Home Cosmetic Science Talk Formulating Need help with Lotion stability

  • Need help with Lotion stability

    Posted by CB007 on September 8, 2021 at 2:39 pm

    I have a formula that looks beautiful when first made but then after about ~4 months at room temperature, it starts to turn into this weird, bouncy, cottage cheese type texture.  Can anyone help me point out what the culprit may be?  My biggest challenge is that I have made multiple versions but I have to wait months to see if it remains stable.  I feel like the Stearic acid is the problem but I need some help/advice please…

    Water- qs
    carbomer 0.2%
    phenoxy/capryl- 1.0%
    PS20- 0.5%
    Allantoin- 0.5%
    CCT- 14%
    Stearic Acid- 3.3%
    Cetyl Alcohol- 2.9%
    Cetyl Esters- 2.5%
    Methyl gluceth 20- 2.75%
    Hydrogen. Cottonseed Glyceride- 2.3%
    Soybean Oil- 0.75%
    Sodium Hydroxide 20% solution- 0.55%
    Sorbitol 70%- 4%
    Ahnfelltia Concinna Extract (APT)- 2.00%
    Dimethicone- 0.95%
    Veg. Collagen- 0.75%
    Witch Hazel water- 0.1%
    Fragrance- 0.3%

    Abdullah replied 2 years, 8 months ago 8 Members · 9 Replies
  • 9 Replies
  • Graillotion

    Member
    September 8, 2021 at 6:28 pm

    You did not state the pH.
    What are you using as the chelate?
    Did you list your emulsifier?
    I would not suspect…stearic acid.  (But I would not include that much in anything I wanted to feel nice.)

  • CB007

    Member
    September 8, 2021 at 8:14 pm

    pH is around 6.5, viscosity ~10,000cps with TB@20rpm

    No chelator- as requested by client

    Cetyl Alcohol, Stearic Acid for emulsifiers…plus the Carbomer for water phase thickening.  This is an old formula so maybe I need to re-assess the emulsification system completely… 

  • crillz

    Member
    September 8, 2021 at 9:35 pm

    Also think seems like a lot of stearic acid, to go with cetyl alcohol, not surprised it would be thick.

  • Graillotion

    Member
    September 8, 2021 at 9:49 pm

    CB007 said:

    No chelator- as requested by client

    Cetyl Alcohol, Stearic Acid for emulsifiers…plus the Carbomer for water phase thickening.  

    Is client smart enough to know what a chelator does for the formula?  Do they know about options like GLDA or sodium phytate?  I can understand not wanting EDTA…..but sometimes the formulator has to step in and educate the client?  (Maybe that is just me.)

    Was 6.5 pH really the target?  

    Cetyl alcohol and Stearic assist with making an emulsion stable…but in who’s book are the primary emulsifiers?  And there are so many decent ones now days….that are considered….’natural’.  ;) 

  • Microformulation

    Member
    September 9, 2021 at 2:19 am

    CB007 said:

    pH is around 6.5, viscosity ~10,000cps with TB@20rpm

    No chelator- as requested by client

    Cetyl Alcohol, Stearic Acid for emulsifiers…plus the Carbomer for water phase thickening.  This is an old formula so maybe I need to re-assess the emulsification system completely… 

    The chelator is needed to augment the preservation system. You should never let the client compromise safety. If you stress it’s function they will generally relent.
    Perhaps they are saponifying the Stearic acid with the Sodium hydroxide to create a “soap.” However, if this is not the case, you do NOT have an emulsification system.

  • jemolian

    Member
    September 9, 2021 at 3:43 am

    It’s possible that the carbomer is not working out well with the co-emulsifiers thus creating the “cheesy” effect. I find that if i don’t test out and balance them properly that tend to happen when i use “carbomers”. No issues if i use other polymers.  

    Reference to the effect:

  • ketchito

    Member
    September 9, 2021 at 12:00 pm

    @CB007 Not sure if at a pH of 6.5, you’ll have all your Carbomer and Stearic acid neutralized. If the Stearic acid is not fully neutralized, you’ll see overtime, that your oils and waxes will start separating from your system. As mentioned previously in this thread, you should consider using a different emulsifier.

  • Quimico

    Member
    September 10, 2021 at 2:37 pm

    Can you separate the items by phase??
    1. Oil phase
    2 water phase, additives …..

  • Abdullah

    Member
    September 13, 2021 at 2:15 pm

    What do you mean by weird, bouncy, cottage cheese type texture? Can you show a picture

    Also as @Microformulationsaid, chelating agent is very important, especially with this preservative and this pH.
     Ask your client what they want. If they want you to just mix some specific ingredients and don’t care about the result then you should not care too. Just mix whatever they want and give them. 
    If they want a safe and stable product then tell then chelating agent is necessary. If they don’t like one then use another one

    For instability, if oil is separating then increase or change your emulsifier. If water separating then increase the viscosity of water phase. 

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