W/O Emulsion Stability for Liquid Formulas

Question

I am developing a water-in-oil (W/O) formulation that includes mica and aims for a liquid texture. Currently, I am using Polyglyceryl-6 Polyricinoleate and Polyglyceryl-2 Isostearate as emulsifiers, but the product is experiencing leaking. I would like to know if Polysorbate 20 or PEG-30 Dipolyhydroxystearate would be a better alternative to improve the stability and prevent leaking while maintaining a liquid texture.

MySkinRecipes Expert · Accepted Answer

Improving Your W/O Emulsion Stability

It sounds like you're aiming for a stable, liquid water-in-oil (W/O) emulsion without mica, and are experiencing leaking with your current emulsifier system of Polyglyceryl-6 Polyricinoleate and Polyglyceryl-2 Isostearate.

Between Polysorbate 20 and PEG-30 Dipolyhydroxystearate, PEG-30 Dipolyhydroxystearate is the more appropriate choice for improving your W/O emulsion.

Why PEG-30 Dipolyhydroxystearate is Recommended:

Designed for W/O Emulsions: PEG-30 Dipolyhydroxystearate is a water-in-oil emulsifier (HLB 5.5) known for its good performance in these systems.
Promotes Liquid Formulas: This emulsifier is specifically highlighted for its ability to create liquid formulas, making it suitable for your goal of a non-thick texture, such as in body milk or liquid makeup.
Enhanced Stability: It offers good resistance to acids, alkalis, and electrolytes, which can contribute to overall formula stability.
Formulation Tip: For W/O formulas using PEG-30 Dipolyhydroxystearate, we recommend adding about 1% Magnesium Sulfate to further improve stability and reduce the chance of separation.

Why Polysorbate 20 is Not Ideal:

Polysorbate 20 is primarily a high-HLB solubilizer and an oil-in-water (O/W) emulsifier. While it is soluble in water and glycerin, it is incompletely soluble in oil. Introducing Polysorbate 20 into a W/O system could potentially destabilize your emulsion, as it would encourage the formation of an O/W emulsion, counteracting your desired W/O structure.

Recommendation:

Consider incorporating PEG-30 Dipolyhydroxystearate into your formulation, potentially replacing or adjusting the levels of your current Polyglyceryl-6 Polyricinoleate and Polyglyceryl-2 Isostearate. Remember to also consider adding Magnesium Sulfate for enhanced stability.