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Emulsifier for an “anhydrous” serum that really is an emulsion
I am formulating face serums made entirely of plant carrier oils, super-critical CO2 extracts and ethanol-water extracts (tinctures). For example:
87.5% Carrier Oils
5% CO2 supercritical extracts
6.5% Ethanol-Water Extracts
0.7% Polyglycerol-3 Beeswax (emulsifier)
0.3% Benzyl Alcohol DHA (preservative)The amount of water varies based on the extract. Let’s say the average overall is 3.3% water and 3.2% ethanol. The ethanol-water extracts should be miscible with oils however they are not.
I decided to add polyglycerol-3 beeswax as an emulsifier because manufacturer states it can be a low HLB emulsifier used between 0.1% - 2%. It does seem to emulsify the formula but I am ready to stability test and challenge test this as a product. I have questions /concerns prior to testing:
1. I heat process polyglycerol-3 beeswax with 1 carrier and add it to the rest of the carriers cold. As soon as I add it to cold oils, it forms agglomerates - clumps or thick ropes. After high-shear mixing they mostly go away but I am not sure how stable the emulsion is? One formula has lasted 6 weeks at room temperature so far.
3. Can anyone suggest a better emulsifier for an oil-based formula that has such little amount of water? Or can anyone suggest a better process to assemble the formula without the emulsifier clumping? Thanks.
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3 Replies
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Polyglyceryl-3 beeswax isn’t a real emulsifier although it has some emulsification properties but an oil gellant and a good stabiliser for w/o emulsions. Although you can keep it as a rheology modifier if you want to thicken up this product you need a proper w/o emulsifier. There are plenty of them, I would say polyglyceryl-4 oleate or sorbitan oleate are easy to find and inexpensive options but there are many others.
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Regarding the process, usually w/o are made by slow addition of water (pretty much by drops) to oil/emulsifier phase under low shear. Can be done via both cold and hot process depending on materials. Cera bellina needs heating obviously but if your emulsifier is liquid usually it’s ok to add without heating. I am more familiar with high internal phase emulsifiers, that also require high shear after emulsification is done (it adds viscosity), but when I started learning how to make w/o emulsions I made one with GMS (not SE the regular one) and polyglyceryl -4 oleate without applying high shear and it looked fine (I observed it for 2 months and it didn’t seep). It looked like soft medicinal ointment.
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If you’re going to heat one phase, you’ll need to heat the other oils when you add it- I assume you’re heating to ~65C? It’s shocking the beeswax and causing it to solidify. You might not have to heat the others as high, or you can slowly add the carrier oils to your hot phase to gradually cool it without shocking. It’d be interesting to compare stability of your current method to any update you make
Acticire is supposed to work for small water additions (INCI: Jojoba Esters (and) Helianthus Annuus (Sunflower) Seed Wax (and) Acacia Decurrens Flower Wax (and) Polyglycerin-3). I’ve only used it in one formula and it was not successful, but that could be due to other factors.
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