Centrifuge test failed for cream emulsion

Formulating

Centrifuge test failed for cream emulsion

Posted by nshu_14 on April 15, 2025 at 2:49 am
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%
- This discussion was modified 17 hours, 27 minutes ago by nshu_14.
Fekher replied 4 hours, 25 minutes ago 6 Members · 9 Replies
9 Replies

mikethair

Professional Chemist / Formulator
April 15, 2025 at 3:16 am

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.
Richard

Member
April 15, 2025 at 3:18 am

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.
- Richard
  
  Member
  April 15, 2025 at 3:25 am
  
  Having reviewed again I would reduce your fatty alcohols in the formulation.
  - nshu_14
    
    Beginning formulator
    April 15, 2025 at 3:33 am
    
    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?
    - Richard
      
      Member
      April 15, 2025 at 3:44 am
      
      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%.
      - nshu_14
        
        Beginning formulator
        April 15, 2025 at 4:21 am
        
        Increasing oil and shea butter will not lead to a very sticky/oily feeling post-application??
        
        Aniela
        
        Member
        April 15, 2025 at 5:20 am
        
        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?
ketchito

Member
April 15, 2025 at 6:15 am

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%.
Fekher

Professional Chemist / Formulator
April 15, 2025 at 3:53 pm

Supposed to be stable same question which emulsfier is used?