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Centrifuge test failed for cream emulsion
Hii everyone,
I have prepared a cream formulation and did centrifuge test at 3000 rpm for 30 min. For this, a very thin layer of oil is seen on top for one of the samples while for my other sample clearly 2 phase is visible (difference is in the type of emulsifier/surfactant used). How, in your opinion, I can fix it? Where am I going wrong? Also, please suggest a thumb-rule for oil:emulsifier ratio as I cannot find a detailed and thorough information on it. Would highly appreciate your insights (the great formulators here 🙂 )
Below is the composition of the sample with thin oily layer (active matter):
OIL PHASE:
CCT (triglyceride): 12%
Surfactant with HLB 11: 5%
Cetearyl alcohol : 2%
stearyl alcohol: 4%
Shea butter: 4%
WATER PHASE:
Water: qsp
Glycerin: 5%
xanthan gum: 0,4%
COOL DOWN PHASE: Preservative + Perfume + Vit E = 2,3%
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This discussion was modified 1 day, 21 hours ago by
nshu_14.
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This discussion was modified 1 day, 21 hours ago by
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18 Replies
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Have you thought of formulating a face oil instead of a cream? In my 20+ years experience as the co-founder and Master Formulator with a brand I founded in 2006, oils are more effective and less problematic.
The key difference with oils is that the actives are present at a much
higher concentration as they’re not diluted. This means they have a more
tangible effect on the skin. And, there is no need to add synthetic preservativres which for some can cause skin irritation.The face oil products I formulated, manufactured and distributed globally 2006-2024 were fantastic sellers and very profitable.
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I would look to reduce your primary emulsifer percentage to around 4.5% and add some Glyceryl Stearate NSE, around 0.6% and then play around from there depending on what you find.
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Having reviewed again I would reduce your fatty alcohols in the formulation.
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Thank you @Richard I dont have Glyceryl stearate NSE, can Glyceryl stearate do the job? Also, if I include Glyceryl stearate 0,6%, will it act like a stabiliser? and shall I remove any of the fatty alcohols?
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At this stage I would not add Glyceryl Stearate. Replace some of your fatty alcohol with vegetable oil, you can even increase the shea by 2-3%.
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Increasing oil and shea butter will not lead to a very sticky/oily feeling post-application??
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Considering you’ll reduce the fatty alcohols and add more shea, it shouldn’t make a big difference.
What’s the INCI name of your emulsifier?
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To clarify, “it won’t make a big difference” was meant for the skin-feel, not the stability.
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Thank you for your answer. I am using APG as the only emulsifier. I would like to test if our APG sole is enough for the emulsion.
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Had to google APG😇- the ones BASF makes have “excellent foaming and cleansing properties”, aka a proper surfactant.
So why APG in a cream as the main emulsifier?
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Ooops, sorry I wrote the abbreviation.
Because I am curious about glucosides in emulsification and I only have those available as a “greener” option.
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This reply was modified 15 hours, 5 minutes ago by nshu_14.
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This reply was modified 15 hours, 5 minutes ago by
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All right, but APG is still vague: there are quite a few of them.
Also, wouldn’t that be a foaming emulsion?
@ketchito , would you be so kind to make some light here, please?
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I’d also would like to know what your emulsifier is (they vary in structure despite the HLB number). Also, I wouldn’t reduce your fatty alcohols (they are your structuring agents) but would use cetearyl alcohol at 4% instead (if you’re using the 50:50 version) and 2% of cetyl alcohol. Also, I’d reduce the shea butter to 2% (butters are hard to emulsify) and your CCT to 6%.
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Thank you @ketchito. Your comments are always helpful. I will give a try to your suggestions. Do you think increasing the emulsifier to more than 5% active content would help further?
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It depends on which emulsifier you’re using 🤓
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Supposed to be stable same question which emulsfier is used?
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When oil separated, it always means your emulsifier is not enough or is not working.
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CCT (triglyceride): 12% Never used but assuming its the lipid
Surfactant with HLB 11: 5% Is this your emulsifier? If so you may have to tweak, you need the right amount for the lipid qty
Cetearyl alcohol : 2% Looks good
stearyl alcohol: 4% Ok but you don’t always need two types of fatty alcohols, this might make it too thick
Shea butter: 4% This is good amount, you can even use more but butters are fickle so you have to experiment. Depending on formula, using less wouldn’t give it a lux appeal since shea is very highly regarded
WATER PHASE:
Water: qsp
Glycerin: 5% No problem
xanthan gum: 0,4% This is sometimes too much but good for stabilizing fickle formulas
COOL DOWN PHASE: Preservative + Perfume + Vit E = 2,3% 2% is high percentage preservative and 3% is high percentage perfume and vitamin e. Make sure these ingredients are compatible with the formula and put in during the right phase. My lotions would always destabilize when I used optiphen during the cool down process, guar helped but gums can also pill.
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