I say it all the time but I’ll say it again.
I LOVE GETTING YOUR EMAIL QUESTIONS.
The teacher in me loves to answer questions. I just love to help and spread knowledge! I especially love when people ask me questions about topics we both love…like making beauty products!
Many of the questions I get are about math and proportions of ingredients. In one of my favorite emails the author said she was “math challenged.” Fear of math is pretty common. I completely understand. In this post, I’m going to quickly discuss how to do the math you need to make lotion. It’s easy. At the end, I will share an ingredient ratio guide for products.
Let’s do a quick lesson on percentages.
If a manufacturer says that a preservative is effective at 1% concentration, what do you do?
If you are making batches of lotion to use at home, you’re probably making fairly small batches, probably no more than 20 ounces. Measuring 1% of 20 ounces is easy. First, move the decimal 2 places to the left.
1% becomes 0.01
Now you can multiply.
0.01 x 20 ounces = 0.2 ounces of preservative
I don’t like using ounces because they’re not precise enough to me. I like to use grams. There are 28.3495 grams in an ounce. So if you’re making 20 ounces,
20 x 28.3495 = 567 grams
0.01 x 567 grams = 6 grams of preservative
If a recipe calls for 60% water, you do the same thing. First, move the decimal 2 places to the left.
60% becomes 0.60
0.6 x 20 ounces = 12 ounces of water
or, in grams
0.6 x 567 grams = 340 grams of water
Okay, good. Now that we’ve gotten that out of the way, here is a great ratio guide. The grams given are for making a batch that weighs 20 ounces/567 grams.
Notice that I called this a ratio guide, not a stone tablet of ratios. You may change these. One of my favorite body cream recipes doesn’t follow this guide too closely. I wanted it creamier so I increased the butter and emulsifier, decreased the water, and left out thickener. Please play with proportions! If you ever want to write and customize your own recipes, you have to be willing to experiment with proportions. That’s the only way to get information!
I hope this answers any math questions! As always, please email firstname.lastname@example.org with questions.