Isopentyldiol Good Solvent Hydration Isopentyldiol at a glance Synthetic ingredient that is used as solvent to form cosmetic solutions Can also add hydration to skin thanks to its humectant properties Provides emollience minus a tacky feel Described as an odourless, colourless, water-soluble liquid Isopentyldiol description Isopentyldiol is a synthetic ingredient that is used as solvent to form cosmetic solutions. It can also add hydration to skin thanks to its humectant properties. Suppliers of this ingredient note it provides emollience minus a tacky feel. Isopentyldiol is found in all kinds of beauty products, including facial masks, serums, makeup remover wipes, foundations, and hair care. As a raw material, it is described as an odourless, colourless, water-soluble liquid. In their 2018 assessment, the Cosmetic Ingredient Review Expert Panel surveyed 160 personal care products containing up to 15% isopentyldiol and gave their seal of approval for this ingredient’s safety.