|What is it?||Propanediol is a humectant and solvent derived from corn sugar. It is a good natural alternative to propylene glycol.|
|Appearance||Semi-viscous clear liquid|
|Usage rate||1–20%, though I find it can feel draggy beyond 3%—this does depend on the formulation, though!|
|Texture||In products it tends to be smooth, but too much can be draggy|
|Scent||Nothing very noticeable, slightly sweet|
|Why do we use it in formulations?||It’s a fantastic non-sticky humectant. I’ll often include it in products that I want to be super hydrating (facial lotions, winter products, etc.). I frequently choose it for inclusion in more watery products (things like facial mists, gels, and micellar waters) where a tacky skin-feel would be really noticeable, especially since it can help reduce the stickiness of glycerin.
It helps add clarity and boosts both viscosity and flash-foam in surfactant products. It also increases the feeling of cleanliness on rinse-off.
|Do you need it?||No, but it’s inexpensive and versatile, so if somewhere you’re shopping will sell you a small amount I’d grab a bottle as part of a larger order.|
|Strengths||It’s a great non-sticky humectant that serves many other purposes (see “why do we use it in recipes?”).|
|Weaknesses||Can be harder to find than other humectants.|
|Alternatives & Substitutions||Vegetable glycerin is a decent alternative, though watch that you don’t include so much in the recipe that it starts to feel sticky. Propylene glycol would be a great alternative as they are very similar.|
|How to Work with It||Include it in your heated water phase or cold-process it if the recipe does not require heating.|
|Storage & Shelf Life||Stored somewhere cool, dark, and dry, Propanediol should last about a year once opened.|
|Tips, Tricks, and Quirks||Propanediol can boost preservative performance!|
|Recommended starter amount||30mL (1fl oz)|
|Where to Buy it||Buy it from an online DIY ingredient supplier or Amazon.|