How Long To Leave Hair Dye In? The Hair Professionals’ Answer

In terms of hair dye and hair care, timing is the critical factor in determining the effectiveness of your dying. Proper timing brings you a dynamic hair color regardless of ambient effects like water or heat exposure. 

Even though many people prefer hair dye to their natural hair too often, they don’t know how long to leave hair dye in for vibrant colored hair.

Ivirgo Hair Factory will answer these questions in this article and provide some helpful information. Now, let’s jump straight into the article!

How Long To Leave Hair Dye In
How Long To Leave Hair Dye In

How Long Do You Leave Hair Dye In? 

In most cases, hair dyes require 30 to 40 minutes to penetrate your cuticle layers and change your natural hair color. Therefore, you should leave the hair dye in for at least 30 minutes before finishing the dyeing process.

However, the duration is not true for every hair shaft type. Some people must wait for 10 to 20 minutes more because they have thicker hair than others. Chemical penetration is slower as hair thickness increases.

Hair dye products typically come with detailed instructions about how to apply the color to your natural hair or how long you should leave the color hair in. Manufacturers have conducted many tests to provide detailed explanations.

Several other factors determine the duration of leaving your hair dye:

Hair Color

The analogy between your natural hair color and the hair dye is critical. For example, if your hair is naturally black, dark colors can blend in your hair shaft more quickly. Therefore, this process can be faster than usual.

According to this factor, you can decide how long you should leave hair dyed in because every hair dye product comes with some images showing the result.

You need to compare the desired color with your natural hair color to make a wise decision on choosing the color for your hair. 

How Long To Leave Hair Dye In
Consider carefully the color you are going to apply

Hair Thickness

Human hair is classified into three thicknesses: thin, medium, and thick. Customers should know their hair thickness to have proper timing. 

For those with thin strands, consider leaving the dying job for at least half an hour. It allows chemicals to enter the natural hair shaft within effectively, which can retain the color as long as possible. 

Medium hair thickness possesses dense cuticle layers and heavier follicles. It may take 30 to 40 minutes for color pigments to open hair cuticle layers and change your natural hair color.

Thick hair strands require extra chemicals to achieve the best dying result. Hair stylists must apply color in small sections to ensure your natural hair gets enough substances. 

Many hair salons consider people with thick hair strands “time-consuming” cases, which takes at least several hours for a desired dying job. You should set your schedule correctly to avoid unexpected things during the dying process.

Hair Porosity

Hair porosity typically refers to the moisture sorption of your strands in particular situations. You can easily explore your hair porosity by throwing a few strands in water and seeing their changes. 

If the strands sink in less than four minutes, your hair has a high porosity rate. In contrast, strands can float on the water surfaces for five to ten minutes and deliver a low porosity rate. 

Hair strands with low porosity rates can resist dyeing jobs stubbornly and take a longer time for hair dyes to change the previous color of your hair. 

Regardless of how porous your hair is, it would be best to wait at least 45 minutes to see the desired results.

How Long To Leave Hair Dye In
Try sinking your hair strands to test the hair porosity rate

What Happens If You Leave Hair Dye In Too Long?

Leaving hair dye in too soon might affect the drying process, which is not enough time for color pigments to penetrate your hair shaft. So, what will happen if you leave hair dye for too long?

Semi-Permanent Dye

With semi-permanent dye, hair stylists will apply chemicals at a moderate concentration. These chemicals don’t have harsh ingredients, so you don’t have to worry about their penetration.

Forgetting to rinse the colored hair on time is not a significant mistake, but staying too long with semi-permanent dye on your natural hair could result in an unanticipated dyeing job.

Permanent Dye

The permanent dye comes with harsh ingredients such as oxidizer,  hydrogen peroxide, and paraphenylenediamine. These chemicals can immediately open your cuticle layers and change your hair within several minutes. 

Remember to rinse your natural hair on time after the dyeing process. If hair strands absorb too many chemical substances, your hair will be dry and lead to hair damage over time.

How Long To Leave Hair Dye In
Remember to rise after dying job

What Should You Do If You Leave Your Hair Dye Too Long?

You can consider the solutions below to handle excessive hair dye according to hair experts’ suggestions. 

  • Apply conditioners to provide humidity to the damaged strands instantly.
  • Consider adjusting the hair washing schedule to protect hair from shedding
  • Avoid hairstyling tools such as hair brushes, hair dryers, and hair rollers until the hair strands recover.
  • Consult hair stylists to find the best solution for your case.


Can You Leave Hair Dye In Overnight?

The short answer is no. The average time for color pigments to change your natural hair color ranges from 30 to 40 minutes. Leaving hair dyed longer won’t help you have a vibrant color.

Instead, you might encounter hair loss and dry strands, as the chemicals absorb oil on your hair and make it dry very quickly.

Should I Shampoo After Hair Dye?

Hair dyes need a certain amount of time to enter your hair shaft. After your dying job, consider waiting for at least two days before washing your hair. Some people wait for four days to achieve better results. 

Should You Comb Through Hair Dye?

Absolutely! You should use a wide-tooth comb to distribute the color uniformly over each section of hair. After you’ve colored one section of the hair, comb the remainder using a wide-tooth comb. 


Many people dream of having a dynamic hair color in the long term. The article has provided a straightforward answer: How long to leave hair dye in?

I hope you can handle your problem and show off your healthy-colored hair at home or outside. Thank you for reading!

Hair Care Expert at Ivirgo Hair | + posts

I am Thomas Taw, the CEO of CITIZENSNIPS. I have experience in hair product development and chemical research, as well as sustainable resource engineering. In 2009, I co-created Sunsilk, one of the world's leading haircare brands. More recently, I was the CEO of SMOKINGPANDA LTD. I am a professional with a strong track record in delivering tangible results.

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