Monday, October 5, 2009

Modifying lotion recipes - substituting emulsifiers

Let's say you find a recipe online that you like, but you don't have the required emulsifier. You can substitute Polawax, BTMS, or e-wax for the emulsifier, or you could use the HLB system to create your own!

I'm going to use the Hydrating Hemp Hand & Body Lotion recipe from Voyageur as an example(scroll down a bit to see it).

You can substitute BTMS or emulsifying wax at the same amounts if you're using either of these emulsifiers.

Remember, I have no experience with other emulsifiers, so I can't comment on using any of the "-mulse" emulsifiers from places like the Herbarie.

If you want to use the HLB system...

1. Identify the ingredients with an HLB value in your recipe...(in green). Always check the cool down phase to see if there are any silicones or other oils there!

6.5% hemp seed oil - HLB: 7
5.5% sunflower oil - HLB: 7
2.0% avocado oil, golden - HLB: 7
2.5% stearic acid - HLB: 15

2.5% glycerin
5.5% Polawax (quite clearly we're leaving this out!)

74% water

0.5% panthenol
0.5% cromoist
0.5% liquid germall plus
Fragrance at up to 1%, if desired.

2. Find the total of your oil phase - 16.5% of the lotion recipe.

3. Find the percentage of each oil ingredient in the oil phase.

6.5% hemp seed oil - 6.5/16.5 = 0.40
5.5% sunflower oil - 5.5/16.5 = 0.33
2.0% avocado oil, golden - 2.0/16.5 = 0.12
2.5% stearic acid - 2.5/16.5 = 0.15

As an aside, try dividing each percentage of the oil phase by the total oil phase amount. All the numbers in the above oil phase repeat! It's cool! Yep, I'm a math geek!

4. Multiply the percentage of each oil ingredient in the oil phase by the HLB value.

6.5% hemp seed oil - 6.5/16.5 = 0.40 x 7 =2.8
5.5% sunflower oil - 5.5/16.5 = 0.33 x 7 = 2.31
2.0% avocado oil, golden - 2.0/16.5 = 0.12 x 7 = 0.84
2.5% stearic acid - 2.5/16.5 = 0.15 x 15 = 2.25

Our HLB value for this oil phase is 8.2.

Now choose your emulsifier!

We could go with ceteareth-20 and glycol stearate and do the math until it reaches 8.2. But let's try something different!

Or we could try another about lecithin (HLB 4) and behenyl alcohol (HLB 15.5). After much math doing, I found that 37% behenyl alcohol plus 63% lecithin has an HLB value of 8.255. So let's go with that. If we use 4% emulsifier, we'll need 1.48% behenyl alcohol and 2.52% lecithin to emulsify this recipe.

Or we could try PEG 7 olive oil esters (HLB 11) and glyceryl stearate (HLB 3.8) and find we need 60% PEG 7 and 40% glyceryl stearate to reach an HLB of 8.12. So we would use 2.4% PEG 7 and 1.6% glyceryl stearate.

As a note: I have no idea how the above emulsification systems feel as I've chosen them purely by HLB value so please try them out before making huge batches!

You'll note the original recipe contained 5.5% emulsifier, which means at 4% emulsifier using the HLB system, we're missing 1.5% to get the recipe to total 100%! EEK! You could include more water, increase the panthenol and cromoist, or add a few goodies you like. But if you add some oil based goodies - silicones, extracts, and so on - you'll have to evaluate the impact this will have on your emulsification system.

Join me tomorrow for turning lotions into creams!


Anonymous said...

Hi Susan,
Question for you how did you like this recipe?

Susan Barclay-Nichols said...

I liked the original version and I liked my version with ceteareth-20 and glycol distearate. I found the modified version was lighter than the version with Polawax (which felt a bit greasier). I notice Voyageur has changed the recipe now, using avocado oil instead of sunflower oil, so I don't know what the new version feels like (I'd guess it feels heavier thanks to the avocado oil).

m. said...
This comment has been removed by the author.
Susan Barclay-Nichols said...

Hi m! Check out the posts I've written about the HLB system to see how you can figure out the HLB of your oil phase and the HLB of your emulsifiers. I don't understand why it would be suggested to use lecithin in the cool down phase as it can be heated, but it's an even worse idea if it's being used as a co-emulsifier. It needs to be heated to work.