Rough recipe that should have enough clues

Water phase ~50%
Oil phase ~50%
Water Phase: Water, Sodium Lactate, 5% Lactic Acid.
Oil Phase: 7% Ewax, Tamanu Oil, Hemp Seed oi, Shea Butter, 5% Salicylic Acid, 5% Lipoic acid, Sulfur, Stearic acid, Vitamin E.
Cooldown: Zinc Oxide
The oil phase separated on its own, and when mixed with the water phase under high shear mixing and cooled, it curdled. I poured of a small amount of liquid that had separated from the curdle, and it formed a lotion again (not a stable one but alas).
Just wondering which ingredients are incompatible with each other or just low pH? Almost looked like the addition of lipoic acid caused the salicylic acid to precipitate! Or maybe the acids aren't comp with all of the fats..
Comments
Found this paper: 1 part salicylic acid is soluble in 45 parts olive oil and interestingly only 7 parts castor oil, i.e. castor oils is a much better choice.
http://archderm.jamanetwork.com/article.aspx?articleid=520332
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I have read that Cetearyl Alcohol can be used as a co-emulsifier when incorporated at rates greater than 5%, so you might want to get the two ingredients - Cetearyl Alcohol and Polysorbate - separately, and then add more Cetearyl Alcohol into your formula to get to that 5% threshold, while still continuing to use Polysorbate 60 as you desire.
MakingCosmetics distributes both of these ingredients. There website is:
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IT does stay in when PG is cooled.
Then, once this emulsion forms, add the Salicylic Acid dissolved in 1,3-Propanediol during cool down.
And, 50% Oil phase is crazy high ... you should drop that to 20% max.
See website for details www.desertinbloomcosmeticslab.com
You can search for old threads via the search facility at top, right of the page.
To be more specific re. your question, as the variables in mixed (3 or 4) solvent systems are so wide the best, perhaps only, way to determine salicylic acid solubility is to experiment yourself.
Another thread exhumed (2014)
But with a new twist!
The new section ought to have a new thread but I have made a reasoned response, I think.
It can be a bit confusing sometimes, I don't always see in time that it's old. But you're right! Your answer came in handy for myself aswell (SA solubility finding out by experimenting).