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How pH Affects the Formulation of a Product

By: Elaine Linker
Posted: September 28, 2012, from the October 2012 issue of Skin Inc. magazine.
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The acid mantle is a thin layer that helps skin remain healthier and free of blemishes. P. acnes bacteria is the major cause of blemishes when it reacts with oil and dead skin cells. Acid-formulated products and acid-based peels are often used as a primary treatment in resolving acne concerns, but often, due to the misunderstanding of pH, products that are too aggressive are used, resulting in redness and irritation. If the skin’s acid mantle is disrupted negatively, the skin becomes vulnerable to damage and infection. Helping to keep clients’ skin at the correct pH stabilizes skin’s barrier function by preventing water loss from the inside, as well as blocking the penetration of pollution and irritants from the environment.

The optimum pH

So, what is the optimum pH for effective skin health? Each skin concern needs a slightly different adjustment to the pH of the formula used, as does each set of products used to treat it. Often, a skin care protocol will include a combination of a few products formulated at various pH levels to optimize results. When formulating anti-aging products, it is common to include in the protocol a few products that help to increase exfoliation of the skin to minimize fine lines and wrinkles, and to increase hydration. The skin cell turnover rate for a client age 16–20 is, on average, 14 days. For every year a person ages beyond 20, it increases by one day. At age 30, it takes an average of 24 days for cells to turn over and reveal younger, healthier skin. At age 40, it takes 34 days and, at 50, well over a month at 44 days, resulting in the need for acid-based products.

Three things need to be considered when using a product and determining its ideal pH.

  1. What is the skin concern you are treating?
  2. What is the desired result of the treatment? Do you want to only increase exfoliation, or for the skin to actually peel?
  3. How much time will this product remain on the skin? Is it an in-spa treatment or an at-home product?

In-spa vs. home care

Everyday home-care products can vary from acidic to alkaline formulations. Professional in-spa use products are usually more acidic and can be formulated as low as pH 2, although the esthetic standard is no lower than a pH 3. Home-care products often range from pH 4–6, depending on whether they are cleansers or treatments that will remain on the skin for a longer period of time. Glycolic acid is the most popular of the acids used in formulations because of its smaller molecular size and ability to penetrate. Often, formulations will include a combination of several different acids. A common favorite combination is glycolic and lactic. Salicylic is often used alone or in combination with glycolic for the treatment of acne.

Lower pH products are used in the treatment of hyperpigmentation to obtain visible results by helping to accelerate the exfoliation of pigmentation in the epidermal layer. Try formulations that add holistic and alternative actives to the acid base in order to help prevent—as well as resolve—the current skin concern. Favorites for hyperpigmentation are arbutin, bearberry and kojic acid. Vitamin C, zinc, CoQ10 and retinoic acid help restore metabolic rejuvenation to damaged skin for healthier, long-term results.