Aqueous Phase – Cosmetic Uses in Emulsion and Water-Based Formulations

What Is the Aqueous Phase?

The aqueous phase is the water-rich part of a cosmetic formulation. In conventional emulsions, it is combined with an oil phase to produce the final emulsion.

Purified water is usually its major component, but the aqueous phase may also contain glycerin, propanediol, glycols, water-soluble polymers, acids, bases, buffers, chelating agents, preservatives and water-soluble active ingredients.

Role of the Aqueous Phase in Formulation

The composition of the aqueous phase has a major influence on the properties of the finished product. Factors such as pH, conductivity, ionic strength and dissolved solids can affect viscosity, emulsification, preservation and ingredient stability.

The order in which ingredients are added can also be important. Some polymers need to be fully hydrated before electrolytes are introduced, while heat-sensitive active ingredients may need to be incorporated during the cooling phase.

Formulation Considerations

Water quality is critical in cosmetic manufacturing. Variations in mineral content, microbial quality and conductivity can contribute to differences between production batches.

The aqueous phase should be evaluated for pH, clarity, viscosity and compatibility before and after incorporation into the complete formulation. An ingredient that performs well in water alone may behave differently once combined with the other components of the finished product.

References

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

European Commission. CosIng – Cosmetic Ingredients Database.

Lachman, L., Lieberman, H. A. and Kanig, J. L. The Theory and Practice of Industrial Pharmacy.