The aqueous film on the surface of the skin is called the acid mantle or hydrolipic film. It is the skin’s primary defence against bacteria and is composed of sebaceous oil, sweat and epidermic secretions. The film is slightly acid and serves many essential functions.
The film acts as an antiseptic, helping to prevent the growth of bacteria that cannot survive in an acid environment, and helps prevent toxic matter from being absorbed into the skin. In addition to helping buffer the action of acid and alkaline chemicals, the film acts as the skin’s primary lubricant, controlling the hydration of the Stratum Corneum.
Acidity or alkalinity of the skin surface is directly related to the chemical balance of the hydrolipic film as well as exuded carbonic acid and is measured by the level of pH (potential hydrogen) present.
What does a pH-value measurement mean?
The measurement of the pH-value covers a very important characteristic of an aqueous solution: its acidity or basicity (alkalinity).
This value is determined by the amount of hydrogen ions (H+, protons) and hydroxide ions (OH-). According to its simplest definition, introduced by Soren Sorensen in 1909, pH is the negative logarithm of the molar concentration of hydrogen ions: pH = -log [H+]
A pH -value may fall anywhere on a scale from zero (strongly acidic) to 14 (strongly basic ‘alkaline’), with a value of 7 representing neutrality. An example of such a substance is distilled water, measuring a pH of 7 on the scale.
The pH-value measurement on the skin’s surface
As the skin’s surface with its excretions and its moisture content is very similar to an aqueous solution, a direct pH-value measurement on the skin’s surface is possible. The average pH-value for women is 5.5 and for men, it is slightly lower (approx, 5).
The pH-value of course, varies depending on the tested skin area, different exogenic and endogenous factors. This means the pH-value of skin is in the acidic range, it is also called the “acid mantle” (hydrolipic film) of the skin. It influences the bactericide and fungicidal effect of the skin, which is very important for health.
The more acid the skin is the lower the pH-value reading, consequently, the more alkaline the skin, the higher the pH reading. Extremes of skin pH-value range between 4.4 (sensitive) to 6.5 (oily).
Factors that will change the pH-value from day to day are menstruation, antibiotics, anti-fungal medication, alcohol, high acid diet, cold medication, just to name a few.
The pH-value measurement of products
Permanent maltreatment of the skin with cosmetic and pharmaceutical products or chemicals may lead to desiccation of the skin indicated by damages and premature ageing.
Normally, soap solutions have pH-values above pH 7. A healthy skin faced with such a high pH-value after washing will only relax after a short period of (20min-100minutes). However, the skin needs up to 5 hours approximately to regain its original pH-value. A sensitive skin may adjust to a higher pH-value over a longer period that considerably influences it protection function.
Cosmetics with an undesirable high pH-value that remain on the skin will cause stress to the skin and limit its protection function. This brings us to the importance of knowing the client’s skin pH-value and the pH-value of products she has been applying. This will assist us in establishing the first priority skin condition and possibly the cause of the said condition.
Many of our clients are susceptible to media marketing and consequently buy and use many domestic retail products. Unknowingly stripping the delicate acid mantle and causing skin conditions like Lipid dryness, dehydration, slowness to heal, congestion and so on.
On this note and armed with the latest technology for testing the pH-value of skin and products, I hit the supermarket for a variety of soaps that have been a thorn in our sides for years.
I tested as many as I could and using the scale below, I share with you my findings.
Palmolive Essential soap * 7.4
Dove soap * 7.4
Liquid soap with aloe * 7.9
Cleopatra * 9.3
Imperial leather red * 9.4
Palmolive dish wash * 9.4
Knights castile * 9.5
Palmolive gold * 9.6
Lux * 9.6
Imperial leather white * 9.6
Down to earth wash * 9.6
Johnsons baby soap * 9.7
Hotel soap * 9.7
Sard soap * 9.7
Palmolive * 9.8
Pears * 9.8
Simple soap * 10
I believe this information will not only be an update in your education about pH-value but also give you some ammunition when talking to your clients about their home care and the importance of using quality beauty therapy only products.
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