One of my favourite subjects at the Make Your Own Skincare Workshops is the topic of pH. Unless I have a chemical engineer in the room (happened once so far!), most people shake their heads when asked if they know what pH is and why it’s important in making skincare products. So here is a quick and – hopefully – easy to absorb guide to pH in skincare and haircare products.

1. What is pH?

Quite unscientifically, there is no single opinion on what exactly the term pH stands for! The Danish chemist Sorensen, who first introduced the concept in 1909, did not think too much about documenting why he named the new measurement that way. As pH refers to concentration of hydrogen (the simplest chemical element on Earth) in water-based solutions, “H” stands for Hydrogen. “p”, however, can either mean “potential” or “power of” – choose which one you like.

To be able to compare pH of various water-based liquids, a pH scale between 0 and 14 is used: 0 = being very acidic and 14 = very alkaline or “basic”. In the middle of the scale is number 7, which is neutral (neither acidic nor alkaline). And this is the pH of water – and our blood is very close to it and has a pH of 7.4. 

An easy way to remember which end is which is to think of lemons and baking soda. Lemons are usually just a few and they are acidic – their pH is 2. Baking soda is hard to count, as it’s a lot of it -> Think of it to be in the higher pH range (it’s actually 9.5).

You might think that the difference between 2 and 9.5 is not a huge one – but guess what? The pH scale is logarithmic, not linear. This means that each full number is a ten-fold increase.

Example: Between 2 and 4, the difference is 10×10 times = 100 times! And while 100 times difference is not really a huge deal in pH terms, greater differences can cause near-volcanic reactions: think what happens when you mix baking soda (pH = 9.5) and vinegar (pH = 2).

2. But what is the pH of our healthy skin and hair?

The uppermost skin layers are slightly acidic, with a pH of around 4.7 to 5.0. Men’s skin is usually more acidic and more mature skin is less acidic, but overall the values stay in the acidic range. 

When a baby is born, their skin has a neutral pH that within a few weeks develops its acid mantle. That acid mantle plays an important role in our body’s ecosystem and acts as a protective shield from harmful external microorganisms.

Our hair’s natural pH is also somewhat acidic, around 4.5 to 5.5. However, shampooing, colouring and bleaching push the pH into the alkaline zone – which makes sense if we remember that any soap-like substances and bleach are in the higher pH range (see the table above). 

3. So, what does it all mean for my skin and hair products?

Occasional contact with substances that have a pH outside of the natural skin and hair pH of 4.7-5.5 is unlikely to cause much harm.

However, frequent exposure to too acidic (think, acidic peeling every day) or too alkaline (for example, frequent hair bleaching) may lead to a serious damage and even health issues. Skin sensitivities, redness, eczema and dandruff can all be related to over-use of products with a too high or too low pH.

So having a daily lemon peel with a sugar scrub is not such a great idea as some celebrities might suggest.

4. And finally – Do I need to worry about the pH of my water-based skincare and haircare products?

Thankfully, in most cases there is no need for concern. Most professionally made products for skin and hair are pH-balanced. Some even “boast” about that on their product labels. However, this claim is more of a marketing trick: ensuring the pH is within the natural zone comes with being a cosmetics formulator and manufacturer.

If, for some reason, you have doubts about the pH level of a certain product you are using, you can run a pH test at home.

You will need:

-> pH strips (you can buy them, for example, from here)

-> demineralised water (you can get from any car supply shop or even a petrol station)

-> product to be tested

-> a ceramic or glass container

What to do: First, mix 1 part of the tested product with 9 parts of the water (for example, if you have 1 gr of a facial cream, you will need to add 9 gr of water). Then dip about 5 cm of the pH strip into the solution. Compare the colour of the strip with the colour chart on the pH strip kit to find out the pH of your product. Done!

Or you can use a professional pH meter like the one in the top image that will show you a much more precise reading (the process of mixing water with the product will still be the same). 

Hope you enjoyed the article and feel now much more sure about this whole pH thing.

Aly XO