Hydrophile-lipophile balance definition

Table 1 summarizes the relation between the hydrophilic-lipophilic balance (HLB) of surfactants and their ability to form concentrated emulsions. Because the continuous phase is that phase in which the surfactant is soluble, it is expected from the definition of HLB [17,18] that surfactants with low HLB values are oil-soluble and can therefore generate w/o concentrated emulsions, while those with high HLB values are water-soluble and can lead to o/w concentrated emulsions. Span 20, whose HLB is 8.6, can generate both w/o and o/w concentrated emulsions. 

---