Microemulsion serum preservatives
Hi all, new member here but I’ve viewed quite a few posts on preservatives already. Long story short, I’m formulating a microemulsion-based serum for a colleague’s cosmetics startup. The micelles are 30-40 nm, or 80-100 nm depending on the formulation. I’m using a proprietary oil blend (including 2.5% Vitamin E), Polysorbate 80 (P-80) as the surfactant (sometimes PEG400 as a co-surfactant), and water. My concentrates are 60% oil, 30% P-80, and 10% water, but my working concentration will likely be 20% oil, 10-15% P-80, and 65-70% water.
Preservatives are of course the issue. My friend who’s a professor in pharmacology and an expert in dermal drug delivery likes parabens, but she cautions against using them due to negative public perception. Phenoxyethanol seems possible to use, and despite some people saying they’re inactivated by polysorbates, I found several papers showing enhanced anti-microbial activity. Would appreciate any clarification. Germall Plus (Powder) sounds fantastic, but I read that it failed for a few of you? I won’t use a low pH system, so sodium benzoate is out. What else should I consider that will be effective, and not cause a negative reaction (justified or not) from consumers?
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