Acid mantle – Why pH value is crucial

What is the acid mantle?

We already provided a brief explanation of the acid mantle in our article "colibri skincare ABC: Skincare Terms and Their Meanings" . However, since the acid mantle is one of the most important protective factors for our skin, it deserves its own article.

The acid mantle is also known as the hydrolipid film. It lies on the outermost layer of the skin, the stratum corneum, the outermost layer of the epidermis. The hydrolipid film protects the skin from harmful bacteria and prevents them from colonizing and multiplying. As the name "acid mantle" suggests, it has an acidic pH. The exact pH value of the hydrolipid film can vary (more on this below). It ranges between 4.5 and 6. On average, the skin's pH is around 5.5. However, as mentioned, this value varies from person to person, and different sources cite different values.

Composition of the acid mantle

The alternative name for the skin's acid mantle, hydrolipid film, already reveals much about its composition. It consists of aqueous (hydro) and fatty (lipid) components. Such a mixture of fat and water is called an emulsion. The water component of the hydrolipid film is made up of sweat and naturally occurring acids on the skin, such as lactic acid. The fatty component, on the other hand, consists of skin lipids , namely sebum and fatty acids. A mixture of sebum and sweat might not sound like something you'd necessarily want on your skin at first glance. However, both are completely natural components of healthy skin, which we need to a certain extent to maintain that health. An overproduction (as well as an underproduction) of sebum, sweat, or both is understandably unpleasant and can easily be remedied with appropriate skincare products. A healthy mix of sebum and sweat is essential for the skin's acid mantle.

Excursion: pH value

To understand the skin's acid mantle, a little basic knowledge about pH is helpful. Some of the basics might be familiar from chemistry class. The pH scale ranges from 0 to 14. As we established in the first section, the skin's pH is around 5.5; it's slightly acidic, as all values ​​below 7 are in the acidic spectrum. This value of approximately 5.5 is also what's meant when something is described as "pH-neutral for the skin." The truly pH-neutral value is exactly in the middle of the scale, i.e., a pH of 7. This corresponds to the pH of pure water. Above this value, the basic spectrum begins. This is also alternatively referred to as alkaline.

For those who want to delve a little deeper: The pH value indicates how many positively charged hydrogen ions a substance contains. If a substance has many of these and tends to release them, it is acidic. Conversely, if a substance has many negatively charged ions and tends to accept positive hydrogen ions, it is a base. Basically, it's quite simple.

Varying pH values ​​of the hydrolipid film

After our brief explanation of pH, we now return to the topic that the exact pH value of the skin's acid mantle can vary. This variance is related to several factors. First, there's skin tone; the pH value of lighter skin is slightly lower than that of darker skin. Another factor is gender. Women have a higher pH value than men. Then there's the question of where on the body the pH value is measured, as it isn't uniform even on the same body. Under the armpits, for example, the pH value is higher. Finally, age also plays a role. With increasing age, the pH value automatically rises and should be adjusted downwards. Babies, however, have to develop their entire microbiome after birth. This development, until their skin reaches a stable pH value, lasts approximately the first year of life.

Unfortunately, you can't determine your skin's pH level at home with a convenient test kit. However, it can easily be determined by a doctor.

Protection and microbiome

We've already established that the acid mantle is an internal protective mechanism of our skin. This protection takes place on various levels. The hydrolipid film is closely linked to the skin barrier. If the acid mantle is damaged, the functionality of the skin barrier also decreases. The hydrolipid film therefore helps to maintain the barrier function. It also ensures that the skin can carry out its regeneration processes unhindered and remains optimally hydrated during this time.

Furthermore, the acid mantle contains countless microorganisms that together form the so-called microbiome. This includes the beneficial bacteria that our skin needs. Among these bacteria, there are those we need and those that are harmful. The latter are repelled by the acid mantle, preventing them from causing damage. The acidic environment offers pathogens like viruses, bacteria, and fungi no breeding ground for proliferation; in fact, it makes it particularly inhospitable for them. All in all, a very clever protective system for our skin.

Skin reactions due to excessively high pH levels

We've already explained the difference between pH-neutral skin, which is slightly acidic, and true pH neutrality. If the skin's pH value is significantly higher than 5.5 or even tends towards the pH-neutral value of 7, something is wrong. Skin diseases can often be the cause. In this case, consulting a doctor is definitely advisable. If there are no contraindications to using conventional active ingredient cosmetics, the pH value can be corrected back towards the desired level with acidic skincare products.

Just like our skin barrier, the acid mantle is a fragile structure. An imbalance can easily occur, leading to a permeable skin barrier and a variety of symptoms when the pH is outside the optimal range. In a system as complex as human skin, everything is interconnected, and an imbalance can quickly trigger a chain reaction, much like knocking over a row of dominoes. What specific symptoms does the skin develop when the acid mantle and skin barrier are compromised? The skin can react in two extremes: it becomes either very oily (recognizable by its characteristic sheen) or very dry. In both cases, further typical reactions of overly alkaline skin can occur, such as irritation, redness, itching, and increased blemishes.

Fruit acids are an effective way to restore overly alkaline skin to its normal acidic state. Read on to learn everything you need to know about hydroxy acids, which include fruit acids.

Hydrolipid film and skin cleansing

Let's now turn to a point we already discussed regarding the skin barrier: What about our skin's protective systems and skin cleansing? Facial cleansing also partially removes the acid mantle. However, cleansing is an important factor and shouldn't be skipped. Although the microbiome and the components of the acid mantle are essential for the skin, excess sebum, dead skin cells, as well as makeup and sunscreen should be removed regularly. With a few simple measures, you can avoid damaging your hydrolipid film even with regular facial cleansing. It's important to note that while regular cleansing is beneficial, the acid mantle shouldn't be constantly washed away. A cleansing routine should be thorough, but it doesn't have to take forever. It's advisable to pay attention to the pH value when purchasing skincare products and to use either pH-neutral or slightly acidic products. As always, we advise against harsh surfactants or soaps and recommend mild surfactants instead.

After cleansing, toners can be used as the next step in your skincare routine to help restore the acidic pH of the skin's protective acid mantle. Our Revival Toner has a pH value between 4.5 and 5.5. The Aloe Vera Spray is also suitable as a toner and offers a pH value between 3.2 and 4.2. Both products are therefore perfect for ensuring an acidic start to your skincare routine.

The right care for a healthy acid mantle

We've already given you some skincare tips, such as using fruit acids and a toner. Aside from that, the most important thing to consider when choosing your skincare products is the pH value. It should be either skin-neutral or even slightly acidic. If the pH value tends towards alkaline, it can stress the skin and cause irritation. Ideally, the pH values ​​are listed on the product pages. Otherwise, you can usually just ask the manufacturer for this information.

To maintain the skin's protective acid mantle, it's important to always finish your routine with a protective moisturizer. A cream with a healthy mix of natural humectants and skin lipids is best for this. You can learn more about Natural Moisturizing Factors in our article "The Secret Behind Effective Moisturizing Care." As always, all skincare products should be suitable for your skin type .