Our skin is built up of many layers that are all fascinating to get to know, but today we're 'just' going to scratch the surface – the outermost, protective layer – also known as the acid mantle.
Appropriately NamedThe acid mantle is a fine film on the skin's surface that functions as a barrier. The pH of this layer is on the acidic side – more so than previously believed – but we'll get into that in a minute.
The advantages of having an acidic layer are all down to protection – keeping bacteria at bay and shielding us from viruses and other potential contaminants.
Men and Women Differ
A 2001 study showed that women have a significantly lower skin pH than men. So much so, the study concluded that "comparative studies on skin surface pH should be balanced with respect to gender". So, prior to what was previously believed, creating a pH-friendly skin care product that is equally suitable for men and women is always going to be a pH compromise.
We're Far More Acidic Then We ThinkThrough the years, I've seen many companies advertise the 'skin-friendly pH' of their products directly on the packaging – usually listed at around pH 5.5 - 6.0.
We now know that this is pretty far off the mark.
The International Journal of Cosmetic Science states the natural pH of the surface of skin is on average below 5 – more specifically around pH 4.7.
How Could They Get it So Wrong?It all comes down to the way they previously tested – not so much the method of testing as the timing. To measure the correct and natural pH of skin, it has to have been out of contact with water, cleansing agents or anything else for many hours.
Our skin reacts immediately to the pH of what it comes into contact with. For example: when we bathe or shower, we are exposing our skin to the (more or less alkaline) pH of soaps, shampoos and shower gels. We then rinse off with a neutral pH (water has a pH of about 7.0).
Just washing your face or bathing raises the pH of your skin measurably.
So, if a persons skin is tested for pH shortly after that person has bathed, the pH is going to measure incorrectly.
That's how they could get it wrong.
Knowing this, it suddenly makes sense why:
- Aloe vera is so well-tolerated and recommended for babies. Its pH of 4.5 is a natural match for skin.
- Skin tonic can make such a difference in the way the skin feels after washing. A properly formulated skin tonic will not only remove final remains of cleanser, but also rebalance the skin and help return it to it's natural pH.
- Just washing your face with 'plain old water' will knock it out of 'pH balance'. A balancing mist of hydrosol can help rebalance and restore the skin to its natural pH.
Find More about the Chemistry of the SkinChemistry of the skin and it's acid mantle – Susan Barclay Nichols
pH and Skin Care by Monika-Hildegaard Schmid Wendtner and Hans Christian Korting