A quick summary of the HLB system…
All emulsifiers have a hydrophilic head (water loving) that is generally composed of a water soluble functional group and a lipophilic tail (oil loving) generally composed of a carbon chain derived from a fatty acid or fatty alcohol.
The head is in red in this diagram, sticking out into the water phase.
The tail is the squiggly bit in the yellow part, which is the oil.
The theory behind HLB is that emulsifiers showing greater solubility in water would be better for oil in water emulsifications; emulsifiers showing great solubility in oil would be better for water in oil emulsifications.
The lower HLB value emulsifiers are better in water in oil as they are more lipophilic or oil loving.
The higher value HLB emulsifiers are more hydrophilic or water loving.
You can see there are general categories listed for where an emulsifier might fall. You a see that over HLB 10 is more water soluble. You can also see that detergents are in the HLB 13 to 15 range.
But they can go lower. Cocamidopropyl betaine – an amphoteric surfactant we use as a secondary surfactant – has an HLB of 10 to 12 and lauryl betaine has an HLB value of 8 to 12, and we know they are mild cleansers. So when you see something in that range, note that they might also be detergents.
Solubilizing agents are HLB value 15 and up, something to note. These include ingredients like polysorbate 20, polysorbate 80, PEG-40 hydrogenated castor oil, Natragem S 140, caprylic/capric triglycerides, and more.
As a note, I see people using caprylyl/capryl glucoside as a foamy, bubbly, lathery™ surfactant when it has an HLB value of around 15, which puts it in the solubilizer category. It would be like using polysorbate 20 or 80 as a huge part of a shampoo or body wash – eeek! They’re all so sticky!
Learn more about the HLB system in the emulsifiers, conditioners & solubilizers section of the site, always found under the “ingredients” tab in the menu.
Learn more about surfactant and solubilizer HLBs in this post – Q&A: Using surfactants in a foamy, bubbly, lathery™️ formula as solubilizers for small amounts of oil
Learn more about the HLB system in this post – HLB system – introduction to the series