The Highs and Lows of pH

Contact Author Kirsten Sheridan December 2006 issue of Skin Inc. magazine


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The defenses are up, the barrier is intact and the level of protection is high. Yes, the skin is being referred to—healthy skin, that is. There are many contributors to the formation of healthy skin, but of great importance is its pH level.The human body’s entire system depends upon maintaining a pH balance, which promotes its general health and well-being. In relation to the skin, however, changes in pH can have significantly dramatic effects. Healthy pH provides the stratum corneum with a slightly acidic environment. Poor product choices, harsh exfoliants and physical trauma all greatly affect this acidic microniche that offers protection from an offensive world.

Concept of pH

pH is an acronym for the power, or potential, of hydrogen. Simply put, the power of hydrogen indicates the acidity or alkalinity of a solution. This is measured in units called logarithms, using a scale known as the pH scale. This runs from pH 0–pH 14. A solution that is highly acidic will have a lower pH number. So, for example, battery acid, which is highly acidic, measures around pH 1. Acidic solutions contain primarily hydrogen ions (H+), so a pH 1 solution would be composed mostly of hydrogen ions. At the opposite end of the scale, solutions mainly are made up of hydroxyl ions (OH-). So, for example, lye, which is in the range of pH 13–14, is highly alkaline. pH neutral denotes the middle of the scale and is represented by pH 7. A neutral pH solution contains an equal number of hydrogen and hydroxyl ions, and is neither acidic nor alkaline. Distilled water is a good example of a pH-neutral solution.

When measuring pH, the unit of logarithms expresses a tenfold change from the previous concentration, similar to the Richter scale that is used to measure earthquake activity. For instance, a solution measuring pH 3 indicates 10 times fewer hydrogen ions than a pH 2 and is, therefore, 10 times less acidic in nature. Think of hydroxyl acid preparations used for peeling and exfoliation. A hydroxyl acid preparation of pH 2 versus pH 3 will provide very different results.

The acid mantle


One of a human’s first lines of defense is the acidic environment created in the upper layers of the epidermis, courtesy of the acid mantle, which is a protective outer coating. The body’s acid mantle is a key mechanism that keeps out unwanted visitors, particularly of the bacterial variety. The environment is full of harmful and not-so-harmful bacteria that are just waiting for an open invitation to cause havoc on the skin. The acid mantle’s slightly acidic pH of 4.5–5.5 wards off harmful bacteria, restricting or preventing its growth on the skin. Fortunately, the bacterial flora that is nonpathogenic—or beneficial to the skin—thrives in the acidic environment created by the acid mantle. If it is compromised and a more neutral pH develops, bacteria such as staphylococcus and fungi such as candida may proliferate.

The acid mantle is formed from free fatty acid secretions from the sebaceous glands, lactic acid from the body’s eccrine sweat glands and microbial metabolites that rendezvous in the stratum corneum. Enzymes and specialized proteins also are involved in the formation of this essential acidic environment. This carefully orchestrated meeting provides the healthy pH balance needed to protect and defend the skin, which is so essential to barrier function. Due to changes in the skin as people age, its pH may become slightly elevated.

Although one of the most recognized mechanisms of the acidic stratum corneum is antimicrobial defense, that is only part of the story. Acidity plays a major role in restricting the initiation of the inflammatory response within the skin. Clients with skin diseases and disorders such as dermatitis display an elevated pH level. This is apparent in clients with inflammation, either from disease or from trauma. An elevated pH can stimulate cytokine activation; however, this alone does not create inflammation.

The acidity created by the acid mantle plays a role in preventing premature desquamation of the stratum corneum. In addition, it is essential in the formation of the epidermal permeability barrier.

Despite fantastic ingredients, new technology, education and a health-conscious world, there still are people who damage their stratus corneum—from skin pickers to soap junkies who can strip and dry the skin’s natural defenses by using harsh exfoliants, drying cleansers or too many products. Soap has an alkaline pH, which, when used regularly, dries the skin and leaves it feeling tight, as well as disrupts the acid mantle. Fortunately, this mantle is somewhat resilient and can repair itself in a matter of hours, but constant, prolonged abuse becomes increasingly difficult to repair.

To ensure a healthy, balanced protective barrier, selecting the right products is essential. Beginning with the cleansing process, advise clients to use a pH-balanced cleanser. This will go a long way toward ensuring the health of the skin. Manufacturers often add buffers to a formulation in order to counteract the negative effects of an alkaline pH, creating a pH value that is as close to healthy skin as possible. Clients should be encouraged to use pH-balanced products.

However, there are instances during skin care treatments in which the acidic environment created by the acid mantle hinders the body’s ability to gain the desired results. For example, this occurs when performing desincrustation. Whether done manually or by utilizing the negative polarity of galvanic current, a desincrustation solution should be used. These are slightly alkaline in nature, so they soften and dilate the follicles, making manual extractions easier. Built-up dirt and debris in the follicles are softened by a process called saponification. However, after performing extractions, it is essential to return the skin to its naturally balanced pH range, tightening the follicles and restoring the acid mantle to its former glory. Using the positive pole of galvanic or applying a product designed to rebalance the skin’s pH can achieve this.

Measuring pH

Measuring the pH of a solution is easy to do, and can be accomplished by using a pH pencil or testing strips. Utilizing a pH pencil as a retail tool allows you to educate clients about the importance of pH-balanced product choices for achieving healthy skin. Testing products that clients may have at home will help them to weed out poor product choices. Setting up a workstation where clients can test a product’s pH while waiting for their appointments is a fun and engaging way to encourage questions.


Another consideration when thinking about pH is water. Water is used in face and body treatments, showering, mixing products, filling steamers and soaking steam towels. You probably are aware of the negative effects of using tap water in your steamers—sediments and mineral deposits collect on the element and result in the malfunction of the unit. Distilled water prevents this. It has a neutral pH of 7, while tap water is alkaline, although the degree of alkalinity depends upon your location. Knowing the negative effects of prolonged alkalinity on the skin, it could be concluded that distilled water is a better choice due to its reduced chemical content and closeness to the skin’s natural pH.

Before you embark on a distilled water-only policy, however, take a look at the bigger picture. It is unlikely that your clients are using distilled water at home for cleansing and skin care purposes, and utilizing distilled water in the treatment room can be costly and time-consuming. However, installing filters on your taps and showers will go a long way in reducing the harsh chemicals found in the water supply that offer no skin benefits whatsoever.

Internal pH

Although the importance of maintaining the acidic PH of the stratum corneum now is understood, maintaining internal pH balance is crucial, as well. As skin care professionals, you work topically, but you also can educate clients about their general health and encourage them to seek more information that will help them in their quest for it. Aging is a huge factor for today’s clients, and understanding that internal pH plays a part in the aging process is key to helping them achieve overall well-being. Internal body pH should range from 6.8–7.4 in order to maintain cellular health. Although the trillions of cells in the body are acidic in nature, they are surrounded by alkaline body fluids. For example, the optimum pH of the blood is 7.45, while stomach acid is highly acidic at pH 1.5.

Just as you can test the pH of the skin, you also can test the overall pH of the body. pH strips can be used to test either your urine or saliva, although the most reliable results come from saliva. Always test first thing in the morning before brushing your teeth, or eating or drinking anything. Health food stores sell pH testing strips specifically for this purpose—they do not display the full pH range, but span pH 4.5–7.5.


Many people have an overly acidic internal pH range, but, fortunately, just as the acid mantle has the ability to repair itself, the body has mechanisms that enable its internal chemistry to maintain homeostasis. There are buffers that help to restore the acid/alkaline balance when it is out of whack. However, these sometimes are not enough. If the body becomes too highly acidic, a condition called acidosis occurs. Toxins build up, and cellular degradation results.

A piece of the puzzle




J Barron, Lessons From the Miracle Doctors, Baseline of Health (April 2002)

P M Elias and K R Feingold, Skin Barrier, Taylor & Francis Group (2006)

G J Tortora and S R Grabowski, Introduction To The Human Body: The Essentials of Anatomy and Physiology, Wiley (2004)

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