• Formulating

  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, 1 month ago 2 Members · 4 Replies

  • ph-drift
  • sunblock
• 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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