avoid extra damage by wearing a hat or using UV-protective hair products. 
  • Use gentle hair care products — choose sulfate-free shampoos or purple shampoo and conditioners specially designed for color-treated or damaged hair.
  • Consider adding collagen — a collagen supplement can help support[6] healthy hair, especially after damage caused by bleaching.

Remember, everyone’s hair is unique, so take some time to understand your hair’s needs. Consistent and gentle hair care practices will help strengthen your hair and maintain your beautiful locks.

Conclusion

Answering the burning question of how long to keep bleach in hair comes down to meeting your hair’s specific needs. Hair type, color, and condition help determine how long bleach should stay on your hair.

Bleaching comes with risks, like drying out your hair or ruining your color. Luckily, you can follow our tips to minimize any damage. Combining knowledge, proper techniques, and regular hair care lets you enjoy the benefits of hair bleaching while keeping your locks luscious and healthy.


+ 6 sources

Health Canal avoids using tertiary references. We have strict sourcing guidelines and rely on peer-reviewed studies, academic researches from medical associations and institutions. To ensure the accuracy of articles in Health Canal, you can read more about the editorial process here

  1. Guerra-Tapia, A. and E. Gonzalez-Guerra (2014). Cosméticos capilares: tintes. [online] 105(9), pp.833–839. doi:https://doi.org/10.1016/j.ad.2014.02.004.
  2. Mostert, A.B. (2021). Melanin, the What, the Why and the How: An Introductory Review for Materials Scientists Interested in Flexible and Versatile Polymers. [online] 13(10), pp.1670–1670. doi:https://doi.org/10.3390/polym13101670.
  3. Baltenneck, F., Genty, G., Elias Bou Samra, Richena, M., Harland, D.P., Clerens, S., Leccia, E., M. Le Balch, Doucet, J., Michelet, J.-F. and Commo, S. (2022). Age-associated thin hair displays molecular, structural and mechanical characteristic changes. [online] 214(4), pp.107908–107908. doi:https://doi.org/10.1016/j.jsb.2022.107908.
  4. Guerra-Tapia, A. and E. Gonzalez-Guerra (2014). Hair Cosmetics: Dyes. [online] 105(9), pp.833–839. doi:https://doi.org/10.1016/j.adengl.2014.02.003.
  5. Lee, H., Kim, W.-J., Jun Suk Kim, Kim, H.-S., Kim, B.-G., Kim, M.-B. and Ko, H.-C. (2016). Patch tests with commercial hair dye products in patients with allergic contact dermatitis to para-phenylenediamine. [online] doi:https://doi.org/10.4103/0378-6323.186495.
  6. JDDonline – Journal of Drugs in Dermatology. (2022). A Six-Month, Randomized, Double-Blind, Placebo-Controlled Study Evaluating the Safety and Efficacy of a Nutraceutical Supplement for Promoting Hair Growth in Women With Self-Perceived Thinning Hair – JDDonline – Journal of Drugs in Dermatology. [online] Available at: https://jddonline.com/articles/a-six-month-randomized-double-blind-placebo-controlled-study-evaluating-the-safety-and-efficacy-of-a-S1545961618P0558X/
Cindy Scott

Medically reviewed by:

Jennifer Olejarz

Cindy Scott is a registered dental hygienist, fitness coach and freelance writer, with more than 20 years of health and medical experience. She is passionate about overall health and wellness as it connects throughout to the whole body. Through writing, she seeks to share knowledge and connections with others to give them the best overall health possible. Keeping smiles and bodies healthy, and HAPPY!

Medically reviewed by:

Jennifer Olejarz

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