Home Cosmetic Science Talk Formulating General Adjusting pH when percentage of an ingredient has to stay constant

  • Adjusting pH when percentage of an ingredient has to stay constant

    Posted by hatasamatter on January 17, 2024 at 12:41 pm


    I’m an aspiring formulator and I have a newbie question about adjusting pH. At the moment I’m experimenting with various thickeners (e.g. Xanthan Gum, Karaya Gum, Magnesium Aluminium Silicate …) and I’d like to compare the viscosities of different thickeners at a certain percentage (e.g. viscosity of 1% Xanthan Gum in water vs viscosity 1% smectite in water).

    How should I go about adjusting pH at the end? As pH adjusters change the formula and the percentage of existing ingredients in the product, is there a way to calculate how much (e.g.) citric acid I need so that percentage of thickeners doesn’t change?

    Thank you so much!!

    hatasamatter replied 1 month, 2 weeks ago 3 Members · 3 Replies
  • 3 Replies
  • graillotion

    January 17, 2024 at 1:52 pm

    Your pH adjustment is typically measured as Q.S…. Quantum satis.

    This means you use enough to hit the targeted pH. It is typically not part of the calculation to 100%…unless it was a formula that was using lots of acid for another purpose. But for simple adjustment…it is not a calculation usually. Just put your meter in….and adjust till you get where you need to be.

    • This reply was modified 1 month, 2 weeks ago by  Graillotion.
  • markbroussard

    January 17, 2024 at 5:55 pm


    The way I usually do this is measure 1 gram of Citric Acid in a container. I then add Citric Acid a small amount at a time while measuring the pH. When I hit the desired pH, I then measure the remaining Citric Acid and I then know how much I added.

    With liquid pH adjusters such as Lactic Acid you can do the same thing. Measure a known amount of the pH adjuster and then measure the amount not added to derive at how much you added.

  • hatasamatter

    January 18, 2024 at 9:30 am

    Thank you so much for your help!!

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