having a stability problem with this formula!

MelhattyMelhatty Member
edited July 8 in Formulating

The formula 

oily phase

argan 1%
jojoba wax 3%
pumpkin seed oil 1%
castor 1%
vit E 1%
shea butter 2%
cocoa butter 4%
peppermint oil 2%

cetostearyl alcohol 3%
peg 40 hydrogenated castor oil 2% (emulsifier)
ceteareth 20 3%  (emulsifier)


aqueous phase 

caffeine anhydrous 2.5%
glycerin 2.5%
propylene glycol 2.5%
xanthan gum 0.3%

cool down phase

D-panthenol 2% 
capsicum extract 5%
fragrance 

preservative a blend of methyl & propylparabens with k-sorbate 

distilled water 

this formula was doing very well for me but after 1-2 months the lotion becomes lighter than before and tend to separate I don't know why 

is there any thing wrong with using these two emulsifiers ?
any notes on the formula would be appreciated 

Comments

  • GabyDGabyD Member
    Don't know, but I've found Olivoyl to be an excellent emulsifier.
  • The HLB of your oil phase is 9.4, while the HLB of your emulsifiers is 15.1 which can lead to instability. You don't need to focus on HLB too much if you use commercial blends such as Glyceryl Stearate/PEG 100 Stearate and add polymeric emulsifiers for stability, but this is your custom blend. 

    Also PEG-40 HCO is a solubiliser and is not designed to stabilise such a high oil phase. I think you should change your emulsifiers. Try to replace PEG-40 HCO to glyceryl stearate and recalculate HLB.
  • ngarayeva001ngarayeva001 Member
    edited July 8
    Also, you have too much pepermint oil. It is a sensitiser. You also have too much of Vitamin E (unless it's acetate). It might work as pro-oxidant at this concentration.
    Panthenol is a claim ingredient and doesn't provide much skin benefits. You can reduce it to 0.1% because it will contribute to stickiness. You already have sufficient amount of humectants.
  • DoreenDoreen Member
    (...)  It might work as pro-oxidant at this concentration. (...)
    This probably isn't true. I know I've been sharing that graph several times, but upon closer look, it doesn't say much. In any case nót a substantial raise by far. I too should've studied it better.
  • @Doreen, thank you. I noticed there are different views on it. Please have a look at this video and comment what do you think:
    https://youtu.be/ioucAvsnziw

  • PharmaPharma Member, Pharmacist
    So far, I've observed pro-oxidant activities only with ascorbic acid. The pronounced effect of ascorbic acid regarding pro-oxidative effects has probably something to do with it easily changing chemical structure upon losing two electrons whereas phenolic compounds such as tocopheryl radicals are remarkably more stable and hence might not redox cylce.
    Also, pro-oxidative reactions depend on oxygen supply, available substrates, pH, and are boosted by free iron ions -> Minor changes to a formula can change it from stable to degrading or vice versa.
  • The video of the institute of the personal care science I posted above shows that at 2% it becomes pro-oxidant at a room temperature.
  • PharmaPharma Member, Pharmacist
    Just had the time to watch it: nice! Thanks for sharing!
  • PerryPerry Administrator, Professional Chemist
    @ngarayeva001 - I'm not sure the video shows that 2% makes it become pro-oxidant at room temperature. Unfortunately, they didn't have a proper positive control in the demonstration.  It would have been more conclusive if they showed what the formula would look like with 0% vitamin E.

  • MarkBroussardMarkBroussard Member, Professional Chemist
    Yes, I have seen this Vitamin E pro-oxidant at above 2.0% (actually, the value 0.2% was used on many occasions) comment many times in various threads ... and it is simply not supported by any scientific evidence.

    But, when I looked at the the graph being used as the evidence, it said no such thing.  It turns out that the proponent simply did not know how to read a graph and was misinterpreting it, and wildly incorrectly at that.  

    Same thing with this video, it says absolutely nothing about vitamin E being a pro-oxidant at any level.  What it does say is that some people have skin sensitivity to Vitamin E at levels above 2%, but that does not necessarily have anything to do with it becoming a pro-oxidant, but due to an allergic reaction.

    The other factor is that Vitamin E is a very dark brown color and when loaded into a formula at 2%, that alone will cause some discoloration of the sample at T0 at room temperature when compared to a sample with Vitamin E loaded at 0.5%.

    Looking at two different samples with the naked eye proves absolutely nothing other than one sample appears to be darker than the other and that could be simply a function of the fact that a cream with Vitamin E mixed tocopherols loaded at 2% will be naturally darker in color than a cream loaded with mixed tocopherols at 0.5%.
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
  • LisaSLisaS Member
    First of all, I want to say that I love the community support here! Also, I would suggest adding a chelator along with everything else that was suggested previously ^ Let us know how it turns out! 
  • MelhattyMelhatty Member
    Thanks for these informative suggestions 
  • MelhattyMelhatty Member
    Also, you have too much pepermint oil. It is a sensitiser. 
     how much peppermint oil should be added  instead of 2% ?
  • Check suppliers suggestions but EO’s are usually added around 0.25%
  • MarkBroussardMarkBroussard Member, Professional Chemist
    edited July 13
    @Melhatty

    The CIR recommendations for Peppermint Oil are < 3% in rinse-off products and <0.2% in leave-on products.  The real issue with Peppermint Oil is the Pulegone content which should be <1%.  If you look around, you can purchase Pulegone-free Peppermint Oil.  These are guidelines, not absolutes
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
  • DtdangDtdang Member
    @Melhatty try Sepiplus 400 
    it is freedom formulation. 
  • DoreenDoreen Member
    edited July 14
    @MarkBroussard
    The 0.2% graph is shared in the Making Skincare Facebook groups of Jane Barber and it is adviced there due to 'pro-oxidative' reasons not to exceed 0.2%.
    Instead of simply accepting it as truth, I should've studied the graph better myself. Lesson learned.
  • MarkBroussardMarkBroussard Member, Professional Chemist
    @Doreen:

    Understood.  The interpretation of that graph is simply incorrect, as you now know.  Good idea to be critical in looking at something someone has stated as gospel especially since anyone can post anything at any time on the internet regardless of whether or not they know what they are talking about.
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
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