Are you aware of the pH value of the products you use? If you care about your skincare, you should care about the pH value of the products on your bathroom shelf.
To understand the importance of this topic, let’s go over what pH value is in the first place, how it is defined and what is your skin’s pH. This will be your guideline for selecting and layering products.
The acidity of a solution depends on the concentration of hydrogen ions (H+). It is expressed by the physical quantity pH, which is defined as the negative logarithm of the concentration of H+ ions.
At 25℃, the pH value can be between 0 and 14. Acidic solutions are those whose pH is less than 7, neutral solutions have a pH value of 7, while alkaline solutions are those whose pH is greater than 7.
In the 19th century, we have discovered that the surface of the skin is acidic. A century later, it was dubbed the "acid mantle". The pH of the skin surface varies between 4.5 and 5.5 and plays a crucial role in skin physiology. It is important for regulating keratinization and desquamation, wound healing, the action of the enzymes phospholipase and glucocerebrosidase, and the protection of the skin against the colonization of pathogenic bacteria.
The pH value of the skin is affected by substances excreted on its surfaces, such as sweat, sebum, and natural moisturizing factors (NMF). Likewise, sebaceous and eccrine glands secrete acids such as amino acids, free fatty acids, and lactic and butyric acids. Also, on the skin's surface, some bacteria produce lipases and esterases that break down triglycerides into free fatty acids, which leads to a decrease in pH, which then creates unfavorable conditions and leads to an increase in pathogenic bacteria.
Various external factors, such as soaps, detergents, and cosmetic products, can and do affect the pH of your skin. Using such products can cause a change in the pH of the skin, consequently negatively affecting the function of the epidermal barrier and the microbiome of the skin. Maintaining the physiological pH of the skin is of the utmost importance. Therefore it is necessary to pay attention to the pH value of the cosmetic products we use.
Face cleansers are a great example. Skin cleansing is a complex physicochemical interaction of skin, surfactants (PAT) and water. Stratum corneum is the main protective barrier of the skin, so paying special attention to choosing the right cleanser is a must. A proper cleanser must be gentle and well-selected. This ensures you’re doing a good job of removing dirt, sweat and sebum from the skin without damaging the stratum corneum.
When cleansing the skin, irritation can occur through the interaction of PAT and the structure of the stratum corneum, lipids, and proteins. This is where the pH of the product comes into play. Soap-based cleaning products are alkaline by nature. On the other hand, most cleansing products with synthetic PAT, so-called syndetics, are close to neutral pH or slightly acidic. Alkaline facial cleansing products have a significantly higher pH than our naturally acidic skin. Such a drastic increase in the pH of the skin significantly compromises the hydrolipidic barrier, which makes the skin less able to defend itself against the proliferation of microorganisms that can cause acne and infections. Using mild non-ionic and/or amphoteric PATs and conditioning ingredients in a skin-like pH medium reduces the irritant potential of skin wash products.
After removing surface impurities, the skin needs to compensate for the moisture lost during cleansing. Likewise, after cleansing the face, the pH of the skin is elevated and it needs to be brought back to an optimal pH of 5.5 to preserve the barrier function of the skin. Therefore, scientists recommend you use a moisturizing essence with a balanced pH.
The pH value plays a major role in every cosmetic product, but especially in pH-sensitive products such as chemical exfoliants. For AHA and BHA acids to be effective and for the difference to be visible on the skin, they should be in an acidic pH medium, ideally between 3 and 4.
An interesting example is vitamin C, a powerful antioxidant that prevents damage caused by UV rays. Products with ascorbic acid should be in a medium with a pH value of 3.5, which is necessary for optimizing the absorption of vitamin C. What this means for your skin is that you’re less likely to experience unwanted reactions such as irritation and redness. If your skin is leaning towards the sensitive side, vitamin C derivatives in a pH-neutral medium are a more suitable choice.
It should be noted that some cosmetic ingredients are not to be mixed and layered, such as niacinamide and AHA and BHA acids. Since acids are most often found in a medium with a pH value of 3-4, and niacinamide 5-7, mixing them would result in them canceling each other out. In other words, niacinamide would raise the pH of the acids, making them less effective, and the acids cause the conversion of niacinamide to niacin, which can cause transient redness of the skin. It is necessary to wait at least 30 minutes between the application of acids and niacinamide or to use them at different times of the day; niacinamide in your morning routine, and acids in your night routine.
While we were formulating our product, we took special care that in ensuring that they’re pH-optimized.
Choose wisely, because a well-adjusted pH medium of the product is the way to healthier skin.
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- Pullar J, Carr A, Vissers, M. The Roles of Vitamin C in Skin Health, Nutrients, 9(8) (2017) 866.