It really does matter. If we look at Vitamin E, it should be about 1 ml = 0.90 grams. So let's say you need 1 gram for a 100 gram batch of lotion to make sure that the product has the maximum anti-oxidizing power. Adding 1 ml means you don't have the maximum amount. Let's say we take that to a larger amount - we need 10 grams in 1000 grams. If we use 10 ml, we're only getting 9 grams. That's a big difference!
If we look at something like liquid Germall Plus, if the safe as used rate is 0.5%, and we go using more than that, could we be courting skin issues by using too much? Or are we asking for preservation problems if we use too little? If we want to use no more than 1% fragrance oil and we use 1ml, is that too much or too little? If we want to use glycerin, could that little bit extra make it feel sticky? It can mess up the emulsification of something if we aren't taking all the ingredients into account. It can cause your toner to have precipitation at the bottom because something didn't dissolve completely. It can take some ingredients from the "safe as used" to a slightly higher amount that could irritate skin or ruin the chemistry of your product.
In the grand scheme of things, using 0.1% more or less of something isn't the end of the world, but it can cause problems in the future. When you make a larger version of that lotion, it might not feel the same if you've been using less than the suggested amount of oils! Or it might not suds as well if you're using less surfactant than the recipe suggests.
How do I figure out the volume of a recipe?
Weight vs volume
How to figure out the volume of a recipe?
How do we convert from percentages to grams?
Measuring small amounts?
beeswax is not an emulsifier, Luna Love Farm writes: I am a massage therapist by trade and we use either sesame oil or coconut oil as our massage oil, both of which are naturally anti viral and anti bacterial. Would that not help with the contamination issue? If the water is suspended in the oil, then at least the outer circumference of that water droplet would become 'safe' by being in contact with the anti cootie properties of the oil? I am assuming that the fluid within the droplet would then become safe?
I wanted to address the issue of our carrier or exotic oils and butters having anti-bacterial or anti-microbial properties. Although some of them may have low levels of those qualities and might work neat on the skin, they cannot preserve a lotion. (We see the same thing with honey...) When we're making products that contain water, we need to use a broad spectrum preservative suitable for that product.
What is a broad spectrum preservative? It means it it kills off bacteria, mould, yeast, and other fungi or a broad spectrum of beasties that might contaminate our productsThe preservatives we buy are called synergistic preservatives, which are combinations of preservatives intended to eliminate all the various contaminants we could see in our products. If you see a product that is just one preservative - for instance, sodium benzoate or phenoxyethanol - then it's not a broad spectrum preservative, and you'll have to combine it with something else to get all the beastie killing power you need!
Anti-microbial effects of virgin coconut oil
Novel anti-bacterial effects of coconut oil
In vitro antimicrobial properties of coconut oil on candida species
Preservative section of the blog
Choosing a preservative
Are the preservatives in our ingredients enough to preserve the entire product?
If some essential oils are anti-microbial, why aren't we using them to preserve our products?
Join me tomorrow for more comments!