Friday, February 8, 2013

Question: How to use lecithin as the emulsifier in your lotions?

I've been asked this question a lot over the last two weeks and the answer is simple: Lecithin can't be used as the sole emulsifier in an oil in water lotion like product. Don't get me wrong - I love lecithin as an emollient and as a water absorber in a few of my mostly oil based products - but it isn't a full emulsifier on its own for a lotion. The short answer is this: If you want to use lecithin as an emulsifier in your products, you have to create your own emulsifier using the HLB system or hydrophilic-lipophilic system. 

I really encourage you to click on this post (shorter, summary) or this one (longer, introduction to a series) to see what the HLB is all about before reading further...It's okay, I can wait. 

How to do this? You would get the HLB value for your lecithin - 4, 7, or 9.7 (ask your supplier) - and combine it with an emulsifier that works out well mathematically. If you have an HLB value of 4, you would choose something much higher, say polysorbate 80 with an HLB value of 15, to combine with it. If you have an HLB value of 9.7, you'd choose something with a much lower number, like glycol distearate with an HLB value of 1. You'd figure out the HLB value of your oil phase - all the things that could be considered oil soluble in your product, such as your oils, butters, fatty acids, fatty alcohols, silicones, etc. - and then calculate how much of each emulsifier you'll need.

Here's a post on how to work on the figures for the HLB system. And click here to see the list of the emulsifiers and their values (scroll down to page 10).

And that's the tricky part of working with the HLB system. It's hard to know how much of each emulsifier to use. Some people start with 2% total emulsifier, others 4%, and still others 6%. It takes time to create a good emulsification system with the HLB system, and even then you might not like the skin feel. Beginners who have never made lotion should not start out with the HLB system - you don't know how a successful lotion should look or feel, so how will you know that you've created something successful?

If you're new to making lotions, please go buy an all in one emulsification system like Polawax, Incroquat BTMS-50, Ritamulse SCG, Ritamulse BTMS-225, and so on. Please don't start by creating your own emulsifiers! And please don't start off by making your own recipes! Use something tried and true that works well. (Click here for a post on that topic!)

Related posts:
Emulsifying systems - e-wax, Polawax, and Incroquat BTMS-50
Ritamulse SCG
Ritamulse BTMS-225

10 comments:

melian1 said...

there is more to which lecithin you use than just its hlb, too. here is a comparison of soy and egg lecithin properties: http://link.springer.com/article/10.1007%2FBF02568014?LI=true and http://uqu.edu.sa/files2/tiny_mce/plugins/filemanager/files/4281709/84607_42.pdf

and here is info on just the soy: http://naldc.nal.usda.gov/download/26685/PDF

Anonymous said...

Susan,

Please look at the page I created that explains a better way to find the percentages for the emulsifiers when using the HLB system.

http://mathandgranola.blogspot.com/2013/02/easier-hlb.html

Since you work with youths, I think it is important for them to learn how some of the concepts they are learning about in school mathematics is related to more advanced mathematics.

I think this because when I took some material engineering courses, I was really surprised by how many of the students were really stumped by what I thought was pretty straight forward mathematics. It kind of scares me knowing that many, many engineers find math really challenging...and they're not even writing proofs or anything like that.

Alexis

Susan Barclay-Nichols said...

Hi Alexis! Great post. Have you visited my blog often? I ask because I get the feeling you aren't familiar with my writing style or way of sharing information. Did you see the post with the formula for figuring out the HLB? It is a much easier way if figuring it all out, but I didn't start there for fear if scaring off the self-described math-o-phones. I try to explain everything I'm doing in a few different ways to reduce math anxiety. Some people get frazzled when they see percentages, others can handle algebra, and still others see calculus and think "Bring it on!" I try to cater to all those interest levels, and if you read the series on the HLB system, I think I managed to do that. It is all about creating a safe space for someone to feel comfortable to let that anxiety go, to lose that fear of failure, so we can work together to learn something new.

As for the youth in my group, we have a few who have taken university calculus - including my husband - and we do a lot of talking about math and science. We had a rousing discussion a few weeks ago about physics while playing board games, and I have a few of them helping me with my physics project. I showed them how to figure out the circumference of the rings we used for dream catchers and how on use that information to cut out enough suede cord to make an awesome project! Heck, we even talk about the Pythagorean method of walking and we do asymptotic high fives. And you know I try to tie everything back to chemistry! I think my husband and I do a very good job of integrating math and science into our every day activities and projects with our youth. (I also work to get them to use English properly as that can be such a challenge at times!)

I'm glad that you believe in those teachable moments, as evidenced by your newly minted blog. I look forward to seeing what you'll write next!

Alexis said...

Thank you, though I will not be able to post any where near the volume you do. My blog will probably be really boring in comparison to yours. I've read your blog off and on for some time now. Probably more than a year but I don't remember exactly.

I figured you probably did mix a great deal of math and English with the science, but I figured it was worth mentioning anyway!

I wrote the post not to criticize what anyone had written but because I find that method saves me time and I couldn't write about it in less than 4,096 characters, which is the maximum amount of characters that can be posted in a comment on your blog. Though I did try...

I too know how people feel about mathematics. I'm close to the end of my graduate studies for math ed, but education was not my undergraduate degree. It's been tough, not quite so much because of the math but more because of the attitudes of professors and students. How to teach mathematics is very controversial in the U.S., and of course the way I was taught in my youth was the wrong way to learn mathematics or so I'm told. @_@ One of my professors likened the way I was taught to a glorified special ed. I have a mentally disabled sibling. Bet you can imagine what I think of that prof.

Anonymous said...

Hi Susan- Can you post some of your recipes that use lecithin? I emailed you a few days ago about pomade. But I would really like to see the recipes for the low water products using lecithin.

Cindy

Anonymous said...

Hey!

After years fighting with my skin, I have finally found balance with all natural and/or DIY cosmetics. Your site has been amazing and most helpful for me, thank you! :) Though I do have a major in physical chemistry, DIY skin care with emulsifiers is new to me and just started exploring about a month ago.

I was wondering why some say it is duable to use (lyso)lecithin solely? (e.g. here http://myhomemadebeauty.com/2010/09/01/lecithin-benefits-for-skin/ )

Are the differencies in stability, feel, or the quantity of lecithin, perhaps? The lysolecithin I have in hand has an HBL value of 4-6, according to the manufacturer here in Finland, nothing more specific. I made some calculations where I would use Polysorbate-80 as the other emulsifier, but am not sure about the recipe. If I were to make O/W: 20/80 or 50/50, do you have any suggestions or formulas at hand that contain both lecithin and polysorbate-80?

Thanks again,

S.N.

Susan Barclay-Nichols said...

Hi SN! Lecithin on its own isn't an emulsifier. It needs to be combined with another emulsifier - polysorbate 80 is a good choice - using the HLB system of creating emulsifiers. Take a look at those posts - it's not hard to grasp, especially for a chemist!

Balaji Apb said...
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stella said...

I need to create a scrub similar to J R Watkins's Body scrub. Their ingredients are sugar, shea butter, coconut oil, sunflower oil, fragrance, lecithin, and vitamin E. My question is, is the lecithin really necessary in this formulation? They list is as an emulsifier, but what is it emulsifying? There is no water in it.

Susan Barclay-Nichols said...

If you add an emulsifier, your product will rinse more cleanly. Do a quick search for emulsified scrubs on this blog to see why we include them and how they differ from other scrubs.