Oils and Water do not mix. This is a basic rule. While making Creams and Lotions, we have both the Water phase as well as oil phase and we use surfactants (or emulsifiers, the two can be used interchangeably)

Surfactants have both water-loving (Hydrophilic) and Oil Loving (Lipophilic) particles which hold both particles well in a mixture.

There is yet another topic which I shall discuss in detail more – Oil in Water Emulsions and Water in Oil Emulsions, which also will help u pick the right surfactant.

For now, let’s dive into HLB

What is HLB (Hydrophilic Lipophilic Balance)

William C. Griffin of the Atlas Paper Company introduced the HLB system in 1949. Understanding the importance of these hydrophilic-lipophilic proportions, Griffin devised a method to calculate HLB values of non-ionic surfactants within a range of 1 – 20.

HLB is a balance between Hydrophilic and Lipophilic molecule of an amphiphilic Molecule (a molecule which is both)

This system is only applicable to non-ionic molecules and applies to PEG derivatives. This doesn’t apply to natural-based emulsifiers/surfactants

How to find which Surfactant/Emulsifier to use using HLB Method

Calculating the HLB Value of Oil Phase

Each Oil has its own HLB Value. However, there is more than 1 oil used in Oil Phase. The required HLB of an oil phase mixture can be calculated by first calculating the per cent of the oil phase each ingredient contributes. This percentage is then multiplied by the required HLB for each of those ingredients and the results are summed.

  1. Calculate the % of each oil in the given oil phase %
  2. Multiply that received % of each oil with its HLB
  3. Add the total of all HLB value of individual oil phase ingredients

Eg.

Oil Phase –