Cleopatra bathed in sour milk and the ladies of the French court used wine (this contained tartaric acid) to improve their skin. Fortunately for us we can enjoy our wine as a drink and ingredients such as lactic acid and tartaric acid are, along with glycolic acid and salicylic acid, available in various concentrations. What all these substances have in common is that they exfoliate. An exfoliating substance removes the uppermost dead skin cells.
There are many ingredients with exfoliating properties. These are fruit acids (alpha hydroxi acids) and salicylic acid (beta hydroxyl acid). The most common fruit acids are Glycolic acid and Lactic acid. But there are also Mandelic acid, Tartaric acid, Malic acid and Citric acid. These AHA's and BHA are derivatives of natural products:
- Glycolic acid from honey and sugar cane
- Lactic acid from milk
- Salicylic acid from the bark of a willow tree
- Malic acid from apples and pears
- Citric acid from oranges and lemons
- Mandelic acid from almonds
The fact that these exfoliating substances originate from fruit has ensured that fruit extracts are regularly used in beauty products. Unfortunately these are not the same thing. In fact some of these extracts can cause much irritation to skin without having any beneficial effect. Yet through the positive association that they generate, the beauty industry likes to add them to their ingredient lists.
Salicylic acid and glycolic acid
The two most widely researched exfoliating ingredients are glycolic acid and salicylic acid. With very promising results, if used properly and in appropriate concentrations! Glycolic acid penetrates deeper into the skin but can also cause more irritation. It is especially suitable for the more mature or dry skin which is less sensitive. Salicylic acid is fat soluble and penetrates deep down into the pores. This makes it more suitable for oily skin which is prone to spots/acne. Because it causes less irritation it is more suitable for sensitive skin. Considering an exfoliant can irritate the skin somewhat when first used it is important that the product contains a calming ingredient. You can also use an exfoliant in combination with a product containing calming ingredients. I've written a more detailed blog about glycolic acid and there will be one to follow about salicylic acid.
The requirements: percentages and pH values
In order for it to be effective sufficient concentrations of active substances are crucial: Glycolic acid more than 5% and Salicylic acid more than 1%. These ingredients are used in concentrations of up to 70% for peelings, but they must be used under medical supervision so are therefore not freely available.
The pH value of an exfoliant is also very important. If the pH is too high the substances become neutralised and they lose their effectiveness, whilst if the pH is too low the substances irritate the skin (Goldberg, Light years younger).
I wrote previously about 'the exfoliant as part of the personal step by step plan'. You can also read on my blog about 'the best way to use your exfoliant' and what happens if you don't use it properly.
(Dr. Jetske Ultee-Research Physician and Head of The Skin Therapy Department)