Wednesday, April 27, 2011

HLB system: Substituting things in our oil phase

Let's take one last look at the HLB system for making our own emulsifiers before we return to duplicating products. Remember that if you make a change to any of the oil soluble ingredients you'll need to re-calculate your emulsifier! If you're going from one vegetable oil to another - soy bean oil to sunflower oil, sweet almond to olive oil, and so on - you probably won't have to do a lot of math as most of them have an HLB of 7.  If you change butters, mango butter (HLB 8) or shea butter (HLB 8) to cocoa butter (HLB 6), you'll have to do some math.

32% water
20% aloe vera
3% glycerin
0.5% allantoin
2% hydrolyzed oat protein
2.5% sodium PCA

5% refined shea butter
7.5% soy bean oil
7.5% sesame oil
2% IPM or IPP
3% cetyl alcohol
6% BTMS-50

2% cyclomethicone
2% dimethicone
1% Vitamin E
2% panthenol
0.5% powdered chamomile extract
0.5% liquid Germall Plus
1% fragrance oil (Clementine Cupcake)

I'm going to summarize the steps quickly here. If you want to see the steps again, please click here or hit "older post" at the bottom of the page. 

Our current oil phase makes up 30% of the recipe (count the heated oil phase, as well as the cyclomethicone, dimethicone, and Vitamin E). Divide the percentage of each ingredient by the oil phase to find out the percentage this oil ingredient makes up in the oil phase, then multiply that by the HLB value.  

Shea - HLB 8 - 0.167 x 8 = 1.336
Soybean - HLB 7 - 0.25 x 7 = 1.750
Sesame oil - HLB 7 - 0.25 x 7 = 1.750
IPM - HLB 11.5 - 0.067 x 11.5 = 0.7705
Cetyl alcohol - HLB 15.5 - 0.10 x 15.5 = 1.55
Cyclomethicone - HLB 7.5 - 0.067 x 7.5 = 0.5025
Dimethicone - HLB 5 - 0.067 x 5 = 0.5025
Vitamin E (Tocopherol) - HLB 6 - 0.033 x 6 = 0.198

Our required HLB value for this product will be 8.192

Choose two emulsifiers - let's choose glycol distearate (HLB 1) and ceteareth-20 (HLB 15.2). 

50% glycol distearate (0.50) + 50% cetereath-20 (7.6) = 8.1 

This is close enough for our needs because 49% glycol distearate and 51% cetereath-20 = 8.242, which will be a huge pain to get right because our scales don't generally go to 0.01 grams (unless you're really lucky). So if we're using 5% emulsifier, we'll need 2.5% glycol distearate and 2.5% ceteareth-20. 

Or choose two other emulsifiers! Let's choose sorbitan stearate (HLB 4.7) and PEG-100 stearate (18.8). I eventually figure out that I need 80% sorbitan stearate (5.5) and 20% PEG-100 stearate (3.76) for a total of 8.26, which is close enough to 8.192. If we're using 5% emulsifier, we'll need 4% sorbitan stearate and 1% PEG-100 stearate. 

Let's say we want to make one small change - substituting castor oil castor oil (HLB 14) for soy bean oil (HLB 7). We end up with an HLB of 9.942 (previous HLB 8.192). What a difference! 

If we combine 37% glycol distearate with 63% ceteareth-20 we get an HLB of 9.946. If we're using 5% emulsifier, we'll need to use 1.85% glycol distearate and 3.15% ceteareth-20 just to accommodate the switch from soy bean oil to castor oil. If we're using sorbitan stearate and PEG-100 stearate, we'll have to use 3.15% sorbitan stearate (37%) and 1.85% PEG-100 stearate (63%) to accommodate the changes with 5% emulsifier. 

I want to point that it's a complete fluke that these numbers ended up similar. I chose sorbitan stearate and PEG-100 stearate kind of at random, and I was surprised to see that I needed the inverse for both emulsifiers! 

But what if we want to change some of the oils for others, but keeping the same amounts?

Cocoa butter (HLB 6) instead of shea butter (HLB 8) = 0.167 x 6 = 1.002
Fractionated coconut oil (HLB 5) for the soy bean oil (HLB 7) = 0.25 x 5 = 1.250
C12-15 alkyl benzoate (HLB 13) for the sesame seed oil (HLB 7) = 0.25 x 13 = 3.250
Cetyl esters (HLB 10) for cetyl alcohol (HLB 15.5) = 0.10 x 10 = 1.00
Crodamol STS (aka PPG-3 benzyl ether myristate, silicone replacement, HLB 13.49) to replace the cyclomethicone (HLB 5) and dimethicone (HLB5) = 0.133 x 13.49 = 1.80 (rounded up)
Vitamin E (Tocopherol) - HLB 6 - 0.033 x 6 = 0.198

Our required HLB for this product is 8.50. I'll grant you that it's not that dramatic a change, but if we used the emulsifiers from the last version, we could get some separation. So how much emulsifier will we need?

I eventually figure out that we would need 47% glycol distearate (0.47) and 53% ceteareth-20 (8.056) to reach the required HLB value. This means if we used 5% we'd need 2.35% glycol distearate and 2.65% ceteareth-20. I think that's a pretty significant difference! 

One more post on the HLB system before we get back to learning how to duplicate products tomorrow starting with the Liz Earle Gentle Face Exfoliator! 


ME G said...

Hello Susan, can i ask very stupid question, please? Where are the HLB numbers coming from, are they just given or...?
Thanks, Irina.

Susan Barclay-Nichols said...

Hi Irina! For the oils, they are just given to us. (If you're interested, do a search for how the scientists arrived at these numbers as they interesting.) For the emulsifiers, there's a formula about their solubility that I detail in a post on the topic. Check out the links on the right hand side of the blog to learn more!

ME G said...

Oh thanks Susan, this was bothering me Loooo-ong time!!! I thought these numbers have to be calculated too! And yes numbers next to oils. So it is a bit like with qouontariums, say polyquat- 7, for instance?

Susan Barclay-Nichols said...

Take a look at the post on cationic polymers if you're interested in knowing why they are numbered! Follow your curiosity!

ME G said...

Thank you!