Acid Average Exfoliant No known benefits Acid description Acids are anything with a pH lower than 7 is considered acidic; above 7 is considered alkaline. Water has a pH of 7. Skin has an average pH of 5.5 In skin care acids mostly function as exfoliants. Exfoliants, like alpha hydroxy acids and beta hydroxy acid, work to slough off dead skin cells from skin’s surface layers to reveal healthier skin. Related ingredients: Alpha Hydroxy Acid Beta Hydroxy Acid