The skin barrier

Be prepared to have a healthy dose of biology to improve your knowledge. The current fashion in kbeauty is to strengthen the skin barrier with the help of ceramides and Centella Asiatica. Having a healthy skin barrier is an absolute requirement. 

The integrity of the skin barrier is depended on many factors among it the pH. Unfortunately, the pH is easily disturbed by skincare. In some cases, it is for the greater good and sometimes for the greater worst. 

I am a massive advocate of educating yourself to become more aware and be a conscious consumer when you choose your skincare. I hope this article will help you.  

The pH: 

pH stands for potential of Hydrogen, according to the Wikipedia page a Danish chemist introduced the notion of the potential of Hydrogen in 1909 (wikipedia).  

The pH value is the results of a calculus translating the activity of the hydrogen ion (H+) in a solution.

The skin barrier pH

The pH is a scale (1 to 14) measuring how acid and how basic a solution is. In skin care and living organism, the solution is water you know Miss H2O. Pure water has a neutral PH of 7, PH lower than 7 is acid and a PH greater than 7 is basic.  

The skin barrier pH scale

In real life, acid tastes sour and make your eyes water like when you bite into a slice of lemon juice (citric acid) or have a sip of vinegar (acetic acid) which I don’t recommend.

Our body has a different PH. 

Our body is a fantastic cellular engine tightly controlling the pH of every organs and fluid: blood as a PH of 7,3, gastric acid (your stomach) between 1,3 to 3,5, ileum (the gut after the stomach) 8… The concentration of Hydrogen ion ( so the pH) is necessary for many processes, the digestion, the production of energy (= cellular respiration, see my review on the Missha Time revolution night repair), the fight against bacteria and many others.  

To put it simply the chemistry of life is dependent on the concentration of hydrogen and our skin also. 

The skin barrier: the stratum corneum

I am pretty sure you have heard of the skin barrier especially with the hype on Centella Asiatica based products. The skin barrier is the first fence of defense of our body. It protects our inner cells from dehydration (you know the famous transepidermal water loss) and also from hyperhydration (when you go to the beach the water do not enter your body). It also protects us from viruses, bacterias, dust, particles from pollution… 

How does the skin barrier protect us? 

What protects us is a thin layer of dead cells (corneocyte) embedded into a complex substance often refer as sebum or acid mantle. 5 to 15 sheets of dead skin cells make the stratum corneum.

Skin barrier stratum corneum

Those cells are similar to roof tiles that are stacked on top of each other embedded into cement. The acid mantle fills the space between the dead cells and is made of a variety of lipids and natural moisturizing factors.

Skin Barrier acid mantle

What is the pH of the skin barrier? 

You probably already know the answer, the pH of the skin barrier is acid, but like everything in life, things are always more complicated. Indeed, the PH of skin barrier varies from acidic to almost neutral in the deeper layers of the skin barrier. Funny enough, the researchers have also seen the same gradient in mice! Who would have thought mice have an acidic skin barrier.   

Skin Barrier ph gradient

The integrity of the skin barrier depends on the pH: 

The integrity and the function of the skin barrier is dependant on the pH. Increasing the pH of the skin barrier leads to many problems:

  • Slowing down of the skin barrier recovery 
  • Disruption of the structure of the lipids
  • Increasing transepidermal water loss = dryness
  • Increasing the permeability of the skin barrier 
  • Proliferation of bad bacteria 

Skin diseases are associated with higher pH value: 

Close to neutral pH is detected in the impaired skin barrier of patients with Eczema, Ichthyosis vulgaris « dry patches » and diabetic patients. 

My conclusions:

My final point is that the skin needs 3 to 4 days to recover from a neutral pH exposure. Neutral pH is pure water imagine what you do when you use soap that has a pH of 8 to 9!

Overall, the increase of pH leads to many biological dysfunctions of the skin barrier. Even though, you do not see the disruption does not mean that you are not impairing the delicate health of your skin barrier. On the long run, it adds to the aging process. 

If you want to know more, watch my youtube video and the one from the charming Ben Neiley and subscribe to him. If you are concerned with the pH of your skincare products, read my blog post on double cleansing.


I hope you have found this article interesting and you are now convinced of the terrible impact of using neutral to basic skincare products. 

A bientôt, 


PS: Stop using soap ! 😉

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