Vegetable glycerin is a humectant drawing moisture from the environment. It can also draw moisture from the body and bring it to the upper skin dermis where it can be evaporated a condition known as TEWL (Trans epidermal water loss). To much glycerin can have a drying effect and it should be used in small amounts in formulations to prevent this. Glycerin is skin identical meaning it is already existing within our skin. The trick with glycerin is to find that perfect amount that hydrates but does not pull the moisture from within. It is a clear thick liquid that has a sweet taste and is often used in lip balms in small amounts. Glycerin has a comedogenic factor of 0.