The Hydrogen-Ion Concentration of the Surface of the Healthy Intact Skin

A comparative review of cutaneous pH

“…A pH of 7.0 is considered neutral. A pH of < 7.0 is considered acidic, whereas a pH > 7.0 is considered alkaline 11 . Therefore, as the pH number increases, the concentration of H + (acidity) decreases.…”

Human skin buffering capacity: an overview

“…The contribution of keratin to the buffering capacity of skin remains questionable. Keratin is an amphoteric protein with the ability to neutralize acids and alkalis in vitro (8–11, 17, 24–26) and hence may participate in skin's buffering capacity. Scales scraped from normal skin bind small amounts of alkali in vitro (27, 28).…”

Marchionini’s Acid Mantle Concept and the Effect on the Skin Resident Flora of Washing with Skin Cleansing Agents of Different pH

“…As early as 1892, Heuss [7] had come to the conclusion, still valid today, that, "The entire skin surface of healthy subjects shows an acidic reaction, although the degree of acidity will vary depending on the site involved." Equally, in 1923, Sharlit and Scheer [25] had found a pH of 5.5 when measuring in the antecubital fossa. It was not the actual values -of between 3.0 and 5.0 -found by Marchionini that make his findings so revolutionary; indeed, the pH values reported strike us today as quite improbably acid, considering the conclusions of a recent review paper [1] that, "The analysis of all the studies quoted yields a representative (mean) pH of human skin in the range of 5.4-5.9."…”

“…It was not the actual values -of between 3.0 and 5.0 -found by Marchionini that make his findings so revolutionary; indeed, the pH values reported strike us today as quite improbably acid, considering the conclusions of a recent review paper [1] that, "The analysis of all the studies quoted yields a representative (mean) pH of human skin in the range of 5.4-5.9." Where Marchionini was innovative was in his measuring technique: the use of electrodes -pioneered by him, and still the standard technique today -had been thought impossible only a few years earlier [25]. Apart from these technical innovations, Marchionini and his co-workers' outstanding contribution to science was their conclusion that the acid skin surface pH observed was related to the bacterial colonization of the skin.…”