The Importance of HLB

The Importance of HLB

Hydrophilic-Lipophilic Balance (HLB) of surfactants determines the outcome of the mixture of water-surfactant-oil in  a ternary phase diagram.5 Point “P” of the phase diagram (below) represents 65% water, 25% oil and 10% surfactant. Physical characteristics of “P” will vary depending on the HLB of emulsifiers and the nature of the oil phase. Most of the emulsions are located around this area of the phase diagram. Increasing surfactants/emulsifiers does not necessarily increase the stability of emulsions. HLB of emulsifiers may not  appear to play a significant rule in a complex formula, but its basic understanding would help to select optimum emulsifiers. 

The ternary phase diagram was mainly originated from research works on soap technology. 6

Formation of liquid crystalline neat (lamellar) phase is very important for the stability of emulsions. After applying creams/lotions almost as high as 85% of water evaporates leaving a surface film composed of non-volatile parts. Emulsifiers greatly determine the degree of continuous residual film on the skin surface. For a basic formula, the combination of surfactants that forms the larger area of isotropic oily phase in a phase diagram will also provide more continuous surface film.

The formation of this continuous surface film is very crucial for the efficacy of physical sun filter based SPF products, makeup products, moisturizing creams, etc.

- See more at: http://www.happi.com/contents/view_features/2008-02-29/the-physical-chemistry-of-cosmetic-formulatio/#sthash.eGmUdU6U.dpuf