Saturday, September 26, 2009

HLB or the hydrophilic-lipophilic balance system

When we're working with emulsification systems like e-wax or BTMS, we don't think of how it's going to emulsify our product. We just add the required amount and poof! - we have lotion. But if we want to create an emulsification system of our own, we need to turn to the HLB system for guidance! (Please click to see LabRat's amazing PDF on this topic, replete with all the HLB values for oil phase ingredients and emulsifiers! Download this and treasure it!)

The hydrophilic-lipophilic balance system (or HLB) was created by William Griffin the 1940s as a way of figuring out which emulsifier would work best with the oil phase of an emulsified product. All emulsifiers have a hydrophilic head (water loving) that is generally composed of a water soluble functional group and a lipophilic tail (oil loving) generally composed of a fatty acid or fatty alcohol.

The theory behind HLB is that emulsifiers showing greater solubility in water would be better for oil in water emulsifications; emulsifiers showing great solubility in oil would be better for water in oil emulsifications. The lower HLB valued emulsifiers are better in water in oil as they are more lipophilic; the higher valued HLB emulsifiers are more hydrophilic. (Solubility of a molecule generally increases with temperature, hence the reason for heating and holding our lotion ingredients. And most emulsifiers we use are in a pellet or flake form, so heating is the only way to incorporate it into a liquid environment!)

The HLB value of an emulsifier is determined by the hydrophilic portion of the surfactant. The equation is as follows - HLB = % hydrophilic portion by weight of the molecule divided by 5. (We don't need to know this to use the HLB system, but I'm the kind of girl who has to know everything, so I thought I'd include it for like minded people!) So the higher the number, the higher the portion of the molecule is hydrophilic, and the more water soluble it will be.

Take a look at this polysorbate 80 molecule (HLB 15). Based on this number, we should expect this is an emulsifier that would be better suited for oil in water emulsifications because it has such a high HLB number. (And from experience, we know poly 80 is well suited for adding oil to watery things like toners or facial cleansers - not a lot of oil, but enough that we want it not to float on top of the product!) We don't see any fatty acids or alcohols on this chain, so it's going to be a hydrophilic emulsifier with a high HLB value.

This is sorbitan stearate (HLB 4.7). Based on this number we can predict this molecule would be better suited for oil soluble applications, like a water in oil lotion.

You will never use one emulsifier alone for a lotion - you might for bubble baths, body washes, perfumes, and so on, but for a lotion, you need a system. We want to combine a low HLB emulsifier (the one that loves oil more) and a high HLB emulsifier (one that loves water more) at a level that will match the HLB of our oil phase. And we'll want to add enough of these emulsifiers to ensure we get proper, stable emulsification of our product. (I've seen it suggested that you start at 2% and at 4% emulsifiers in your lotions. I'm going to suggest 4% for now to ensure we have enough in the lotion to be successful.)

So how can use we the HLB system to create awesome emulsification systems? Join me tomorrow for a sample recipe!


Esmée said...

Now off reading the PDF!

ahsan said...

nice explanation..

i know what is HLB basicly,, thanx a lot,,

kontakt said...

This was very interesting reading! I'll get back to it when I dare try lotion making. It has seemed so complicated, with exact temperatures and I don't know what. This is a start to maybe actually understand parts of all that weird stuff. You make it sound like there actually is some kind of science behind the craft.

Susan Barclay-Nichols said...

Hi kontakt. There's some serious science behind lotion making (and, indeed, all bath & body stuff), and adding stuff in the right order at the right temperature is part of the process. The temperatures are exact because some things are heat sensitive - the silicones, preservative, fragrances, panthenol, cationic polymers, and so on - and the heat is important part of emulsification.

For emulsification we use the HLB system to help us create the chemical system required to make an awesome lotion. And the mixing brings it all together (the mechanical part of the emulsification).

I encourage you to try lotion making! I find people can get intimidated by it at times, worrying about the temperatures and inclusion of ingredients and emulsification and everything else. I made lotions with my craft group last week and they really enjoyed it! They weren't scared - they were excited - and I think part of that is that they didn't know it could be scary! (I did the same thing with zippered pouches in sewing group. I didn't tell them it was hard until they'd finished!) Pick a lotion that looks interesting and try it. Then go back and analyze it after you've created your amazingly cool lotion!

kontakt said...

I've been longing for a more - not necessarily scientific in its strictest sense, but more methodical approach. Most people who make their own lotions and shampoos don't know why some things work and others not. So I am very happy I found your blog (and the Dish, but it was your blog that pointed me there).

Your approach to your class and lotions reminds me of my favourite math teacher's approach to derivatives - a good one. I have plenty of other stuff to make, so I think the lotions will have to wait for a while. But I'll get back to them and the HLB system in time. Thanks again!

Still learning said...

Thank you so much for posting this information. I have started researching how to make hair care products and prefer to make everything from the ground up. I was having such a tough time understanding HLD until now. Right now I'm working on making a hair conditioner. Wish me luck.

Anonymous said...

Hi Susan--I am glad to find your blog. I gain lot of info. from it. I am a beginner of learning how to make lotion stuff. I do not know how to start but I have learned myself with all HLB info. and calculate. But when you mentioned about the right heat/temperature, and put stuff in the right order, I am a bit hesitate now. Can you kindly talk more about it. I feel sad I couldnt get the chance to join your group coz I am in Boston, USA. again, thank you for sharing info.

Susan Barclay-Nichols said...

Hi Anonymous. I'm not really sure what information you are seeking - can you be a bit more clear? It sounds like what you want is already on the blog somewhere - scroll down to labels and click on HLB (or click here for now) or click on lotions or look at something like the basic lotion making skills. It's all there on the right hand side of the blog - I might not be super organized, but I do my best!

It sounds like you're new to this, so my suggestion is to stop thinking about the HLB stuff for now and just start with the basic lotion making skills. Check out my newbie Tuesday series that I started a few weeks ago or the creating products series I just wrote. Essentially, go to the latest post on my blog and start there!

m. said...

Hi Susan,
I assume, EOs have their HLB value as well. Have you come across such list? I can't find any info on the internet... :(

Susan Barclay-Nichols said...

Hi m. They might, but I've never seen any reference to us having to worry about it when we're formulating as we aren't using so many EOs in a product that it'll have a profound effect on our lotions. You can assume they are around 7 as most natural oils are, if that helps.

Sorry I couldn't get you more information!