Thursday, April 28, 2011

HLB system: Using different emulsifiers and a formula

I've been using glycol distearate (HLB 1) and ceteareth-20 (HLB 15.2) as my emulsifiers for these HLB posts, but you can use any combination you wish as long as you have a low HLB emlusifier and an high HLB emulsifier in the mix.

Here's what I have in my workshop right now:
  • glycol distearate - HLB 1
  • glycol stearate - HLB 2.9
  • glyceryl stearate - HLB 3.8
  • laureth-4 - HLB 9.7
  • oleth 10 - HLB 12.4
  • polysorbate 80 - 15.0
  • ceteareth-20 - HLB 15.2
  • polysorbate 20 - 16.7
You can create combinations that make the math easier or for a better skin feel. I've chosen glycol distearate and ceteareth-20 because I like the skin feel and I have tons of it in the workshop, but you can go for any combination.

Let's use this as our sample oil phase (from this post). We have a 25% oil phase with 10% soy bean oil (HLB 7),  7.5% cocoa butter (HLB 6), and 7.5%  mango butter (HLB 8) Let's figure out the required HLB value for this lotion.

soy oil - 10/25 = 0.4 x 7 = 2.80
cocoa butter - 7.5/25 = 0.4 x 6 = 1.80
mango butter - 7.5/25 = 0.4 x 8 = 2.40

Our required HLB for this lotion is 7.00.

Let's say we decide to use glycol distearate (HLB 1) and polysorbate 80 (HLB 15). The closest we can get to the required HLB of 7 is 6.87 (57% glycol distearate and 43% polysorbate 80), 6.880 (58% glycol distearate and 42% polysorbate 80) or or 7.10 (55% glycol distearate and 45% polysorbate 80). We can't quite get to 7, so we'll have to fudge it or get even more specific. (See below.)

Or let's say we use glycol stearate (HLB 2.9) and polysorbate 15 (HLB 15). The closest we can get to the required HLB of 7 is 7.014 (which is perfect as far as I'm concerned) with 66% glycol stearate and 34% polysorbate 80. At 4% this would be 2.64% glycolstearate and 1.36% polysorbate 80. At 5% this would be 3.3% glycol stearate and 2.7% polysorbate 80. I think the 5% would be a better choice because we can accomplish that on a a scale that weighs down to 0.1 grams!

Or let's say we decide to use glycol stearate (HLB 2.9) and laureth-4 (HLB 9.7) in a product. The closest we can get to the required HLB is with 40% glyceryl stearate and 60% laureth-4. At 4% I'll need 1.6% glyceryl stearate and 2.4% laureth-4. At 5% I'll need 2% glyceryl stearate and 3% laureth-4.

I work this all out by hand, mainly because I enjoy it. I write down the low HLB emulsifier (usually by HLB number) and the high HLB emulsifier and try 50-50 first. Then I try 60-40 and 40-60 so I can get an idea of where the number might fall. Once I have those three figures, it's easy to figure out where to start and go down by fives or 1 (so 61-39 or 65-35) and so on.

If you are comfortable using a formula for this and want to make it easier, here's one I found from Snowdrift Farms and it works really well for me.

Let's try this out!
required HLB = 7
HLB B (the higher HLB emulsifier, laureth-4) = 9.7
HLB A (the lower HLB emulsifier, glycol stearate) = 2.9

So we need 39.7% of HLB A, glycol stearate. Which means we need 60.3% of the laureth-4. With my math by hand, I came up with 40% glycol stearate and 60% laureth-4, so the formula worked! (And my messy chart isn't as inaccurate as one might suspect!)

Try this with glycol distearate and polysorbate 80 to see if we can get closer to 7.
required HLB 7
HLB B (the higher HLB emulsifier, polysorbate 80) = 15
HLB A (the lower HLB emulsifier, glycol distearate) = 1

And this is where accuracy is important. This means we need 57.1428571% glycol distearate and 42.85741% polysorbate 80. If we do the math here we actually get to 7 (do the math yourself if you wish!) At 57% glycol distearate and 42% polysorbate 80, we managed to get to 6.87, but when we use the formula, we get right to 7.001.

Now this does mean if we're using 5% emulsifier we'll need 2.85714% glycol distearate and 2.14285714% polysorbate 80 in our product, and no one has that kind of scale (at least none of us homecrafter types). So really, we have to round up at some point or we'll never make a product!

I really encourage you to use this formula as it is more accurate and less time consuming than creating a chart!

All right! Let's get back to duplicating knowing what we know now!


Lise said...

I really, really appreciate all the technical stuff on this blog. Great post and so useful (the math isn't daunting, but it's the first time I've run into HLB values, and this explains so much about what does and doesn't work in my lotion experiments). Thank you!

Anonymous said...

I bought a vegetable emulsifying wax (cetearyl alcohol 45-50%, cetearyl glucoside 50-55%). Oils i have available include hemp, avocado, jojoba, olive. It seems that i can't get the HLB of the oils high enough unless i dramatically reduce the water content to less than 70%. A couple of questions: it seems i am heading toward an oil in water emulsion, does this take place after water exceeds 50%? Also, i'm confused about which of the waxes should be included in the oil % - if i use this wax, should the cetearyl alcohol be included as one of the oils? Thanks a mill, Rachel.

Susan Barclay-Nichols said...

HI Rachel. I don't understand your question. You could make a 90% water or a 50% water recipe using the HLB system. It isn't about the water; it's about the oil phase.

Secondly, you have what sounds like an all-in-one emulsifying wax. Ask your supplier what they recommend for usage rates. You don't need the HLB system to use it. Seriously, don't try to figure it out as it will drive you crazy.

Ben said...

Just a question about the oil phase, if the oils equal 100% of the oil phase does the oil phase calculation for 100% exclude the emulsifier? So I've I'm using 5% emulsifier 7.5% of oil 1, 7.5% of oil 2 and 10% of oil 3 is it just the oils that are 100% of the oil phase even though the emulsifier is added to the oil phase or is 100% of the oil phase including the emulsifier percentage you are using? I'm thinking it's without the emulsifier but I just want to be sure.

Susan Barclay-Nichols said...

Hi Ben! As I note in the post, the oil phase consists of the oil soluble ingredients we put into a lotion. As we are trying to figure out how much emulsifier to use, we don't know how much emulsifier is in the product, so it's not part of the oil phase. (As an aside, emulsifiers are never considered part of the oil phase when we are figuring out the HLB system.)