In a previous post the Left Brain talked about how to check the pH of your cosmetics. But why should you care about the pH of products in the first place? I think everyone understands pH is a measure of how acidic or basic a product is (on a 14 point scale where one is the most acidic and 14 is the most basic or alkaline.) But what does pH really mean for your beauty products?
The importance of pH
Many people think their cosmetics need to be “pH balanced.” This usually refers to a product having a pH that’s adjusted to be close to the pH of your skin. In actuality that’s more of a marketing myth then it is a real issue for you. That’s because your skin restores its own natural acid mantle within a few minutes of any product application. So you don’t really need to look for pH balanced products but products DO have to have the correct pH. The correct pH ensures that products can deliver the following properties:
- Exfoliation (from an AHA)
- Preservation
- Conditioning agent deposition
- Relaxation
- Color deposition
- Styling resin removal
- Hair removal
In some rare cases the wrong pH can even cause dangerous side effects. We recently wrote that ingredients used in soft drinks (and maybe some Vitamin C cosmetics) can react to form free benzene (a carcinogen) when the pH is below 2.
You can’t tell pH from an ingredient list
Finally, remember you can’t judge the pH of a product just by looking to see if there is an acid or base on the ingredient list. That’s because acids (like citric acid) and bases (like sodium hydroxide) are often added as processing aids. That means they are used at low levels to neutralize another chemical in the formula and they are no longer present in their “active” form. Sodium hydroxide at a very low level in a pH neutral product poses no danger to your hair or skin. However, that same ingredients at a high concentration and high pH can literally dissolve hair and burn your skin.
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My favorite thing about this site is that you guys explain the beauty chemistry. Thank you for including the link to the testing article you did before (love the link to the litmus testers) and I wonder how practical it would be to ask if you guys could consider writing a guide for those of us who are nuts and plan to buy litmus test strips so we know what the pH should be for our products.
I have a doubt about this, how can we regulate pH in a DIY formula like a vitamin C serum?.
@AleV: You can lower pH by adding an acid like citric acid. You can raise pH with a base like TEA or sodium hydroxide.