How Long To Leave Bleach in Hair

After working in the hair business for many years, hair bleach is something I know quite a lot about. Bleaching your hair is a delicate process and should be done very carefully, preferably by a hair care professional, to avoid potential damage. If left on too long, you run the risk of some serious hair damage, but if you don’t leave the bleach on long enough, your desired color outcome may not be achievable. Bleach is an amazing coloring tool when used properly.

When bleaching your hair, the maximum amount of time that the bleach should be left on your hair is 30 minutes. Depending on your hair type, this time can vary. If your hair is blonde or very fine, 10-15 minutes is all you will need. If you’ve got dark or coarse hair, bleach can be left on for closer to 30 minutes. The timing also depends on if your hair was previously colored or bleached and your desired color goals.

What happens if you leave bleach in your hair for too long?

If you leave bleach on your hair too long, the results can be pretty terrible. Bleach is an aggressive product and can do serious damage, like creating brittle and broken strands and destroying your hair shaft in the process. This creates irreversible damage that will only be corrected after your hair grows out and regenerates.

What damage does bleach do to your hair?

Overall, your hair becomes weaker after bleaching. Bleach makes your hair strands very porous, leaving your hair very dry, as well. Another danger relative to hair bleach is the loss of keratin, a type of protein found in your strands. Keratin creates your hair’s structure and without it, your hair can become brittle and unruly.

How should you care for your hair post-bleaching?

  • Use high-quality salon-grade shampoo and conditioners meant for colored and bleached hair
  • Make sure the shampoo you choose is sulfate-free, as sodium lauryl sulfate or sodium laureth sulfate are power degreasers that are too harsh for your bleached hair
  • Add hair masks and hair oil to your hair care routine to help keep your strands hydrated
  • Brush your hair gently and only comb when it is wet—brushing too aggressively after bleaching will cause breakage. 
  • Use a thermal protectant spray when you use heat styling tools
  • Leave-in conditioner should be your new best friend. Follow label directions for use and look for products that advertise moisture and keratin-building properties.
  • A purple-tinted shampoo can help to remove brassiness if you used bleach to lighten your hair to a blonde shade. Follow the shampoo’s specific instructions for use.
  • Use hair sunscreen or wear a hat when going out into the sun

What should you not do after bleaching your hair?

  • Avoid using heat-styling tools on your hair for three weeks, but in general, air-dry your hair whenever possible
  • Avoid aggressive brushing
  • Avoid shampooing your hair for at least 72 hours after any bleaching appointment in order to allow the cuticle layer to fully close, which will help with maintaining your color longer
  • Avoid chlorine, this means staying out of the pool. Chlorine can make your hair even weaker and also alter the color of your freshly bleached locks. If you intend to swim, rinse your hair with cool water before you go for a swim and rinse again immediately after. 
  • Avoid using hair elastics that put a lot of stress on your delicate strands

How soon after bleaching hair can you bleach again?

Frequent bleaching can cause a lot of damage over time. The American Academy of Dermatologists recommends people wait 8-10 weeks between bleaching sessions. If you’re doing your hair yourself, make sure you are only applying bleach to your roots and new growth. Avoid re-bleaching your whole head at all costs, as this will cause extremely weak strands and breakage. 

How does bleach lighten hair?

Bleach is a very harsh product and should always be used with caution. It “dyes” the hair by actually dissolving the existing color. It achieves this due to its ability to open up the hair cuticle. The oxidative agent penetrates the hair cortex and dissolves the hair’s natural melanin. 

The two most common types of bleach are hydrogen peroxide and ammonia. They’re the most common types because of how effective they are, but they are also unavoidably damaging, which is why it’s best for the health of your hair if you allow a professional to color your hair.

Do you use hot or cold water after bleaching your hair?

After bleaching your hair, it’s best to wait to wash it for 72 hours. When it’s time to wash, however, it is best to use cool-lukewarm water in order to prevent your hair from drying out even more. If you’re washing with hot water, it can make your hair weak and brittle. The first wash at home after you’ve had your hair bleached should be with as cold water as you can handle because this will help keep the hair cuticle closed.

Is it safe to bleach your hair while you are pregnant?

If you’re expecting, you may be curious as to whether it is safe to bleach your hair. Good news: Hair bleaching products are likely safe to use during pregnancy, as the bleach does not penetrate your skin. Whether you’re bleaching at home or in a salon, make sure it is applied in a well-ventilated area, you’re wearing gloves (if self-applying), and you wait until at least the second trimester for extra precaution.

Will my hair turn yellow if I bleach it?

When bleaching your hair, you might be concerned if it looks orange or yellow-tinted. From experience in a salon, that’s where a toner comes into play. Bleach takes the color out of your hair and toner works to shade it to the appropriate shade. Often though, when done at home specifically, orange and yellow tints primarily occur when bleach is rinsed out too early. A slight brassiness is normal prior to the use of a toner, but a strong orange color means the bleach didn’t process enough. While it might scare you a bit to see that color on your locks, if it hasn’t been beyond 30 minutes, leave it go—you’re still in the safe zone.

How can I best prepare my hair for bleaching?

When you’re considering bleaching your hair, there are things you can do to prepare your hair in order to keep it in the best condition possible. 

  1. Before you bleach your hair, if you’re getting it done professionally, get a color consultation with your colorist. This helps your colorist know exactly what state your hair is in prior to bleaching and sometimes they can offer you some tips to use before and after so that you’re prepared ahead of time.
  2. Because bleach is harsh on your hair, it’s a good idea to start prepping your hair with as much moisture as possible before it is bleached. Shampoo in the weeks leading up with a gentle, moisturizing shampoo. Using conditioner and hair masks beforehand can also help prep your hair.
  3. Avoid shampooing your hair for a few days prior to bleaching. The natural oils in your hair will not disrupt the bleaching process and will actually help to protect your scalp in the process, particularly if your scalp is susceptible to irritation from chemical coloring and bleach.
  4. About 1 week before bleaching, avoid using heating tools on your hair. Heating tools dry out your strands and can make your hair more susceptible to breakage when it is bleached.
  5. After your hair is bleached, use products that will protect your color while maintaining the integrity of your hair. Sulfate-free products, moisturizing conditioners, hair masks, hair oils, and thermal sprays will help your hair stay as healthy as possible.

Does your hair become brighter the longer you leave bleach in?

Your desired color outcome is an important factor to consider when bleaching your hair. Simply put, the longer you leave the bleach on, the more your natural hair color will lighten. Of course, there are other factors to consider, though. If your hair was previously bleached or colored, you may want to be extra cautious with this, because there is a fine line between being lighter and damaging your hair to the point of no return.

How do you know when it’s time to remove bleach from your hair?

Throughout the process, you or your stylist should set timers to continuously check in on your color status and to decide how much longer it needs to remain on your hair. Timing will vary for everyone depending on hair type, prior color, and desired outcome. 

A good way to better determine how long you should leave the bleach on your hair would be to do a test strand prior to bleaching all of it. This will help you figure out just how long the bleach takes to get you to your desired color outcome without going too far and damaging your hair.

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