Co-Emulsifiers – Cosmetic Uses in Emulsion Stabilisation

What Are Co-Emulsifiers?

Co-emulsifiers are ingredients used together with a primary emulsifier to improve the stability and physical properties of an emulsion. They can contribute to the formation and strengthening of the interfacial film between the oil and water phases.

Unlike primary emulsifiers, co-emulsifiers are generally not relied upon alone to create a stable emulsion. Their role is to support the emulsification system and improve the final product's texture and stability.

Cosmetic Uses of Co-Emulsifiers

Co-emulsifiers are widely used in creams, lotions and other emulsion-based cosmetic products. Depending on their chemical structure, they can help improve:

• Emulsion stability
• Viscosity and consistency
• Skin feel and spreadability
• Resistance to phase separation
• Overall texture

Common co-emulsifying materials include fatty alcohols, fatty acids, glyceryl stearate and certain waxes.

Formulation Considerations

The choice and concentration of a co-emulsifier depend on the primary emulsifier, oil phase, water phase, target viscosity and desired sensory properties.

Fatty alcohols such as cetyl alcohol, stearyl alcohol and cetearyl alcohol are frequently used in creams and lotions because they can contribute both to emulsion stability and to the structure and consistency of the formulation.

The optimal combination should be determined experimentally, as changing the type or concentration of a co-emulsifier can significantly affect viscosity, stability and sensory characteristics.

References

Barel, A. O., Paye, M. and Maibach, H. I. Handbook of Cosmetic Science and Technology. CRC Press.