In Search of Better Solvents

Dear Valerie: I’ve noticed Ethoxydiglycol and Dimethyl Isosorbide quite a bit in skincare products. Are they necessary to include or will using propylene or butylene glycol suffice?
—Better Call Solvent

Dear Better:

Ethoxydiglycol and DMI are used either as solvents or penetration enhancers, or both. Most good skin care actives require careful delivery to penetrate the outermost layers of the skin, and these two solvents offer the right polarity to facilitate this penetration. I personally like DMI because it is more effective at dissolution than Ethoxydiglycol and has been shown to be less irritating in application of certain actives, like Benzoyl Peroxide. I’m sure there will be some in the Ethoxydiglycol camp. I don’t like the smell of either of them, although DMI seems less offensive to me.

What is nice about these two over the traditional humectant glycols is their increased polarity and reduced propensity to cause irritation compared to the glycols. They are also less sticky and, therefore, don’t leave that large transition phase from wet to dry on skin or scalp. While they are more costly, I think you will find their benefits outweigh the cost and you can work them into your formulation.

Valerie George is a cosmetic chemist, science communicator, educator, leader, and avid proponent of transparency in the beauty industry. She works on the latest research in hair color and hair care at her company, Simply Formulas, and is the co-host of The Beauty Brains podcast. You can find her on Instagram at @cosmetic_chemist or showcasing her favorite ingredients to small brands and home formulators at simply-ingredients.com. Her email is askvalerie@icloud.com.