Potassium hydroxide is commonly known as caustic potash. It is used to fix the pH of a product or as a cleaning agent in soap. In cleansers, it is used for the saponification of oils.

Sapnification is the process of creating fatty acid metal salts from triglycerides and a strong base. During this process, Potassium Hydroxide is used up and is not present in the final product.

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.