Home Cosmetic Science Talk Formulating pH drift in sunscreen formulations

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  • pH drift in sunscreen formulations

    Posted by adrianag on November 7, 2022 at 6:03 pm

    I noticed that with some sunscreen formulations that the pH increases overtime. Does anyone know why or how to prevent that? 

    adrianag replied 2 years ago 2 Members · 4 Replies
  • 4 Replies
  • Paprik

    Member
    November 7, 2022 at 7:28 pm

    What kind of sunscreens are you talking about? 

    Zinc Oxide will kind of self-regulate its pH to around 6.5 - 7.5.

  • adrianag

    Member
    November 7, 2022 at 7:40 pm

    I made a 20% ZnO sunscreen and the pH increased from 6.43 to 9.87 over a month. Someone mentioned a pH drift in mineral sunscreen and didn’t elaborate so I wanted to learn more. 

  • Paprik

    Member
    November 7, 2022 at 8:36 pm

    This looks like instability.
    We would need to know what else is in the formula.
    Something might be breaking down/reacting and raising the pH. 

  • adrianag

    Member
    November 8, 2022 at 12:42 pm

    Good point, thank you. The other ingredients are:
    Water, Hydroxyethylcellulose, propanediol, tetrasodium glutamate diacetate, sodium hyaulronate, Ammonium styrene/MA Copolymer. 

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