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In hair color, ammonia is very efficient at swelling hair shaft and opening the cuticle, which allows hair color to penetrate more efficiently into the hair’s cortex.

Why is MEA not as efficient as ammonia?

The MEA molecule has a molecular weight of 61, while the molecular weight of ammonia is 17. Therefore, MEA is 3.5 times larger than ammonia. When permanent hair color and peroxide meet, ammonia acts as a catalyst to start the oxidation reaction. This reaction lightens natural pigment in the cortex and allows artificial color to deposit INSIDE the cortex.

How do various shades of MEA-based permanent hair color perform? For example: brown, blonde, red, and for gray coverage of those shades?

Because of its large-sized molecule, MEA-based permanent hair color products don’t lighten efficiently enough to produce exceptional light blondes and vibrant reds. This can have higher irritation potential. Also, browns, reds, and other shades don’t cover gray well or may not last as long.

How does MEA perform in demi-permanent hair color?

The use of MEA is fully justified in demi-permanent color because the lightening of natural pigment isn’t necessary. This type of hair color product is designed to leave no line of demarcation and gradually fade from the hair.

Is MEA bad for the hair?

MEA is not fundamentally bad for the hair. The amount of MEA used in a particular hair color is what creates potentially negative results. The amount of MEA in hair color varies from shade to shade. With MEA, it is not uncommon to have 6% in darker shades and 10% or more in the lightest blonde shades. For ammonia, the amounts range from 1.5% in the dark

shades and up to 3.5% in the high lift shades.

What IS MEA?

MEA, mono-ethanolamine (C2H7NO), is an odorless, alkaline reactive liquid chemical compound that is produced from the reaction of ethylene oxide with ammonia.


Ammonia (NH3) is an alkaline compound of hydrogen and nitrogen that is both naturally occurring and man-made. It is water-soluble, exists in both gas and liquid form, and has a strong odor.

How does MEA function in hair color?

In hair color, MEA accomplishes the first step, which is to open the hair’s cuticle by swelling the hair. However, it is not as efficient as ammonia at penetrating the cortex.


Ammonia in hair color is not fundamentally bad for the hair. When both ammonia (catalyst) and peroxide (oxidation) are used with hair color, tiny molecules carry dye all the way into the cortex where they react to remove natural pigment and expand artificial pigment to a size that cannot be washed out, thus creating a permanent color.

What is the result of a high amount of MEA in hair color products?

MEA is not volatile and can remain in the hair even after the hair color has been removed. In the 24 hours following the color service, the residual MEA can cause progressive darkening and dull the shade. Some color companies that use MEA in permanent hair color counteract this by using a specially formulated shampoo that contains ammonium

hydroxide, the liquid form of ammonia, to remove residual MEA.

Why doesn’t MEA-based hair color have a strong odor compared to ammonia-based hair color?

Compared to ammonia, MEA is not as strong of an alkali catalyst. While an MEA residue remains in the hair, ammonia’s odor is noticeable as it “escapes” from the hair.

Why do some hair color companies prefer MEA over ammonia?

The lack of odor.

Why do some hair color companies prefer ammonia over MEA?

The color results of ammonia-based permanent hair color remain more predictable than MEA-based Hair color, providing more longevity, vibrancy, and superior gray coverage.

Mags Kavanaugh


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