In the 1890s science discovered that the skin had an acidic surface. Then, in 1928, Schade and Marchionini suggested that the function of the low pH film was to protect the skin from microbes, and coined the term ‘acid mantle’ to describe it. Even though they did not explain how the acid mantle achieved the protective effect, their idea was largely accepted and repeated throughout the literature of the day.
Many soaps and detergents of the time were quite alkaline in nature, and their harmful effects on the skin were well known by consumers and dermatologists alike; so the concept of the ‘acid mantle’ went some way to explain why this was the case. You might think that cosmetic companies would jump on this fact and use it to persuade consumers to exchange soap for a skin cleanser; however, this does not generally appear to have happened. One possible reason for this may have been that many cosmetic companies were also in the soap business, with some of them also using soap in their cleansing routines. Secondly, most cosmetic houses were fighting a cleansing war on two fronts. As well as suggesting that consumers use cleaners rather than soap, they were also trying to wean them off cleansing with cold cream. To do this they needed to convince their customers that a specialist cleanser provided a better solution than either product.
The Helena Rubinstein scientific washing preparations accomplish what could never be done by creams or soap alone! They not only cleanse deeply—they impart an animated, transparent look to the skin.
Rather than take a negative approach on two fronts, Beauty Houses concentrated on the more positive ‘soothing’, ‘feeding’, ‘beautifying’ and ‘nourishing’ aspects of their products, thus avoiding unpleasant subjects like acids and microbes.
Alkalinity and acidity only get mentioned in advertisements for cosmetic products where the pH could be considered to be a potential problem, namely in soaps and shampoos; however, this marketing trend does not begin until later in the twentieth century. It was not that cosmetic companies were unaware of the presence of the ‘acid mantle’ or the harmful effects of alkaline materials on the skin, it’s just that most did not consider it to be a good selling point. Even so, although perhaps unconvinced that the ‘acid mantle’ was marketable, many thought it prudent to keep the pH of their products as close to that of the skin, or as neutral, as possible.
In regard to negative advertising, one soap company was not so squeamish. Despite protests from cosmetic houses, Lever Brothers took to describing the dangers of acquiring ‘Cosmetic Skin’ in their advertisements for Lux Toilet Soap; the cure for which was, of course, Lux soap and water. Apparently “Romance comes to the girl who guards against Cosmetic Skin”. Lever Brothers ran this marketing line in their Lux advertising for a few years in the 1930s using a range of stage and screen stars as support.
See also: Cosmetic Skin
Although it was ignored in advertising by most cosmetic houses, some did try to use the acid mantle as a marketing tool. Two different approaches were tried, neither of which was particularly successful.
One company suggested that an acid skin might need treatment. They advocated the use of a cream containing Milk of Magnesia (suitably emulsified) to neutralise the acid (deNavarre, 1941, p. 133). The product was short-lived, presumably as sales were low.
The more common approach was to support the acid mantle by manufacturing and marketing acid creams. These products had a few technical and marketing restrictions that needed to be overcome. Chemically, the presence of a mild acid meant that soap could not be used as the emulsifying agent as the acid would decompose the soap so alternatives had to be used. Two suggested formulas for acid creams are given below:
Acid Cream 2 % Sodium cetyl sulfate 4.0 Cetyl alcohol 8.0 Ozokerite, bleached 2.5 Mineral oil 12.0 Diethylene glycol 5.0 Lemon perfume compound (for creams) 0.5 Glycerophosphoric acid 2.5 Distilled water 65.5
Formula 27 % Wool wax 3.0 Lanolin, anhydrous 8.0 Stearyl alcohol 2.0 Petrolatum 37.0 Glycerol 4.0 Lactic acid 1.5 Water 44.5
Procedure: Melt the wool wax, lanolin, stearyl alcohol, and petrolatum and bring to a temperature of 55°C. Add glycerol and lactic acid to the water and heat to 57°C. Add the water solution to the fats with good agitation. When all the water has been added, continue stirring until the temperature has dropped to 45 to 50°C., and then add the perfume. Pass the cream through a colloid mill (Eppenbach type).
There were also marketing difficulties. Consumers generally do not like the idea of putting acid on their skin, an idea that the Milk of Magnesia formulation hoped to capitalise on. This is still true today and many acidic products, like shampoos, are still referred to as non-alkaline rather than acidic. For this reason the creams were sometimes marketed as ‘lemon creams’ which meant that the formula had to contain citric acid or be perfumed with oil of lemon to avoid problems with regulatory authorities.
In general, ‘acid creams’ never really caught on with the public and are restricted today to quasi-medical creams for individuals with specific skin conditions. Meanwhile, many ‘soaps’ and shampoos had learnt their lesson and began advertising themselves as ‘alkali-free’ or ‘non-alkaline’.
Acidic cosmetics ‘time in the sun’ had to wait until the end of the twentieth century, when alpha-hydroxy acids (AHAs) began to be added to cosmetic products. Marketed as ‘fruit acids’ these were generally milder versions of some of the chemical peels that had been previously been used by dermatologists and plastic surgeons to remove the signs of skin roughness, ageing and pigmentation. Like many things, they moved from the medical profession, to the salon, and then on to general distribution over the counter. In their heyday, they penetrated all aspects of the skin care market including cleansers, moisturisers and masks. The considerable discomfort that could occur while using these products is a measure of the strength of the desire many consumers had to look younger; it was stronger that their fear of acids or their need for comfort.
Typically AHAs, such as glycolic, malic, citric and lactic acids, make up less than 10% of the formulation. This was not always the case and products with much higher percentages were made up for use in salons. The pH of the products also varied but it was generally agreed that commercial products should not get down below a pH of 3.0 (Winter, 2005, p. 61) although whether salons stuck to this limit is open to question.
Being acidic, these products – and the BHAs (beta-hydroxy-acids) that followed them – can be dangerous if a formulation with a very low pH is left on the skin for too long. Fortunately, as with alkaline soaps, as long as exposure is short and the skin is not damaged, natural body processes return the skin’s pH to a normal levels soon after use and the ‘acid mantle’ is restored.
Updated: 4th November 2013
deNavarre, M. G. (1941). The chemistry and manufacture of cosmetics. Boston: D. Van Nostrand Company.
Poucher, W. A. (1932). Perfumes, cosmetics and soaps, Vols. 1-2 (4th ed.). London: Chapman and Hall.
Sagarin, E. (Ed.). (1957). Cosmetics: Science and technology. New York: Interscience Publishers, Inc.
Thomssen, B. S. (1947). Modern cosmetics (3rd ed.). New York: Drug & Cosmetic Industry.
Wilkinson J. B., & Moore, R. J. (Eds.). (1982). Harry’s cosmetology (7th ed.). New York: Chemical Publishing.
Winter R. (2005). A Consumers dictionary of cosmetic ingredients (6th. ed.). New York: Three Rivers Press.