In the past I've used ewax to emulsify a 0.3% retinol formula and honestly it has worked OK stability and efficacy wise (we did RT stability testing assaying retinol %), the higher the oil content the better the stability generally speaking.
I'm wondering however if other emulsifiers could be better with regards to:
- Sensorials (more glide)
- Efficacy (better penetration)
- Stability (less degradation)
- Moisturization (e.g. better TEWL reduction).
And not be irritating to the eyes (wonder if some glucoside containing emulsifiers like montanovs could cause eye irritation too easily?).
There was a discussion about the best natural emulsifiers here: https://chemistscorner.com/cosmeticsciencetalk/discussion/5195/brainstorm-the-best-natural-emulsifiers
Montanov L seems like a good pick here as long as eye irritation doesn't become a problem, any other suggestions?