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pH value of skin care products

The pH scale is used to measure acidity or alkalinity. The term pH describes the hydrogen ion (H+) concentration of a solution. As the hydrogen ion concentration increases, the pH decreases. A neutral pH is 7, an acid pH lies between 0 and 7, and an alkaline, or basic, pH lies between 7 and 14.

The stomach has a pH of 1 to 2 and is very acidic. Other acidic solutions include coffee at pH at pH 5, orange juice at pH 4, and vinegar at pH 3. Basic solutions include household ammonia at pH 11 and sodium hydroxide at pH 14.

The pH of the skin mantle ranges from 4.5 to 6 and is most often referred to as 5.5. This acid mantle is a fluid that bathes the top layer of the skin. It is composed of fresh sebum, sweat, and other dissolved cell secretions. It is generally believed that unless a cosmetic has a pH of 5.5, it is not compatible with the skin. Actually, some products would not be as effective if they had a reading of 5.5. For example, a cleanser formulated with a pH of 7 which is neutral will cleanse the skin better than a cleanser with a pH of 5.5. A moisturizer that is slightly more alkaline than our skin will have a softening effect. This makes it easier for the skin to absorb the beneficial ingredients in the moisturizer.

A cleanser that is very alkaline will alter the pH, which in turn may cause the skin to feel dry or "tight." Healthy skin, however, quickly returns to its normal pH. Skin pH also changes, depending upon season, time of day, and location on the body.

It is believed that the acid mantle acts as a natural defense barrier against skin infection. Because the fluid is acidic and thus possesses certain chemical characteristics, anything that radically changes the acidity of this fluid alters the defense barrier and so can cause beauty problems. When skin is healthy, it will have a good acid mantle.

Products that are formulated for acne skin are more acidic to help fight germ penetration. The acidic pH product will usually act as an anti-bacterial agent.