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How Long To Leave Hair Dye In: A Matter of Time

by Sherri Owens

Leave hair dye in for about 30 to 45 minutes or as recommended by the manufacturer.

I have been a colorist for quite a long time. When pushed for time, I have resorted to using box dyes as well. This is why I know exactly how long to leave hair dye in when using store-bought brands.

Here is your guide to how long to leave the dye in and everything else you need to know to keep your locks looking good.

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How Long Do I Leave Hair Dye in My Hair?

So, let's get to the most important question:

How long should hair dye stay in before washing?

On average, you will need to leave hair dye in for 30 to 45 minutes before washing your hair out.

The exact time that you should leave hair dye in can depend on whether you are using a permanent hair dye or a semi-permanent dye.

As you can tell from the name, permanent dye is meant to last a lot longer. Therefore, the processing time will be longer as well, as the hair dye needs more time to settle in.

When it comes to semi-permanent hair dye, though, the dyeing process isn't quite as long.

To be absolutely certain, always read the instructions on the box.

Applying Hair Dye onto Brown Hair

What Happens If You Leave Hair Dye In Too Long?

It is only natural to wonder about this.

Most people are curious about this question because leaving hair dye in your hair for longer than recommended could result in a darker shade.

So, does leaving dye in longer make it darker?

Yes, when you leave hair dye in your hair for longer, you can end up with a darker shade than what is desired.

While this may sound like a good thing, it isn't necessarily the case.

For one thing, if you leave in permanent hair dye or semi-permanent hair dye in for longer, there is no guarantee of what your dyed hair will turn out to look like.

Sure, your hair color may be darker, but it may also result in an unpleasant hair color, far from the result you were hoping for.

In short, you will have no control over the shade your hair will be.

Then, there is also the possibility of damage.

Woman's Hair is Dyed and Ready to Remove

Can Leaving Hair Dye in for Longer Cause Damage?

Even if you aren't worried about the final dyed hair color, you should be concerned about hair damage.

This is especially likely when you leave permanent hair dye on for too long, but it's just as possible with semi-permanent dyes.

What a lot of people don't realize is that hair dye is made up of rather harsh chemicals.

The chemicals work by lifting the protective proteins on your hair strands. In doing so, the color can penetrate the hair and can change the chemical composition of the strands, resulting in a color change.

Leave these on your hair strands for too long and they will penetrate further into the hair shaft, right into the hair cuticle.

This can compromise and damage your hair, causing dry and brittle hair, split ends, and breakage.

To avoid risk damaging your hair, make sure to pay attention to the instructions provided with permanent and semi-permanent hair dyes.

Hairdresser Applying Hair Protector

What You Should Know About the Right Way to Dye Your Hair

Want to make sure you get the process just right? Here are the things to keep in mind:

Use the Right Box Dyes

Dyeing your hair can be a pricey procedure, even when done at home. Despite this, it is important to buy a good-quality hair dye.

It is the only way to guarantee a nice, long-lasting hair color. Stick to brands like L'Oréal Paris, Garnier, John Frieda, Clairol, etc.

Hair Dye in Bowls

Consider Your Existing Hair Color

Are you trying to dye your natural hair? Or, do you have previously colored hair?

The processing time can differ for each type. For instance, if you have virgin hair, then it may take less time for the color to settle in.

Therefore, you may not have to leave the hair color in for more than 30 minutes.

However, if you have color treated hair, the process can take longer.

This doesn't mean that you should leave hair dye in for longer, though. At most, it should be kept in for 45 minutes unless recommended otherwise by the manufacturer.

It simply means that you may require more than one application of hair color to get the desired result.

If you are dyeing gray hair, the chemical process can often take more time. This is especially true if you are covering gray roots.

Due to this, you will likely need to keep the permanent or semi permanent hair color in your gray hair for up to 45 minutes.

To fully cover gray hair or white hair, you may need to dye your hair more than once.

It is a good idea to visit a hair colorist when dealing with gray hair.

Woman Choosing a Suitable Hair color

Be Mindful of Your Hair Thickness

Always consider the thickness - or fineness - of your hair as this can play a role in the duration of leaving in the dye.

When dyeing fine hair, you should leave it for the least recommended time - around 30 minutes.

This is because the shaft is quite thin and it doesn't take as long for the dye to penetrate the strand and settle in.

Leave the dye in for too long in thin hair and you could end up damaging it quite a bit.

With medium hair and thick hair, the process takes a bit longer. This is especially true for thick hair.

This means that you will have to leave the dye in your hair for up to 45 minutes.

Make sure to not leave it in any longer than this is as you could damage even thick strands if you do.

Hair Dresser Checking Hair Density

Think About Hair Porosity

Hair porosity is all about how porous the hair is or how easily and quickly the dye will be absorbed into the hair shaft.

High porosity hair will absorb moisture and dye more quickly, while low porosity hair will not.

To test the porosity of your hair, fill a bowl with water. Then, take a strand and place it on the surface of the water.

If the hair floats after a few minutes, it has low porosity. As a result, you may need to leave in the hair dye for up to 45 minutes at a time.

If the hair sinks, it has high porosity. Therefore, you can leave the dye in for up to 30 minutes.

Hairdresser Helps a Woman Pick a Hair Color

A Guide to Dyeing Your Hair the Right Way

If you are intent on dyeing your own hair, here is how to make sure everything goes according to plan:

Lift Any Existing Hair Color

If you're rocking your natural pigment, there isn't much prep work to do. However, if you have hair that is already dyed, you can't just add the new color on top.

First, you need to remove the dyed pigment.

To do this, you can use either a color stripper or clarifying shampoo. A color remover should get the job done in one day.

You may need to use the shampoo a few times to completely get rid of the color.

Keep in mind that these process can be rather taxing on the hair. Therefore, you will need to follow it up with some deep conditioning treatments to restore the health and luster.

Washing Hair at the Saloon

Deep Condition Your Hair Before Coloring

It doesn't matter what condition your hair is in; make sure to deep condition it before you dye it.

Do this about three or four days prior to dyeing your hair. This way, your hair will be nice and healthy and less likely to suffer damage as a result of the dyeing process.

If you have especially brittle or dry hair, start conditioning it several weeks before dyeing it. This will result in a more polished finished result.

Hairdresser Prepping Customer's Hair

Choose the Dye Color Wisely

The first thing to keep in mind is to avoid looking at the model on the box. This won't give you a realistic result.

Instead, look at the swatches provided on the top or side of the box. This will give you a better idea of what your hair will look like once it is dyed.

If you are using a semi-permanent dye, look for a somewhat lighter color, as this type darkens the longer it's left on your hair.

With permanent hair dye, look for a shade that's darker than what you want the end result to be.

Hair Stylist Holding Hair Dye Palette

Color Your Hair When Dry

Keep your hair dry before coloring it. Wet hair will lead to an uneven color.

If you want, you can work on hair that hasn't been washed for a day or two.

Colourist putting hair dye on a lock of hair with foil

Use a Brush

A lot of dyes may come with an applicator bottle but don't use it, as you can guarantee that you will dye all your hair evenly.

Instead, pour the dye into a bowl. Then, section off your hair and use a brush to paint the dye on.

Hair Dyeing Process with a Brush

Wash and Condition Properly

Once you leave the dye in for the recommended amount of time, wash it out with cold water.

Then, make sure to condition the hair properly. Not only will this set the dye but it will also ensure that your hair looks healthier.

Hairdresser Washing Customer's Hair

This is what you need to know about how long to leave in hair dye. I have also included lots of great tips and tricks to ensure that you can dye your hair at home and enjoy the result. Good luck!

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