Question: Determining how much to use when working with powders, there's a discussion going on about calculations. Let's take a look at a few calculations today!
BASIC FIRST LOTION RECIPE
16% oil (sunflower, soy bean, rice bran, or olive oil)
5% shea or mango butter
3% cetyl alcohol
6% emulsifier (BTMS or Polawax)
1% fragrance or essential oil
0.5% liquid Germall Plus
When you are making a product, the recipe should total 100%. I know some of my recipes don't total 100%. Why is that? Sometimes it's because I'm trying to account for different preservatives having different usage amounts. Liquid Germall Plus calls for 0.1% to 0.5% usage, while Germaben II calls for up to 1% usage, so my recipes might say 0.5% to 1%, totalling 100.5%.
A recipe should not vary between weight and volume measurements. For instance, we don't want to see 5 grams of this and 4 ml of that. We want everything in grams or ounces (preferably grams as that's easier to convert from percentages).
To convert a recipe, trade the % sign for the word "grams" and you will get a recipe that weighs 100 grams.
If you want to make half the recipe, then divide everything in the recipe by 2 to create a 50 gram batch. For the lotion above, you'd have 34.25 grams water, 8 grams oil, and so on.
If you want 25 grams of the above recipe, divide everything in the recipe by 4 and get 17.125 grams water, 4 grams of oil, and so on.
If you want to make double the recipe, then you'd multiply everything in the recipe by 2, so you'd have 137 grams water, 32 grams oil, and so on.
Have fun formulating!