Tuesday, September 29, 2009

Things to think about when creating an emulsification system.

We can, in theory, combine any low HLB and high HLB emulsifiers to create an emulsification system. But there are reasons you might not want to use certain combinations. Perhaps you're avoiding certain emulsifiers because they contain elements of something you don't like. Or you can't get your ingredients reliably or locally. Or you might hate the skin feel. The whole point of coming up with a customized emulsification system is to find something you love and want to use in everything!

I've been working with glycol distearate and ceteareth-20 for a few reasons...

1. I have some at home and I can get it from local suppliers;
2. It's the one LabRat seemed to recommend the most; and
3. It has a nice skin feel.

For instance, it's perfectly fine to use lecithin (HLB: 4) and polysorbate 20 (HLB: 16.7) together, but it might be hard to figure out the HLB for your specific lecithin as its HLB values are listed as 4, 7, and 9! You can use glycol stearate (HLB: 2.9) and polysorbate 80 (HLB: 15) to reach your target HLB number, but you have to consider how you like the skin feel of the end product!

How do you figure out whether you're going to like it or not? Try it. This approach will take some supplies and your time, but it's really the only way to make sure you're a fan of the system you've created. Try it shortly after you've made it, then try it a few days later. If you like it, keep it. If you don't, change it. (I know, I know, this must seem like an irritating answer, but it's really about what you like. No one can tell you what you'll like or what works well for you, so experimentation is really the only way to know!)

When you feel you have chosen an emulsification system you like and want to use for future lotions, try reducing the amount to 3% then 2%. If you've chosen wisely, 2% should work well. We've started out at 4% as it's more likely an emulsion with work at this level, and it gives you a chance to see how you like the skin feel.

The down side of using the HLB system for an emulsion is this...you can't just throw things in and modify a recipe without a little work. Let's say it's winter and I really need an intense body butter with heavier oils. If I'm using emulsifying wax, I'll change the oils, add some silicones, and increase the butter and all I have to do is take the e-wax up a bit, ensuring it is 25% of my oil phase. If you're using the HLB system, you'll have to recalculate your oil phase to find your target HLB number again, then recalculate your emulsifiers.

It is worth it, but you might find yourself spending more time in your workshop, lab, barn, or lair in the beginning.

Join me tomorrow for when lotions go bad!


Ursula said...

Hi, I have only a limited variety of both emulsifiers and surfactants available to me where I live and they are all relatively pricey. while I understand that the best way to work out what I want to use is to try them for myself, thats not really practical for me to try all of them, I wondered if you might have or know where I could find a list of surfactants and emulsifiers with the properties and the feel they give to products that I could use as a starting point to narrow down which I should get to start with to try out myself.

thanks in advance,

Susan Barclay-Nichols said...

Hi Ursula! Have you tried looking in the surfactants section of the blog or looking at the emulsifiers I have listed in the ingredients section of the blog (to the right of the page)?

Ursula said...

Hi, yes I've looked at most of the comparison charts, and they where really helpful thanks, do you know where I could find more information on the skin feel of different emulsifiers?


p.s. I think your blog is amazing and it has been so helpful for my understanding of the science and chemistry of cosmetic making, I'm kind of in awe of the amount of good quality information you have here and your blog is my go to resource when I'm trying to figure something out.