In this post, Nancy asks: Okay, here goes. I feel so dumb asking this question. If you make a facial serum out of oils and extracts with vastly different specific gravity, how do they stay together without shaking, or an emulsifier? I've seen plenty of shops on Etsy selling these. I make a product, but I use Cera Bellina to hold it all together. Not a true emulsifier, but a nice product that you should get and play with.
I make my serums creamy, not clear and just oils and oil soluble extracts. If I do that, my E settles on the bottom. It's frustrating me to pieces, cause non of them seem to have a problem, although I'm not sure I'd want to do that, mix just oils and pray the mix comes out evenly when pumped and I'd NEVER ask a customer to shake anything. GACK!!!!
How is this a stupid question? Is it opposite day? (And if it is opposite day, shouldn't we be calling it normal day?) This is a great question! But I really don't know the answer to it. You can see my bath oil above just after I made it, and it separated into different layers of the oils over time. (I didn't get a picture of this, darnit!)
I have an order with Lotioncrafter sitting at the border that contains the Cera Bellina and new emulsifiers, amongst a few other things! I can't wait to play!
specific gravity? It's a way of measuring if something weighs more or less than water. Pure water at 4 Celsius is our baseline for specific gravity and everything else is compared to it. Water weighs 1000 grams per litre - 1 kg per litre - or 1 gram per millilitre. So a teaspoon or 5 ml of water weighs 5 grams. A tablespoon or 15 ml of water weighs 15 grams. A cup of water at 250 ml weighs 250 grams.
If something is listed as being less than 1, it weighs less than water per gram. If something is more than 1, it weighs more than water per gram. If something has a specific gravity of 1.03, it means it weighs 1.03 grams for every 1 millilitre or 1030 grams per litre.
Specific gravity is the reason that oil floats on top of water. A lot of the oils we use have a specific gravity of 0.90 to 0.95, which means they are lighter than water, so they float to the top of our product while the water settles on the bottom.
Most of our oils are around 0.90 to 0.92, so they're really quite similar in nature, which could be one answer as to how the Etsy sellers are keeping their products together. If they use all vegetable oils and no extracts, the entire product will likely be very very close in specific gravity. Or they might be using our natural inclination to shake bottles before we use them. Or they haven't watched their product over time to see the separation. Or they don't know any better.