Moisturizing (humectant),Fragrance,Solvent,Viscosity controlling
Botanical, Petroleum, Synthetic
Butylene glycol is a glycol molecule consisting of a straight chain of four carbons with two hydroxyl (-OH) groups attached.
This chemistry is important for two reasons: first, the two hydroxyl groups allow this ingredient to function as a humectant, and second, the straight chain of carbons permits this ingredient to work as an excellent solvent.
The humectancy of butylene glycol, owed to its two hydroxyl groups, is quite considerable. Although it is not as powerful of a humectant as glycerin, which contains three hydroxyl groups, it is the second-best option. This behavior functions based on the hydroxyl groups being attracted to water.
Therefore, when butylene glycol is applied to the skin through a lotion, cream, or serum, it draws moisture to the skin from the environment or from deeper layers of the skin.
In addition to working as a humectant, butylene glycol can also serve as an excellent solvent. Due to its water-loving nature and its oil-loving carbon backbone, it can help dissolve both water-based and oil-based ingredients that normally would not be compatible with each other.
Finally, this clear, colorless liquid can also control viscosity, in that it lowers the viscosity of products when it is added.