## Sunday, November 10, 2013

### Weekend Wonderings: How do self-emulsifying emulsifiers work within the HLB system?

HOW DO SELF-EMULSIFYING EMULSIFIERS WORK IN THE HLB SYSTEM?
In the same Weekend Wondering post, kiev asks: As I am new to lotion making and have done some of the no no's you have listed. I am trying to understand the HLB system and that has prompted a question regarding Ewax or any self emulsifying system. I am currently using Ewax - don't know enough to try to formulate my own emulsifiers yet. I do have an HLB calc and I run my recipes through it just to see the HLB number and to try and start making a correlation between the number and the end product - my emulsifier is ewax which I use as recommended at 25% of oil phase (so in essence I am not really using the calculator for that purpose). Anyway my ewax is listed at 15 HLB from my vendor. My oil phase combinations have been everything from 8 to 11. When I get to the point of trying my own systems I use 2 emulsifiers both high and low HLB to match the HLB of my oil phase - so how is a self-emulsifying product with a HLB value of 15 working for all my creams regardless of the HLB number? I suppose this is more a question of curiosity, but it does make me wonder why in a self made emulsification system you match the oil phase but don't have to with an self-emulsifying system.

This is a fabulous question! The short answer is that we don't worry about the HLB system with a self emulsifying system. Why? Because the beauty of buying something like Polawax or e-wax or Ritamulse SCG is that we don't have to do the calculations and risk possibly getting it wrong. (I realize this answer sounds a bit like me saying don't worry about it, but that's really the answer.) We don't need to do the math for those things because the math has been done for us. And we know that these ingredients work because we've seen them work for years in all kinds of different situations. For instance, we can make a lotion with Polawax with an HLB value of 7 and another one at 11 and still make a great, emulsified lotion, so we know that the HLB value of our lotion doesn't matter when using this emulsifier.

There are emulsifiers that can't handle certain ingredients, which can give us an idea of its HLB value. For instance, Sucragel AOF can't handle non-vegetable or non-seed oils or butters, which gives us an idea that it'll have an HLB value of 6 to 8-ish. And we know that certain emulsifiers can only handle so much oil regardless of how much we use - like Ritamulse SCG - so we have to be aware of the restrictions that come with those emulsifiers.

I know I've seen emulsifiers that have an INCI of something like polysorbate 80 and cetearyl alcohol, something with an HLB value of 15 and something that isn't an emulsifier respectively. Honestly, I have no idea how something like this will work.

Are you sure what you have from your vendor is a self-emulsifying emulsifier? I ask because there are a few vendors who call things self-emulsifying that aren't, things like glycerol monostearate or cetyl alcohol, things that either don't emulsify at all or aren't emulsifiers without a partner in crime.

Related posts:
Is glyceryl stearate an all-in-one emulsifier? (Short answer: No.)
Check what you've got - emulsifiers!

#### 1 comment:

Natalie Jane said...

Hi there! A million thank yous!! Your blog is simply amazing! I have no chemistry background and you have helped me understand so much. 
Ok my question - I have been formulating, my creams using the Emulsifying wax natural from Aromantic UK, I am happy with the results but have come to realize my unhealthy dependency on it! Its expensive and hard for me to source. I must know this formula! (Or similar) I took their INCI, bought those ingredients and try to get the proportion right…It is stated it consists of Glyceryl monostearate and Cetyl alcohol Or the equivalent is - Base emulsifier (Aromantic) with cetyl alcohol.
Although their base emulsifier has an Inci of : Glycerol Monostearate SE )
Am I missing something? Is it actually Glycerol Monostearate SE that I need? They have different HLBs so I’m wondering if I have the wrong type… What is SE? and does it make a difference?
As you pointed out this is not a complete emulsification system. Having tried their mix of Cetyl alcohol and glyceryl monostearate. in many combinations, to my own shame, I can confirm, this doesn’t work! My extremely limited knowledge of chemistry is frustrating but I suspect there is a hidden ingredient in Aromantics Emulsifying wax natural.

My ears pricked up when I read your post “substitutions-reading-inci-names” You spoke about Ritamulse (INCI: Glyceryl Stearate (and) Cetearyl Alcohol (and) Sodium Stearoyl Lactylate),
I think this is the closest thing to what I am trying to make! I want to create a” self emulsifying system” given that my formulas are simple with vegetable oil with cetyl alcohol, I usually end up with a required HLB of 7-8… Assuming then that I need a high hlb and a low hlb emulsifier- would I be on the right track with Sodium Stearoyl Lactylate [HLB = 8.3 ± 1] for the high and Glyceryl Stearate [HLB = 3.8 ± 1] for the low?

Many thanks and so sorry for my long post.
Regards, Natalie