The world of cosmetics is too broad for a general answer. The necessary testing is going to depend on the product and the market in which it exists. I've seen products pass the standard tests, then fail in the real world because the standard tests…
Also, this effect would likely be pH dependent, where it would be less significant below the pKa of the potassium stearate (i.e., where it becomes neutral).
This sounds like it could be either a surface tension issue, a non-Newtonian viscosity effect at low shear, or both. If you can't prevent the bubbles in the first place, have you considered post-processing steps to remove the bubbles?
I would expand on what @Perry said by adding that it would be helpful to analyze the oily layer, perhaps by FTIR or a chromatography technique, and compare it to your raw materials.
@Perry, excellent point!
@jmbenavi, it would be helpful to know more about your observed issue to better recommend possible emulsifiers.
1. Is your goal a macroemulsion or a microemulsion?
2. What mixing process are you using to prepare the emul…
Let me know if you'd like some assistance in your investigation. I did surfactant formulation and rheology modification work during my PhD. Feel free to message me directly.
Let me know if you'd like some assistance in your investigation. I work with one of the largest scientific and engineering consulting firms in the US. We do a significant amount of R&D and failure analysis support. Feel free to message me dir…