Heating, holding, freezing, and thawing our oils - Lexi asks: It's summer so time to break out the insect repellents. I want to make my own insect repellent lotion based on essential oils (e.g. lavender, eucalyptus, citronella). My product is 8% essential oils. I know you said that we are not supposed to heat our essential oils but I only obtain a stable product if I heat (otherwise the oils "seep out"). Are my essential oils really that delicate that I can't heat and hold and 65C? Thanks for all the information you are sharing on this blog.
Before you make anything with an essential oil, please check the suggested usage rates. 8% of anything seems really high for a leave on product, so please check the usage for each oil and research how to combine them together.
It sounds like your aren't using enough emulsifier as you note the product is unstable. When you add more oils to a product - this includes fragrance and essential oils, as well as extracts - you need to compensate for said oils in the emulsifier. The oil phase of a product includes every oil soluble ingredient in the heated oil phase and the cool down phase.
If you are using Polawax in this recipe, adding 8% essential oils to the product means you need 2% more Polawax in your recipe. 2% might not sound like a lot, but it really is when it comes to emulsifiers. If you're out by 2%, you will likely experience a lotion fail, which is what you're seeing with the oils seeping out.
e-wax. Ritamulse SCG can't be used for more than 25% oils at all. (For other emulsifiers, check the suggested usage rate.)
As a question, are you heating and holding at 65˚C? The suggested temperature is 70˚C to 80˚C.
As for essential oils being delicate - they are. They contain a lot of volatile ingredients that will evaporate when they are heated or poured into a heated product, so we use them at lower levels to avoid said evaporation. You can confirm this for yourself when you're making products. Heat some oil to 70˚C, then add the essential oils to the mix. In another container, put some room temperature oils and add the essential oils to the mix. Notice how much more fragrant the heated oil container is than the room temperature oil. This is because of the volatile ingredients that evaporate on contact with the heat.
Join me tomorrow for more fun formulating with stuff and things!