Dissolving Salicylic Acid for Dummies

So, I'm in Canada which allows SA to be used at up to 2% in skincare. 

I'm attempting to formulate an exfoliating mask (clay based O/W emulsion).   

I have sodium citrate, citric acid, octyldodecanol and powdered SA. But what's the method?

Any suggestions would be really helpful since I have a feeling that throwing it into the water phase and forgetting about it is potentially disastrous. 

Comments

  • MarkBroussardMarkBroussard Member, Professional Chemist
    @EliseCortes

    What are you using as your Oil phase?  It's probably much simpler than you think.  

    Method 1:  Dissolve the Salicylic Acid in your Oil phase, which can include Octyldodecanol.  Add 1% Sodium Citrate to your water phase.  When you combine to make the emulsion, the SA will be solubilized.

    Method 2:  Dissolve the SA in 1,3-Propanediol by heating it and then add this to your hot Aqueous Phase that includes 1% Sodium Citrate right before you combine the Aqueous Phase with your Oil Phase to form the emulsion.  Again, you can include Octyldodecanol in your Oil Phase.
    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
  • MarkBroussardMarkBroussard Member, Professional Chemist
    @EliseCortes

    Forgot to mention, if you observe any precipitation, just raise the pH to 4.0 or so, that will help ensure the SA stays in solution.  Just add some Sodium Lactate to get the pH up.
    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
  • @MarkBroussard - Thanks for that!

    I did a few attempts of a water based clay-gel mask (lactic acid 4% / salicylic 2%). At the time the pH meter hadn't arrived yet. Everything looked good until I threw the clay in at the end and it erupted like a baking soda volcano. 

    If I'm understanding correctly, this time around with the O/W emulsion, the phases should look like this:

    WATER
    Water
    Allantoin 0.5%
    Lactic Acid 4%
    Sodium Citrate 1% (or more due to presence of lactic acid)

    OIL (heat to 80-85 Celsius to ensure complete solubility of SA)
    E-Wax NF
    Octyldodecanol 6%
    Salicylic Acid 2%

    COOL DOWN
    Optiphen Plus
    Tetrasodium EDTA
    Silt 
    Kaolin

    Want to change the chelating agent and the emulsifier up once my next ingredient order arrives but the general principal should be the same.

  • BarsikBarsik Member
    Most clays are alkaline, so it maybe a reason for volcano :)
    Check this post
    https://chemistscorner.com/cosmeticsciencetalk/discussion/753/clay-masks-and-ph-how-to-avoid-skin-irritation
     
  • @Barsik - No doubt. Hadn't seen that thread. Thanks.
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