Thursday, January 26, 2012

How can you tell it's a good recipe? Do the math!

Jenna wrote as a comment in this post on recipes: I have created this recipe and have made it before. There were moments that it worked and moments that it didn't. So after finding your blog a short time ago, I finally have the courage to ask about my recipe. 

water 300g 
ewax 25g
shea butter 40g
sweet almond 52.5g
jojoba 52.5g 
preservative 2.5g
vit e 30 drops

The first thing we need to do is work on the math for this recipe and put it into a percentage so we can see if we have the right amount of various things. How do we do that? Add up all the numbers we have - the water is 300 grams, the e-wax 25 grams, and so on (leave out the Vitamin E as it's hard to know the weight of 30 drops), and figure out if we have enough of each ingredient in the mix.

The ingredients in this lotion total 472.5 grams, so this recipe ends up being...
63.5% water
5.3% e-wax
8.5% shea butter
11% sweet almond oil
11% jojoba oil
0.5% preservative
0.2% Vitamin E (I had 0.2% left over with the rounding, so I figured I would put it in the Vitamin E)

What can we tell about this lotion now? It's a high oil lotion - 63.5% water phase with 30.5% oil phase - and it needs more emulsifier. If we use the 25% rule from Polawax (we use 25% of the oil phase in our emulsifier), we should be using 7.625% emulsifier in the lotion to make sure it's emulsified well. (It's recommended for some emulsifying waxes NF that aren't Polawax that you use 1% more in a lotion, so really, you want to use 8.625% e-wax in the recipe). So the first problem here is that we aren't using enough emulsifier. (And this would explain why it failed. Sometimes

My second suggestion is to add a thickener. Some people call cetyl alcohol (or any fatty alcohol) or stearic acid a co-emulsifier - that's not really true, but it will help keep the product emulsified. And it will thicken it up, which is a bonus! I'd remove 3% from the oil phase and add 3% cetyl alcohol or stearic acid. Which one you use depends upon your goal for this product. If you want a foot cream or body butter that stays on a long time, I'd go with stearic acid. If this is a body lotion or hand lotion that you want to glide on easily, cetyl alcohol. I've removed 3% from the sweet almond oil to make up for the 3% cetyl alcohol or stearic acid, but you could reduce the jojoba or the shea butter instead.

You have the preservative at the right level if you're using something like liquid Germall Plus, at the low end for something like Germaben II, and too low for Optiphen. (Check out the chart for more information on preservative suggested usage levels).

Why did the recipe work some times, but not others? Because Jenna likely had the two other types of emulsification - heat, mechanical, and chemical - going for her, even when the chemical emulsification didn't work!

Let's re-write this recipe!

60.2% water

8.5% emulsifying wax
8.4% shea butter
8% sweet almond oil
11% jojoba oil
3% cetyl alcohol or stearic acid

0.5% preservative
0.2% Vitamin E

Here you go, Jenna! Let us know how it worked!

Related posts:
Calculating percentages from weight. 
Convert recipes from percentages to weight. 
Why do we weigh our ingredients?
Troubleshooting an epic lotion fail!


jenna said...

Thank you so much for helping me out with this!! I've never used a thickner (obviously) with my lotion and I'm a little nervous. Should I be? This is more of a body and hand lotion. I have a different recipe for body butter, which has been a positive experience so!! I do use Optiphen for a preservative, but I've been thinking of changing it to Liquid Germall Plus. I also use Btms-50...really enjoy using this since it comes in little pellets. Do I need to change that as well?

I'm excited to try the new recipe, but have to wait and buy ingredients. All my oils went rancid and I'm totally bummed!!

Nancy Liedel said...

This kind of post is fantabulous. It reinforces basic rules and you should never be so confident you create without thinking about the rules.

Once you understand the rules, we know which ones to keep and which ones to razz-berry.

chowsr said...

Jenna, a trick I use is to add black pepper essential oil to all my carrier oils to keep them from going rancid. Black pepper oil is an amazingly good antioxidant comparable to and in many cases better than BHT and BHA. You can use vit E, but that gets expensive quickly. Also, if you store your oils in a cool dark cupboard in dark bottles they will also last longer.

Susan Barclay-Nichols said...

Hi chowsr! Does the EO smell even slightly like pepper? I ask because I hate the smell of pepper so much that I can't stand having it in a bag in the car when they accidentally give it to me at McDonald's. I have to pull over as soon as possible to throw it away. So not really an option for me, I think! But a great idea for other people!

Thanks for posting the study in this post. Interesting reading!

jenna said...

JOYOUS!!! Thank you so much for your help!! My lotions turned out great. They smell better, look better and I've had a little bottle of some just sitting out. I look at it to see if there are any far nothing and it's been a month!! I didn't use the stearic acid, but put some rice bran oil and shea butter. I promise that I measured it out to 100% before cooking. I read your blog so much and it's so helpful. Thank you, again!!

Susan Barclay-Nichols said...

Congratulations, Jenna! How good do you feel?!?

jenna said...

I feel fabulous!!! And very proud of myself for not giving up. I was really frustrated about how it turned out when I first started. I did try to find someone to ask questions, but I couldn't find anyone that I was comfortable with. I found your e-book (which I just purchased!!) on lotion crafter around the holidays. I kept coming back and reading and reading on your site before I asked my questions. I really felt comfortable asking you, as you seem to know what you are talking about. You go thru the whole science of making lotions and that is what I was looking for. So thank you, thank you, thank you! There is so much more that I want to learn, like making moisturizers, body butters and much much more. My dream is to have my own little line of products. One day.... :)

Anonymous said...

Just to help others out, the equations for the math Susan does is as follows:

Emulsion Equation
25% of oil phase=X
.25 X 30.5 oil phase=7.625 emulsifier
We always turn the percentage into a decimal by moving the decimal place to the left.

Weights to Percentages
Add the total number 472.5 grams
Divide each weighted ingredient by the total, I.e., 300g water/472.5 total grams=.6349
Turn the decimal into a percentage by moving the decimal point two places to the right-63.49%
Round up to the nearest 100th if you'd like (if applicable).-63.5%

Hopefully this helps and is explained in more layman's terms.


Connie said...

I have never commented on your blog before, buy I have read much. I love it. I am confused, however, about the percent of emulsifier relates to total percent. I understand that amount of Ewax is 25% of % of oils. But isn't the Ewax considered part of oil phase? When I add that in, isn't it going to change all my percents? I may be overthinking this. :/

Susan Barclay-Nichols said...

Hi Connie! I'm answering your question more detail next week as Monday, Septemver 11th, 2017's Weekday Wondering. The short answer is that you are overthinking it a bit, to be honest.

Emulsifying wax is incorporated in the heated part of the oil phase, but it's not part of the "oil phase" or the oil soluble ingredients that need to be emulsified into the product. We need to know the total of the oil soluble ingredients in a lotion to figure out how much emulsifier we need to use. Calculate everything that has to be emulsified in your formula. This includes things that might be in the cool down phase. Then figure out 25% of that amount and use that much Polawax in the formula.

You don't get the final total of the formula until you add the water, which is always the last ingredient to be added.