Sunday, September 10, 2017

Weekend Wonderings: Why don't we measure by volume? and more!

In this post, Creating products: A moment or two about recipes, Caroline said, I like using weight measurement for recipes because it is so much easier to measure than worrying about cups/teaspoons, etc. and also find it more convenient. However, there are a lot of recipes out there that don't use weight. This one particular recipe did use the 1/3 rule in that it asked for 1/4 cup shea butter, 1/4 cup coconut oil and 1/4 cup beeswax pastilles. I decided to weigh them and found that the shea butter weighed 44 gr, the coconut oil 54 gr and the beeswax (I used freshly grated, packed) 18 gr. So obviously, for a more accurate recipe, weight does make a difference since the density of the ingredients has a bearing on the end result. Is this correct or am I missing something?

You are completely correct! If you were to make the recipe you mention as a lotion bar, you'd have a sloppy mess as you only have 15.5% beeswax to harden the bar, versus the 30% we'd normally use.

To see what I did here - 44 grams shea butter + 54 grams cocont oil + 18 grams beeswax = 116 grams. I divided each thing by 116 grams to get the percentage. 18 grams beeswax/116 grams total = 15.5% rounded down slightly. Check out this post on how to figure out the percentages. 

This is how I generally explain it. If I say to use 1/4 cup cocoa butter, is that before or after I've melted it? Is that cocoa butter in pastilles, shards, or almost a fine powder? Measuring by volume is completely inaccurate for bath & body products and leads to ruined products. Instead, I suggest using 10 grams cocoa butter, and it doesn't matter what shape the ingredient might be as it'll always be 10 grams of cocoa butter.

As well, if you're doing things by weight, you use fewer containers and utensils as you're measuring straight into the container, rather than using 1/4 cup this and 1/3 cup that and all those teaspoons. So using the scale = less messy clean up after formulating fun! Woo!

What do you do if you find a recipe you're dying to make in volume measurements? Leave it alone. Find another recipe. I know, this isn't the answer we want, but it'll lead to far less heartache and far fewer wasted ingredients. If you find a lotion that has the preservatives in teaspoons, how do you know if you have enough in there? You don't, and neither does the person writing the recipe. There are so many good formulas out there written by volume that you can walk away from the ones that aren't done properly. (Check out this post on figuring out if this is a good recipe for not!)

Learn how to substitute one oil for another - there are very few situations in which you can't trade one liquid oil for another liquid oil in a formula - and one butter for another and use a formula you already know works with the oil you like.

There's one exception to this rule and that's all about mineral make-up and things like colourants or dyes. Oftentimes, we're using such tiny quantities that they can't be measured with even a tiny tiny scale that measures to 0.01 grams. So we use scoops and spoons and drops.

Related posts:
Everything you might need to know about formulas, including measuring by weight
Weight vs. volume
Specific density

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