The importance of pH testing on Cosmetic Products
The pH scale ranges from 0 to 14 with the neutral point being 7. Values over 7 denote bases and values under acids. The further the value is away from the neutral point, the stronger the acid or base (the latter is also known as alkaline). Skin surface pH ranges between 4 and 6, which means that it is slightly acidic. This helps the skin surface ward off pathogens that can cause disease. The slightly acidic skin pH also stabilises the skin's barrier function which prevents water loss from the inside and penetration of pollutants or irritants from the outside. Thus, the protective function performed by the skin's acid mantle is weakened by changes in the pH value. Such change can cause skin infections, dehydration, skin irritations and allergies. Skin care products are able to alter the pH of the skin surface. Soaps for example, are bases and increase the normal skin surface pH, which results in a higher risk of damaging barrier function and a reduction in anti-microbial protection. An "in use test" examines a cosmetic product under normal, 'regular use' conditions for a certain period of time by a group of test subjects. The measurement of the pH-level on the skin surface is an important parameter for evaluating the nature of the skin surface in relation to the use of a cosmetic product. Cosmetic products that alter the normal skin surface pH the least are generally considered better for our skin. |
