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How much ethanol to preserve formulas and solubilize SA without being drying?
Have a pH 3.8 formula with AHA and BHAs incl citric acid, need to preserve it and solubilize 2% SA better.
Wondering how much ethanol is likely to do the trick, 5 - 10 or 15%? Less is better. The acids will also help with preservation. Will then do USP51 testing once the crystallization issue is solved.
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4 Replies
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Not sure what you’re making, but I imagine for anything skincare-related ethanol would be not ideal. Propylene glycol is a good enough solvent for SA at low %s and works as a co-preservative.
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Why not, 5 - 10% ethanol shouldn’t be drying? Propylene Glycol is a poor sollubilizer no, you’d need 15% or so?
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I got 2% SA into solution with 1.5% propanediol and 1% euxyl pe 9010 (which is the preservative I had to include anyway). I’m sure you could do it with just extra propanediol and avoid alcohol
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Zink said:Why not, 5 - 10% ethanol shouldn’t be drying? Propylene Glycol is a poor sollubilizer no, you’d need 15% or so?
Sorry, I interpreted the question as looking for a preservative and solvent for SA in one. Ethanol as a preservative would have to be higher than I’d want it, not so much for drying but scent and viscosity effects.
If you want to dissolve the SA in a smaller amount of ethanol and add it in it should be fine.
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