High summer asks a lot of a face. Sunscreen before you leave the house, sweat through the afternoon, the dry chill of air conditioning indoors against the heat waiting outside. It is the season when you want to wash your face several times a day.
Cleansing away sweat and sunscreen is worth doing. But washing does not have to mean emptying the skin of everything it holds. Cleansing lifts away soil and, at the same time, acts on the environment of the skin's surface. The harder you chase that squeaky, stripped feeling as proof of clean, the more you can wash away the balance the skin was quietly keeping.
Healthy skin, though it varies with age and with the part of the body, generally keeps its surface mildly acidic. In a multicenter study of 330 people, surface pH measured after participants had paused showering and cosmetics for 24 hours averaged below 5. Because skin pH shifts with the site measured, with age, and with surroundings, it would be a mistake to insist that everyone's skin sits at exactly 5.5.
That acidity is more than a number. The enzymes that process the lipids of the stratum corneum and the enzymes that govern how skin cells bind and shed work best at different pH levels; the acid environment keeps those processes in balance, and it also helps shape the conditions in which the skin's resident microbes live.
Cleansing doesn't end at removal. Even washing with water alone can shift surface pH for a while, and the size of that shift — and how long the skin takes to return — depends on the cleanser. In a study that tracked skin pH through repeated washing with an alkaline soap and a mildly acidic cleanser, both raised pH right after washing, but the soap raised it more, and the skin was slower to come back. With each repetition, the gap between the two widened.
The value of a mildly acidic wash is not that it adds acid to the skin. It is that it chooses cleansing conditions close to the skin's own, so there is less for the skin to recover from once you are done.
Even so, the words "mildly acidic" on a label do not finish the job. At a skin-friendly pH, the surfactants a cleanser uses — which ones, at what concentration, in what combination — still change how it meets the skin. Comparative studies have found that being mildly acidic does not, on its own, guarantee gentleness. Mildness is decided together by pH, by the type and level of surfactants, by any humectants, by water temperature, and by how often and how long you wash.
Mildly acidic is an important condition for a good cleanser. It is not the only one.
Wash away the sweat and sunscreen of summer — but there is no need to scrub the skin over and over, or to use very hot water, to prove it is clean. The American Academy of Dermatology notes that even in hot, humid weather, sun, pools, and air conditioning can leave skin dry and irritated, and it recommends a gentle cleanser and lukewarm water. Sweat is better blotted away with a clean cloth than rubbed off hard, and if skin feels tight or stings after washing, the water temperature, the cleanser, and the number of washes are worth revisiting.
What matters as much as the washing is the state the skin is left in afterward.
A mildly acidic wash is not a technique for adding something to the skin. It is a way of disturbing, as little as possible, the environment the skin already had while still getting genuinely clean.
That is why Olivarrier looks not only at how well a cleanser washes, but at the condition the skin is left in once the washing is done.
References
- Lambers H, Piessens S, Bloem A, Pronk H, Finkel P. Natural skin surface pH is on average below 5, which is beneficial for its resident flora. International Journal of Cosmetic Science. 2006;28(5):359–370.
- Hachem JP, et al. Sustained serine proteases activity by prolonged increase in pH leads to degradation of lipid processing enzymes and profound alterations of barrier function and stratum corneum integrity. Journal of Investigative Dermatology. 2005;125(3):510–520.
- Korting HC, Kober M, Mueller M, Braun-Falco O. Influence of repeated washings with soap and synthetic detergents on pH and resident flora of the skin of forehead and forearm. Acta Dermato-Venereologica. 1987;67(1):41–47.
- Gunathilake HMDR, Sirimanna GMP, Schürer NY. The pH of commercially available rinse-off products in Sri Lanka and their effect on skin pH. Ceylon Medical Journal. 2007;52(4):125–129.
- Hawkins S, Dasgupta BR, Ananthapadmanabhan KP. Role of pH in skin cleansing. International Journal of Cosmetic Science. 2021;43(4):474–483.
- Cowdell F, et al. Skin cleansing without or with compromise: soaps and syndets. Molecules. 2022;27(6):2010.
- American Academy of Dermatology. 12 summer skin problems you can prevent.
High summer asks a lot of a face. Sunscreen before you leave the house, sweat through the afternoon, the dry chill of air conditioning indoors against the heat waiting outside. It is the season when you want to wash your face several times a day.
Cleansing away sweat and sunscreen is worth doing. But washing does not have to mean emptying the skin of everything it holds. Cleansing lifts away soil and, at the same time, acts on the environment of the skin's surface. The harder you chase that squeaky, stripped feeling as proof of clean, the more you can wash away the balance the skin was quietly keeping.
Healthy skin, though it varies with age and with the part of the body, generally keeps its surface mildly acidic. In a multicenter study of 330 people, surface pH measured after participants had paused showering and cosmetics for 24 hours averaged below 5. Because skin pH shifts with the site measured, with age, and with surroundings, it would be a mistake to insist that everyone's skin sits at exactly 5.5.
That acidity is more than a number. The enzymes that process the lipids of the stratum corneum and the enzymes that govern how skin cells bind and shed work best at different pH levels; the acid environment keeps those processes in balance, and it also helps shape the conditions in which the skin's resident microbes live.
Cleansing doesn't end at removal. Even washing with water alone can shift surface pH for a while, and the size of that shift — and how long the skin takes to return — depends on the cleanser. In a study that tracked skin pH through repeated washing with an alkaline soap and a mildly acidic cleanser, both raised pH right after washing, but the soap raised it more, and the skin was slower to come back. With each repetition, the gap between the two widened.
The value of a mildly acidic wash is not that it adds acid to the skin. It is that it chooses cleansing conditions close to the skin's own, so there is less for the skin to recover from once you are done.
Even so, the words "mildly acidic" on a label do not finish the job. At a skin-friendly pH, the surfactants a cleanser uses — which ones, at what concentration, in what combination — still change how it meets the skin. Comparative studies have found that being mildly acidic does not, on its own, guarantee gentleness. Mildness is decided together by pH, by the type and level of surfactants, by any humectants, by water temperature, and by how often and how long you wash.
Mildly acidic is an important condition for a good cleanser. It is not the only one.
Wash away the sweat and sunscreen of summer — but there is no need to scrub the skin over and over, or to use very hot water, to prove it is clean. The American Academy of Dermatology notes that even in hot, humid weather, sun, pools, and air conditioning can leave skin dry and irritated, and it recommends a gentle cleanser and lukewarm water. Sweat is better blotted away with a clean cloth than rubbed off hard, and if skin feels tight or stings after washing, the water temperature, the cleanser, and the number of washes are worth revisiting.
What matters as much as the washing is the state the skin is left in afterward.
A mildly acidic wash is not a technique for adding something to the skin. It is a way of disturbing, as little as possible, the environment the skin already had while still getting genuinely clean.
That is why Olivarrier looks not only at how well a cleanser washes, but at the condition the skin is left in once the washing is done.
References