The HLB system provides formulators with a practical way to compare the hydrophilic and lipophilic character of surfactants.

In conventional formulation work, emulsifiers with lower HLB values are generally associated with more lipophilic systems, while higher HLB values indicate greater hydrophilic character.

HLB can be useful when selecting emulsifiers for oil-in-water and water-in-oil systems.

Required HLB

Some oils and oil blends are assigned a "required HLB" value. This can be used as a starting point when selecting an emulsifier or combination of emulsifiers.

A blend of two emulsifiers can be designed to achieve an intermediate HLB value.

Limitations

HLB should not be treated as a complete prediction of emulsion stability. Molecular structure, phase composition, emulsifier concentration, processing conditions, temperature and co-emulsifiers can all change the behavior of an emulsion.

Experimental formulation and stability testing remain essential.

References

Griffin, W. C. "Classification of Surface-Active Agents by HLB." Journal of the Society of Cosmetic Chemists.

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