Propanediol is a chemical that is used to control the viscosity in a formula. That means it can be used to make a formula thicker or thinner. It is considered similar to propylene glycol, but it is different in a few ways. Propanediol has a higher melting point and a lower melting point.
Usually, it is man-made synthetically. But it can be derived from fermented corn sugar. And corn-derived Propanediol uses up to 35% less non- renewable energy than chemically-derived propylene glycol.