Understanding how pH balance and sunless tanning affects skin
This page contains important information regarding skin pH and the effect that sunless tanning has on skin. Technicians and clients alike can benefit from the knowledge of the skin's natural balances and what results different products and solutions can yield.
What is pH?
To put it simple, pH is a measure of the acidity or basicity of a water solution. This measurement is called the hydrogen ion concentration and is indicated by a scale of 0-14. The lower the number the stronger the acidic nature, the higher the number the stronger the basic nature, with 7 being a completely neutral substance such as distilled water unexposed to air.
pH Levels of Common Substances
We've already mentioned how pH is measured, with completely neutral pure water being equally distant from both extremes of the scale. But without some common comparisons to everyday things, this scale of measurement may be a bit hard to grasp. It is explicitly specified that distilled/pure water is the neutral of this scale, as the chemical makeup of water is changed once exposed to the chemicals in the air, forming a weak carbonic acid with a pH of about a 5.5 value. Black coffee, cottage cheese and egg yolks are also items with a pH in this range, and are slightly acidic. Lemon juice and vinegar are some other more common acids you will find around the house, with a value of 2.0 and 3.0 respectively. Alkaline, or basic substances can also be commonly found, such as seawater with a 7.7-8.3 pH value, ammonia with a 10 pH value and Drain-O with a 12 pH value. Education on the basics of pH balance and levels can be helpful to learn as a tanning technician or customer, as products for sunless tanning can have slight imbalancing effect on a skin's natural pH measurement.
pH of the Skin
Skin pH values are usually quoted in an 4.5 to 6.0 range with a 5.5 being the most common value. The skin is said to have an acid mantle, meaning a thin layer is partially comprised of sweat and sebum (an oily/waxy matter naturally secreted to lubricate the skin). This acidic property of the mantle appears to be the skin's natural way to fight certain bacteria growth.
Balancing Skin pH
Some cosmetic products advertise claims to balance or adjust the skin's pH in an attempt to skim over the fact that some of these products are quite alkaline (hand soap has a pH of 9-10). Formulating a product so it lies within a common skin pH range would seem reasonable as long as the product is not irritating, but it may not be on one's best interest to attempt to alter a skin's natural pH balance. While it will more than likely not do any permanent skin damage, people prone to dry skin or other skin issues will probably see the most affect with more dry skin or minor compromises in the integrity of the skin's surface. This is not to say all alkaline cosmetic products should be avoided, one should just take account the alkaline level when purchasing a product. It is also important to note that the pH of a product can "drift" over time; the pH of a product on the date of its manufacturing could be quite different from the same product that is on the shelf 90 days later.
pH of Sunless Tanning Solutions
When deciding whether to modify a solution or not, it is important to take into consideration that DHA solution occurs in an equilibrium state with glyceraldehyde. This means the more acidic the solution, the more DHA exists and the less glyceraldehyde is present and vice-versa for a more basic solution. At pH values above 7, undesirable reactions occur that may compromise the integrity of the product, but even when stored, a natural-formulated DHA solution will only drift to maybe a 3-4 pH value. It is suggested to formulate a DHA solution to its natural pH range for both stability and effectiveness, we highly recommend to be more focused about the pH range of an aftercare moisturizer than attempting to alter the pH of a DHA solution.
Some pre-sunless spray products are sold to remove excess skin oils and daily grime when used before a sunless tan. These products are particularly valuable when the client has not properly exfoliated before the session. Some of these products also claim to adjust the skin's pH. However, we believe this to be a relatively minor claim and suggest that a pre-sunless product should be evaluated on its ability to prepare a clean and even tanning surface.