First off, a huge thank you to all who provide so much knowledge here. I am not a cosmetic chemist, which will be very obvious momentarily, but a home-crafter and this forum has been a valuable source of information over the past year. I am working on stabilizing a body lotion that uses LotionPro 165 (glyceryl stearate and PEG 100 stearate) with Sepimax Zen (polyacrylate crosspolymer-6). I read a post that said to add it to the oil phase and another that said to add it to the water phase while overhead mixing. To put it simply, I’ll state my questions upfront and then detail what I actually did:
My reason for adding the polymer is due to, as you guessed, stability issues with the lotion that did not have any polymer around the 9-month mark. It started to thin out considerably, which is what I surmise as separation happening. The heat wave here in the West didn’t help either. So I researched that I needed a rheology modifier like xanthan gum or a polymer to stabilize it. I chose Sepimax Zen for its wonderful sensory profile and I already had quite a lot of it from making hand sanitizer.
My formula and process is below:
Note: I do not have an overhead mixer but have rigged my immersion blender with a rheostat for variable speed and attached it to stand for overhead mixing. It can usually go 10 minutes on the lowest setting without overheating.
|Hydrolyzed Rice Protein||A||74.2||2.0%|
|Lavender 40/42 EO||C||40.8||1.1%|
|Lavender 40/42 EO||C||18.6||0.5%|
Sepimax Zen = polyacrylate crosspolymer-6
LotionPro 165 = glyceryl stearate and PEG 100 stearate
AromaFix = PPG-20 Methyl Glucose Ether (helps the fragrance/eo stay longer)PROCEDURE
My initial reaction to the revised formula with the polymer was that it felt wonderful on my skin, ultra-hydrating yet light and fast-absorbing. The most noticeable difference is in the way it “breaks”. It passed my in-house 5-cycle freeze-thaw stability test as well as three weeks in the incubator at 45˚C.
But now I’m wondering if because I added it to the water phase and not the oil phase, that I might have longer-term stability issues. Something that might not creep up until 6-months from now. Is there anything else I'm not considering that I should?
Any advice and feedback would be greatly appreciated!
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