Can You Mix Semi-Permanent Hair Dye With Permanent Hair Dye?

close-up of a woman's hands using semi-permanent dye on her hair at home

Whether you want to avoid using ammonia and peroxide on your hair, or simply because you’re curious, if you’ve ever wondered, “Can you mix semi-permanent hair dye with permanent hair dye? You aren’t alone. Hair dyeing on the surface may seem like such a cut and dry procedure.

Yet, it’s not as simple as one would think. Each type of hair dye—semi-permanent, demi-permanent and permanent all have different chemical make ups. While it won’t cause serious injury or harm, I will explain in this article why mixing semi-permanent dye and permanent dye is less than ideal. 

Can I Mix Permanent Dye With Semi-Permanent Dye?

The biggest difference between permanent dye and semi-permanent dye is that semi-permanent does not contain ammonia or peroxide, whereas permanent does. Semi-permanent dye is ready to go, right out of the box. This type of dye is non-oxidative, meaning it doesn’t need to be combined with hydrogen peroxide to work. 

On the other hand, permanent dye requires a process of mixing with peroxide—in a non-metallic bowl, with precise measurements to work. Due to their chemical differences, it is nearly impossible for the dyes to mix evenly, (think of oil and water).

Semi-permanent dye was created to be less harsh on the hair and does not fully enter the hair cortex. To put it simply, it coats the hair with color, rather than invading the actual strands. As I stated before, permanent dye contains ammonia.

Ammonia opens up each strand of hair in order to deposit color onto the shaft. This creates a permanent change in the hair strand. Each type of dye was made for a specific reason, mixing them could produce extremely uneven hair color after only a few washes. 

Can I Mix Two Hair Colors Together?

The answer to this question is not black and white (color pun), get it? In fact, depending on what resource you look at there may be some that say absolutely not and then others that say, yes—and buy our specially formulated product to do so!

Well, I’m not trying to sell you anything. I’m just here to give information. You can mix two hair colors together, however, you need to make sure you know what you’re doing first. In order to get that perfectly desired shade you’re dreaming of, you need to remember the basic color rules.

This means mixing cool and cool colors, or warm and warm colors only. Never mix cool and warm colors together as they will counteract one another. The only exception to this rule is mixing with a neutral color.

Use a natural shade as your base and then mix either a cool OR warm color to move the shade whichever direction you desire. In addition, if you are a beginner or have never mixed two different shades before, it is suggested to stay within 3 shades of your base color until you have more experience. 

Can I Mix Demi-Permanent Hair Dye With Developer?

As a quick recap, demi-permanent hair color is slightly different from its sister hair dyes. This type of hair dye is in between semi and permanent. It shares the same qualities of permanent dye in that it is not ready for use straight from the box and needs to be mixed with a (weak) hydrogen peroxide mix in order to develop. 

On the other hand, it shares similar features of semi-permanent dye in that it mainly just coats the outside of the hair. It is not meant to completely change the color structure of the hair but rather to change the tone, enhance natural colors or cover greys. 

Demi-permanent dye doesn’t need a high level of developer to work though. It is fully capable of working successfully with just a low level of peroxide. Demi-permanent hair colors are stated to last anywhere from 6-12 washes before starting to fade. 

How Many Washes Does Semi-Permanent Dye Last?

Semi-permanent hair colors are beneficial for a few reasons. Their lack of ammonia/peroxide damage and their easy use with no mixing of chemicals involved are just two reasons. However, lasting vibrant color is not one of them. 

Semi-permanent hair dyes last anywhere from 6-8 weeks and this is if you wash your hair sparingly and avoid excessive sun exposure. Swimming pools also can cause semi-permanent dye to wash out quickly. It’s safe to bet that summer isn’t the ideal time to use a semi-permanent dye. 

In addition to environmental factors, how porous your hair is can also affect how long a semi-permanent hair dye will last in your hair before fading. Hair that is particularly porous (after bleaching for example) will hold color longer than hair that is not. 

Is Semi-Permanent Hair Dye Damaging?

When putting any chemicals in your hair, there is always a risk of damage. The ingredients in most hair dyes, bleach or in chemical straightening procedures break the bonds of your hair that bind protein strands together. This in turn causes hair to become more porous, literally leaving small holes in the cortex causing dry or coarse hair. 

However, since semi-permanent hair dye only coats the surface of the hair rather than penetrating the hair shaft itself, there is far less damage that is caused than with permanent dye. In fact, instead of causing hair to look damaged, semi-permanent hair dye can bring that vibrant, vivid shine and color back to dull locks. 

Final Thoughts: Can You Mix Semi-Permanent Hair Dye With Permanent Hair Dye?

Dyeing your hair well requires thought and knowledge in order to successfully achieve the look you want. Each type of hair dye is created for a specific purpose, so mixing two different kinds together is never a good idea.

While you can mix them, you aren’t going to get the results you want. Semi-permanent hair dye is meant to fade gradually with each shower over time, whereas permanent dye is meant to grow out naturally as your hair grows.

This imbalance of techniques will cause your hair to slowly start to look quite different than the results envisioned in your head. Attempting to cut corners by mixing two separate dye types can easily result in a hair catastrophe. So if you value the health of your hair, don’t do it. 

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By Cierra Tolentino

Cierra Tolentino is a beauty writer at Kintegra Research. She loves keeping people up-to-date with the latest beauty trends in skincare, hair care, and makeup. Finding answers to tough questions is her thing. When she has free time you can find her chasing down a clumsy toddler and obsessively drinking tea.