Using Polysorbate 20 (Tween 20) as an Emulsifier

Polysorbate 20 is a common non-ionic surfactant used in cosmetic formulations, often functioning as a solubilizer or an oil-in-water (O/W) emulsifier.

• Can it be used alone?
  While Polysorbate 20 has emulsifying properties and can be used to solubilize small amounts of oil into water or create simple O/W emulsions, using it as the sole emulsifier might not provide sufficient stability for all formulations, especially those with higher oil content or complex ingredient mixes. For robust and stable emulsions, it is often recommended to use a blend of emulsifiers with different properties (e.g., combining a high HLB emulsifier like Polysorbate 20 with a low HLB emulsifier).

• How to determine the percentage?
  There is no simple formula to calculate the exact percentage of Polysorbate 20 needed based solely on the oil and water ratio. The required amount (within the typical usage range of 1-20%) depends on several factors, including:

  • The specific type and amount of oil(s) being emulsified.
  • The desired viscosity and stability of the final product.
  • The presence of other ingredients in the formulation.
    Formulators typically determine the optimal percentage through testing and experimentation, starting within the recommended usage range and adjusting as needed to achieve the desired result and stability.

• Which phase to add it to (O/W vs. W/O)?
  Polysorbate 20 is a high HLB emulsifier, making it suitable for creating oil-in-water (O/W) emulsions (where oil droplets are dispersed in a continuous water phase). For O/W emulsions, Polysorbate 20 is typically added to the water phase before combining it with the oil phase. It is not suitable as the primary emulsifier for water-in-oil (W/O) emulsions (where water droplets are dispersed in a continuous oil phase), which typically require low HLB emulsifiers added to the oil phase. Although it can dissolve in oil, its solubility is incomplete, reinforcing its primary use in the water phase for O/W systems or as a co-emulsifier.