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Need help with emulsion sedimentation problem
I am having some trouble with my skin cream. The end product appears and applies well, however when I place it in a test tube and leave it for a couple of hours it begins to form a runny layer of yellow oil on the top. I tried reducing the concentration of oils but this did not resolve the problem.
Water phase constitutes distilled water about 73%
Emulsifiers 4% (peg-40 hydrogenated castor oil, ppg-26-buteth-26, sorbeth-30)
Emollients 8% (plant oils)
Thickener 1.2% (carbomer)
Alcohol 2%I have been adding neutralized carbomer after emulsion. I will try to add it into my water phase or right at the start of emulsion instead to see if that helps.
Also I am currently making small samples about 50grams and manually stirring with a rod instead of using a homogenizer.
I heat both the water and oil phases to 70 degrees celsius before combining them.
Over time my cream seems to be melting and disintegrating instead of keeping its form. Any tips?
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12 Replies
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manually stirring with a rod instead of using a homogenizer.
- not likely to work. 1.2% carbomer is a lot. Get rid of the alcohol. Use high shear. And where is the preservative? -
I use Optiphen Plus for the preservative. Why must I remove the alcohol?
I tried using xanthan gum instead of carbomer and I do not notice the problem, however when I apply xanthan gum on skin it begins to create flakes.
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What Carbomer are you using and what neutralizer?
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I am using prenuetralized carbomer from lotioncrafter.com that does not state what it is neutralized with.
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what use is the alcohol? it has no function.
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It has been shown in studies to increase skin penetration along side Isopropyl Myristate
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I don’t see any of that in your formula.
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Isopropyl Alcohol and Propylene Glycol may be decreasing viscosity, that is why I used a higher percent of carbomer to achieve the thickness I wanted. I will try to use my electric stirrer and add the carbomer during emulsion this time to see if it is more stable. If it is not, maybe increasing the emulsifier concentration will help. I am out of ideas after that.
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You probably need a different emulsification system. The system you are using is better suited for solubilizing oils in a micro emulsion and if this were the case, you would need a much higher level. It looks very similar to the Sorbisant system from Sensient. Even with a proper system, you will still want to vortex in the carbomer (ie use a continuous mixer with a propeller blade preferred). Feeling that 2% alcohol is going to increase skin penetration (what active are you trying to increase penetration of? It is not likely will the emollients or oils to be significant) is really a bit of marketing puffery.
Ask yourself: “What Cosmetic benefit is this product delivering to my end user? What actives are delivering this benefit in such a way that it is a credible claim?”
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I need a higher level to solubilize 8% plant oils?
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Change emulsifier and thickener to Ultrez 10—add to water use 1 percent with .3 xanthan gum—-combine both phases at 70C-cool to 50C and add 1 percent triethanolamine to thicken and form cream.
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No, you need an entirely new system. It is not the concentration but rather the suitability. The Sentient Cosmetics product, as well as a similar product or the Ressasol product (very similar from Res Pharma), are properly used to solubilize finite amounts of Essential oils, Fragrance ingredients, and similar type products into a water base by creating a microemulsion. I have never seen it used as a Primary emulsifier. I have not tried it, but it is likely you would need at least 24-32% of the solubilizer to create the microemulsion. At that level, it would be pricey, have a negative effect and would be easily replaced with a more appropriate emulsifier. I have not used either product in years so others may want to weigh in.
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