Sunday, December 4, 2016
Weekend Wondering: Measuring in drops?
In this post, Preservatives, tafchk asks: How do you know how many drops to use for a given percentage please?
The short answer is that we don't use drops in our recipes or products, so I don't know that information.
We don't use volume measurements like drops for our ingredients - like preservatives, cosmeceuticals, essential oils - because it's simply too inaccurate. Is that drops from an eye dropper, a large eye dropper, a large or small pipette, an orifice bottle, a dropper bottle like the picture, and so on? Drops aren't the same out of each container, so to tell you that 10 drops of liquid Germall Plus is equal to 0.5 grams would be completely wrong because that only applies to my eye dropper, pipette, or bottle.
Viscosity plays a huge part as well. Every oil is slightly different than the next, so to say that every essential, fragrance, or carrier oil is x drops to 1 gram is incorrect. Avocado oil is much thicker than fractionated coconut oil, and you'd end up using too much or too little even if we were using the same dropper.
Lest you think this isn't a big deal, there are a few huge problems you'll encounter if you want to measure in drops. The first is accuracy. If you're dealing in drops for essential oils, you could be using too much or too little of what you want. You might be adding too much oil to a lotion, which can throw the emulsification out of whack. Or you could be adding too little preservative, which can lead to icky contamination. All of these are concerns when you're measuring by volume or other inaccurate methods.
The third is the ability to duplicate what we've done before. If you measure out 10 drops of something, are you sure the next time you make it you'll use the same dispensing method and same vicosity ingredient to end up making the same awesome product?
By using grams, we ensure we get exactly how much we want in a product and can duplicate it again. You can convert those drops in a recipe into weight by measuring them on a scale and making a note of how much you used. You might need a tiny scale - see tomorrow's post for information on those - but it'll be worth your time to figure it out.
As an aside, I know there are standardized measurements in different fields like pharmaceuticals and medicine for what constitutes a drop, but those aren't applicable to cosmetic chemistry. And even then I couldn't find information on a standardized measurement that works for every possible oil.
Why we weigh our ingredients
Weight vs volume