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
5.5% Polawax (quite clearly we're leaving this out!)
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 blend...how 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!