Propanediol is a clear, watery liquid, which is widely used in skincare as a humectant, solvent, penetration enhancer and preservative-booster. It’s non-irritating, and we love that propanediol, like many of our other favourites, is a true multitasker. This means less ingredients, which for our sensitive and problem-skinned faces is a must.
We’ve covered humectants in our blog before, but just to re-fresh: humectants are hydrating ingredients that attract and bind water to themselves. In essence, they’re responsible for moisturising skin in a skincare product. Propanediol has excellent hydrating properties and is often paired with glycerin to reduce glycerin’s stickier skin feel.
A solvent is a substance that dissolves a solute, resulting in a solution. In plain English this means that if you stick something into propanediol it will break down. In skincare, this means propanediol can be used as a base for e.g. plant-extracts, which can then be easily incorporated into water-based products.
A penetration enhancer, true to its slightly discomforting name, helps other skincare ingredients penetrate better. This is especially useful when you have actives with a larger molecular size. The presence of propanediol in a product will give it more kick, sort of.
A preservative booster is something which enhances the performance of a regular preservative, sometimes enabling the use of lower amounts of preservatives. A real-life example of this is our Clarifying Treatment, which our chemist Jaana created without any added preservatives by using propanediol along with glycerin (also a preservative booster) and anti-microbials.
Finally, chemically speaking propanediol is a glycol, and the one we use is made from fermentation of glucose, from corn. It’s approved by Ecocert and certified by the Natural Products Association.