The Ordinary Glycolic Acid 7% Toning Solution

Glycolic Acid is an alpha hydroxy acid that exfoliates the skin. 
This 7% toning solution offers mild exfoliation for improved skin radiance and visible clahis pH of this formula is approximately 3.6. Glycolic Acid has a pKa of 3.6 and pKa is the most important aspect to consider in formulating with acids. pKa implies acid availability. When pKa is close to pH, there is an ideal balance between salt and acidity, maximizing effectiveness of the acid and reducing irritation. Higher pH numbers in such a case would increase salt which counter-intuitively would make the formula even more irritating than if the formula was more acidic.