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Thinning out an emulsion…why does it keep breaking?
I am probably doing something quite unorthodox, but I am hoping someone here can help.
I am making a simple formulation (at least it seems that way) for a facial toner.
This formula includes both oil (Vit E (0.5%), castor oil (1.0%), and oil soluble calendula extract (1%), and essential oil of different kinds (varies depending of type, Rose: 0.5%; Lavender 0.45%; etc.) and water (along with allantoin (2.5%) and glycerin (10%)). I am using lethicin (5%) as an emulsifying agent.
I first soak my lethicin in a portion of the water, then blend to start the emulsion process. Then add my oil ingredients to this…no problem.
I then dissolve my allantoin in water and glycerin and add those (at this point I have only used about 15% of the total water, so the mixture is not thick, but obviously too thick for a facial toner).
I then, trying my best to keep the temps around 60-65C start to add more water, slowly. This seems to go fine until about halfway when the whole thing breaks down.
1) Is this process possible or am I trying to do something that is either very difficult or impossible?
2) If it is possible, then what am I doing wrong, or what might you guess that I am doing wrong?Thank you!
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4 Replies
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You are trying to do something that is impossible, at least with your current ingredient dec.
What you are starting out making is first a water-in-oil emulsion. There’s nothing wrong with that, and lecithin alone might work to stabilize it. But as you keep adding water, the lecithin/oil interface between the water droplets gets thinner and thinner, and at some point the interfaces start to break. A water-in-oil emulsion can only stand a little bit of this before it inverts, and becomes an oil-in-water emulsion, which is exactly what’s going on here. Since lecithin is completely unable to sustain an oil-in-water emulsion by itself, your whole batch falls apart.To keep your formula stable, you are going to need to add at least one, and preferably two or more, oil-in-water emulsifiers. You might even want to look into emulsifiers that will let you make a micro-emulsion (really tiny oil droplets), which will be more fluid and yet possibly more stable than an ordinary macro-emulsion. -
Thanks Bobzchemist! I appreciate your comments and I feel a little less frustrated now.
I have looked into micro-emulsifiers, but find little help there as far as specific names of products. Also, I read something that stated that these ingredients are primarily used for cleansing products because of their effect on the skin.
Do you have any suggestions on which micro-emulsifiers would be best to try?
Also, my numbers above are slightly off, like by one decimal point in most cases…oops
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I like Sensient’s SOLUBILISANT LRI, but there are others. Where are you located?
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I’m in Beijing, China. I am working on getting this together and have done soft launch to friends, who like the simple version of the product. I am trying to make it more in line with what I believe would be an excellent and unique product. I have a background in herbal medicine (including Chinese medicine) with over 20 years of practice experience and prior formulating experience, but this is the first time I have tried to product a product like this, so I am floundering a little.
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