pH is a value that indicates how acid or alkaline an aquaous blend is, by measuring the concentration of hydrogen ions in a solution. The higher the concentration of these hydrogen ions, the lower the pH is and consequently, the lower the concentration of the hydrogen ions, the higher the pH is. You will need to check the pH of any formulation that contains water, such as toners, emulsions, shampoos, body washes and more. pH control is very important in a formulation. Not only does the pH of a product need to be compatible with the formulation and its purpose but it also needs to work with the skin’s physiology and the preservation system of the formula. Particularly in natural and organic cosmetics, where you work with hydrosols, plant extracts and naturally derived preservatives, the pH of the system has a large impact on the stability and efficacy of the ingredients and the overall product itself.