Why the evolution of hair colour chemistry may be less about power and more about precision.
Well, It’s Been a While…
Back in 2019, I wrote about the science behind oxidative hair colour, particularly the role of ammonia and monoethanolamine (MEA).
Remember the debate? Ammonia versus ammonia-free. Which was better? Which was gentler? And which was doing more damage? Well, a few years and quite a lot of learning later, I think there’s a more interesting conversation to be had.
Working within the professional hair industry, across different brands and technologies, has given me the opportunity to explore how hair colour formulations continue to evolve. And one thing I’ve come to appreciate is that perhaps we’ve been asking the wrong question.
What if the evolution of alkalizing technology isn’t simply about finding something stronger, but about finding something more precise?
Let me explain.
A Little Chemistry Refresher
We know that alkalizers play an essential role in oxidative hair colour.
They help create the alkaline environment needed for colour chemistry to work, influencing hair swelling, dye penetration and the oxidation reactions involved in colour development and, where required, melanin lightening.
But the alkalizer isn’t doing all this work by itself. Hydrogen peroxide plays a central role in the oxidation of natural melanin and the development of oxidative dye molecules. The alkalizer helps create the conditions for these reactions to happen effectively.
And that’s where things get interesting. Because creating an alkaline environment is one thing.
Controlling that environment is another.
Ammonia: Still a Very Useful Ingredient
Ah, ammonia. The ingredient we seem to love to hate!
Despite its reputation, ammonia remains an extremely effective alkalizing agent in permanent hair colour. It’s efficient, well understood, and its volatility gives it some useful characteristics in formulation. MEA, on the other hand, is much less volatile, which helped make it a popular alternative in ammonia-free colour systems. But as we’ve explored previously, ammonia-free doesn’t necessarily mean less damaging.
Interestingly, research comparing certain MEA-based and ammonia-based formulations has shown greater fibre damage with the MEA systems under the conditions tested.¹
Does that mean ammonia is always better? Of course not. It means we need to stop judging an entire formulation by the presence or absence of one ingredient. And perhaps that’s where our thinking needs to evolve.
It’s Not an On/Off Switch. It’s a Volume Control.
Think about the volume control on your music system. Sometimes you want the music turned up. Sometimes you want it playing quietly in the background. You don’t automatically turn everything up to maximum just because you can. Hair colour chemistry is a little like that.
A demi-permanent colour designed primarily for tonal deposit doesn’t necessarily need the same alkaline conditions as a permanent colour designed to achieve significant lift.
So why would we approach their alkalizing systems in exactly the same way? This is where the idea of modulating alkalinity becomes interesting. By selecting and combining different alkalizing ingredients, formulators can fine-tune the chemical environment to suit the intended colour performance. It’s not simply about making the formulation stronger or weaker. It’s about creating enough alkalinity to do the job, while avoiding unnecessary chemical stress on the hair.
And importantly, it’s not just about the starting pH. It’s about how that alkaline environment behaves throughout the colour process.
Arginine: More Than Just an Amino Acid?
One interesting development is the use of arginine-based alkalizing technology. Arginine is an amino acid naturally found in hair proteins, but it also has chemical properties that allow it to contribute to alkalinity in cosmetic formulations. In some demi-permanent oxidative colour systems, arginine-based technology can be used without any other alkalizer.
In permanent colour, it can also be combined with low levels of ammonia as part of an alkalizing system designed for the greater demands of permanent colour chemistry. And this is what I find interesting. Rather than simply replacing one alkalizer with another, we’re seeing different ingredients used in different combinations depending on what the formulation needs to achieve. Research into arginine in oxidative colour isn’t entirely new, either.
A study published in 2004 investigated the partial replacement of ammonia with arginine and reported reduced changes in certain measures of hair surface properties and wet tensile strength.²
Interesting? Absolutely.
Proof that every arginine-based colour is less damaging? No. And just because arginine is an amino acid naturally present in hair doesn’t automatically mean that every formulation containing it is gentler.
As always, the complete formulation matters.
Trisodium Phosphate: Another Tool in the Box
Another ingredient worth mentioning is trisodium phosphate, or TSP. An alkaline salt, TSP can contribute to the alkalinity of a formulation and can form part of a broader alkalizing system. Its chemical behaviour differs from that of ammonia and MEA, offering formulators another ingredient to consider when designing the overall alkaline environment.
And that’s really the point.
It’s not necessarily about finding a better alkalizer. It’s about having different tools available to achieve the desired result.
More options, and opportunities for greater refinement.
Of course, whether a particular combination improves colour performance or hair condition still needs to be demonstrated through testing.
But Here’s Something We Often Overlook….
We talk a lot about pH in hairdressing. And rightly so. But two formulations with the same pH don’t necessarily behave in the same way.
Why?
Because pH is only part of the picture. We also need to consider things like buffering capacity and alkaline reserve.
Without turning this into a chemistry lecture, buffering capacity tells us how strongly a formulation resists changes in pH, while alkaline reserve gives us information about how much acid is needed to neutralise its alkalinity to a defined endpoint.
These are different measurements, and both can tell us something that pH alone cannot. Think back to our volume control. It’s not just about setting the volume when the music starts. It’s about how the system behaves throughout the performance.
And this is why simply comparing pH numbers, or deciding that one ingredient is gentler than another, doesn’t always tell us very much.
So, Are Evolving Alkalizing Technologies Better?
Well, that depends on what we mean by better. Better lift? Better deposit? Better grey coverage? Better hair condition?
These are different questions. And they may require different formulation approaches.
I think one of the most interesting developments in modern hair colour chemistry is the opportunity to be more selective about how we create and manage alkalinity.
But let’s not confuse innovation with proof.
A new ingredient, or a different combination of ingredients, isn’t automatically an improvement. We still need good evidence, meaningful comparisons and, ultimately, products that deliver the results they promise.
The Hairy Truth?
Ammonia isn’t necessarily the villain.
MEA isn’t automatically the hero.
And evolving alkalizing technologies aren’t magic ingredients.
But what they offer is the possibility of a more refined approach to colour formulation.
Rather than simply asking how much alkalinity we can create, perhaps we should be asking how much we actually need, and how best to manage it.
Because more isn’t always better. And less isn’t automatically safer.
It’s about having enough of the right chemistry, in the right environment, to achieve the right result.
Or, to put it another way…
Maybe it’s time we learned to control the volume.
Until next time,
Learned & Still Learning.
Hairy Truths
References & Further Reading
1. Bailey, A. D., Zhang, G., & Murphy, B. P. (2014). Comparison of damage to human hair fibers caused by monoethanolamine- and ammonia-based hair colorants. Journal of Cosmetic Science, 65(1), 1–9. https://pubmed.ncbi.nlm.nih.gov/24602818
2. Oshimura, E., & Ino, M. (2004). Effects of arginine on hair damage via oxidative coloring process. Journal of Cosmetic Science, 55(Supplement), S155–S170. https://pubmed.ncbi.nlm.nih.gov/15645092
3. Ali, N., Marsh, J., Godfrey, S., & Williams, D. R. (2018). Aqueous MEA and ammonia sorption-induced damage in keratin fibers. ACS Omega, 3(10), 14173–14180. https://doi.org/10.1021/acsomega.8b01189
These studies examine specific formulations or experimental conditions. Their findings should not be interpreted as demonstrating that one alkalizing ingredient is universally superior to another.
Previously on Hairy Truths: Oxidising Colours; The Science (2019)
