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Ammonia vs MEA (what's the difference)

Today, we're going to get a little science-y. I will keep this post short and to the point, but if you want a more in-depth explanation, head over to my podcast where I dive deep into the nuances and the pro's and con's of each.

We've all seen different color manufacturers produce color that is "ammonia free". The marketing and push behind this movement has been monumental..having hairdressers believing that one is better or worse than the other. See, you have to understand that when it comes to color matters. You have to, as a manufacturer, create a problem and then offer the solution to said problem. Sometimes, the problems aren't really problems. Sometimes, a new product gets launched and needs a good story. Follow my drift?

The "story" about Ammonia vs MEA goes a little something like this:

(Cue: The Problem)

Ammonia is a harsh chemical.

Ammonia can cause a severe chemical reaction.

Ammonia is bad for the hair.

Ammonia has a strong odor.

Ammonia is bad for your health.

(Cue: The Solution)

MEA, aka, monoethanolamine.

MEA is apparently a magic solution these days, with claims that it is organic, natural, less abrasive and so on.

Here's the thing, I love working with color that uses ammonia as the alkalizing agent.

I also love working with color that uses MEA as the alkalizing agent.

My issue is that most of us colorists don't really know the difference between the two and when to use what. We just buy in to the marketing.

Let me break this down, as simply as I can, in the best way that I understand it, so that maybe you can get some clarity and then make an informed choice on when you use what.

Both MEA and AMMONIA are alkalizing agents used in hair color. During the hair coloring process, an alkalizing agent is necessary to help swell the cuticle layers, so that the dyes can penetrate into the cortex of the hair. When a hair color is advertised as "ammonia free", the alkalizing agent is typically "MEA". Sometimes "AMP" aminomethylpropanol.


-Ammonia is a gas-based alkalizing chemical which means that it evaporates in a short amount of time.

-Ammonia is highly efficient in swelling the cuticle layers, because it provides the alkalinity needed to deliver the color molecules into the cortex.

-Fewer than 1% of people actually have and allergy or sensitivity to ammonia.

-Ammonia has a strong odor, however, that odor usually dissipates within a few minutes of mixing with peroxide.

-Molecular weight of Ammonia is 17.

-% of ammonia in hair color ranges from 1.5% in darker shades to 3.5% in ultra lifts.


-MEA is a liquid-based alkalizing chemical. Differingfrom Ammonia, which is a gas and can dissipate, MEA must be removed from the hair.

*Some manufacturers who produce MEA based hair color will often have a shampoo that is recommended to wash out the hair color. These shampoos almost ALWAYS contain ammonium hydroxide , liquid form of ammonia, to remove residual MEA)

*Residual MEA left in the hair can cause progressive darkening and dull the hair color.

-MEA can swell the cuticle layers, but is not as efficient in delivering the dye molecules into the cortex.

-MEA is odorless (please know that just because it does not smell, doesn't mean its still not a chemical)

*The fact that it is odorless is one of the main marketing points with MEA based permanent color, alluding to the fact that because there is no smell, its not "as bad" for the hair.

-Molecular weight of MEA is 61.

*Because of its larger size, MEA based permanent colors can not fracture melanin and lighten the hair efficiently enough to get bright and vibrant results or adequate gray coverage.

-% of MEA in hair color ranges from 6% in darker shades to 10% or more in lighter shades.

The biggest difference between Ammonia and MEA is the medium in which they exist (gas or liquid) and fumes.

Both are alkalizing agents.

Both are chemicals.

In my personal opinion, when it comes to permanent hair color, when I need some lifting action, I would choose a color that is Ammonia based. I feel that I get substantially better results. When it comes to a Demi-permanent color, I will often reach for an MEA based color because I don't want any lift, and a soft and subtle grow out.

As long as you know the main differences between the chemicals, you have the power to choose which to use, when and why. There is a time and a place for every hair color option. Don't buy into sales-driven fluff. Know your shit, and know it well.

Until next time,

Happy Hair Coloring


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