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High vs Low HLB Emulsifiers - Water in Oil Emulsions vs Oil in Water Emulsions (5/25 Exclusive)

Disclaimer; **Before we get to into this post. I do want to mention something VERY important. Not every emulsifier has an HLB. There are some emulsifiers like Ritamulse SCG/Ecomulse (INCI; Glyceryl Stearate & Cetearyl Alcohol & Sodium Stearoyl Lactylate) that do not have an HLB and do not use the HLB system. So it is somewhat of an outdated system and really is not necessary to know in order to formulate stable formulas. Either way, it’s still something we see all the time and is important to know a little about if you are a formulator.  


What is HLB?


HLB is an initialism for Hydrophilic-Lipophilic Balance


  • It’s a system that uses numbers to describe how much an emulsifier prefers water or oil. 

  • An emulsifier or solubilizer is assigned an HLB number, but not all emulsifiers and solubilizers have an HLB

  • The chart goes from 1-20

  • HLB of 20 is water loving

  • HLB of 2 is oil loving

  • HLB of 7 is balanced

  • Anything below 9 is considered to have a low HLB (lipophilic/oil-loving/non-polar)

  • Anything above 11 is considered high HLB (hydrophilic/water-loving/polar)

  • Anything between 9 - 11 is intermediate


*Hydrophobic (water hating) or Lipophilic (oil loving) 

*Hydrophilic (water loving) or lipophopic (oil hating)


What is the purpose of HLB when formulating?

The HLB of an ingredient helps us choose which emulsifier is best for our formula.


  • Low HLB emulsifiers are used to make water in oil(w/o) emulsions

  • High HLB emulsifiers are used to make oil in water(o/w) emulsions


O/W Emulsion vs W/O Emulsion


  • Oil in Water Emulsions have oil in the internal phase and water in the external phase. Oil is being mixed into water.

  • Water in Oil Emulsions have water as the internal phase and oil as the external phase. Water is being mixed into oil. 


The types of emulsions most of us are familiar with are the Oil in Water Emulsions. These are the moisturizer, lotion, & cream formulas I’ve shared.


O/W Emulsions 

Since I’ve talked in-depth about Oil in Water emulsions already, I will just direct you there. If you want to learn more about O/W emulsions and the types of emulsifiers that are used and how to make an O/W emulsion, then watch my emulsions for beginners series. You will learn everything you need to know in order to make your own O/W emulsion. 



W/O Emulsions

  • Water as the internal phase and oil as the external phase

  • They are harder to make

  • Sunscreens in the US are typically Water in Oil  Emulsions and many Makeup products are W/O Emulsions.

  • Just because you have more oil in the formula, that doesn’t make it a W/O Emulsion. What makes an Emulsion W/O is the Emulsifier you use and it’s HLB.



Examples of Low HLB Emulsifiers



*If you aren’t sure what ingredients are low HLB emulsifiers, just go on to any suppliers website and type in “low HLB emulsifiers” in the search bar and some should pop up. Or when you are looking at an emulsifier look for the HLB and if it is a low HLB emulsifier it will have an HLB between 3-6. High HLB emulsifiers have a pH between 7-19



W/O Emulsion Formulating Tips

  • Slowly pour the Water phase into the Oil phase while mixing when making W/O Emulsions. Make sure the water does not pool up to the surface.

  • It’s recommended to homogenize your W/O emulsion for better stability.

  • Adding salt (sodium chloride or magnesium sulfate) to your water phase can help stabilize the W/O emulsion. Trial and error will tell you which is best for your formula.

  • Adding in a glycol (Glycerin, Propylene Glycol, etc.) can help with stability.

  • Adding in both a glycol and a salt could cause instability.

  • You can add in oil thickeners like waxes or oil soluble polymers to thicken/stabilize the emulsion.

  • Always use a preservative! Even if your formula mainly consists of Oil soluble ingredients.

  • Since the formula will consist of mainly oil soluble ingredients be sure to mainly use lighter feeling oily ingredients like emollient esters (i.e. caprylic caprylic triglyceride) as opposed to vegetable oils, as those can be a bit heavy, but if that is the vibe you are going for, then go for it!

  • Use a liquid Low HLB Emulsifier if you need to keep the viscosity thin.

  • Use a Solid Low HLB Emulsifier if you want to increase the viscosity.

  • Do not need to worry about checking and adjusting the pH.

  • If you use butters, keep in mind this can impact the viscosity in different climates which can cause instability. So don’t use butters to thicken. 


I have far less experience with W/O emulsions, but I do currently have some formulas I’ve shared in the past that are W/O emulsions. 



Sources



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