Home Cosmetic Science Talk Formulating pH 4-4.5 with citric acid: irritating?

  • pH 4-4.5 with citric acid: irritating?

    Posted by Bluebird on June 5, 2023 at 2:32 am

    Hi I’m thinking of making a body spray w/ pH 4-4.5, with the pH adjusted using citric acid.

    Does anyone have a reason/experience/knowledge to think that this may be unusually irritating?

    abdullah replied 6 months ago 3 Members · 4 Replies
  • 4 Replies
  • graillotion

    June 5, 2023 at 2:42 am

    I am not a microbiologist….but I think you will get most of the antimicrobial benefit at 4.6 to 4.8. Why not slide up a bit (unless something else was driving the target pH)? I would also mention there might be a slight advantage of hitting the target pH via lactic acid, over citric.

    When I tested various acids for dropping the pH of an emulsified deo to 3.8, lactic produced the best results for subjects with sensitive skin.

    Good Luck.

    • This reply was modified 6 months ago by  Graillotion.
    • Bluebird

      June 5, 2023 at 7:35 am

      Very interesting, pretty much everything you said.

      First, you’re spot on-yes the pH is to decrease the microbial load.

      Never thought pH of such a fine, specific range may have such an effect.

      May I ask why or where you got this idea?

      So far I’ve tested pHs 4, 4.5, 5, 5.5, and 7,

      and from those pH 4 was the best, followed by 4.5, which was why I picked those numbers.

      But if 4.6-4.8 has better effect, well that’d be awesome, as I feel pH of 4 is a bit lower than I’d like for skin.

      What is an “emulsified deo”? Is that water type w/ oil in water stuff as deo, ex, a spray type?

      Sounds like lactic acid is another thing to try.

      I had picked citric over lactic because the former is smell-free while I read the latter is not, so definitely good to know that LA may be better for sensitive skin.

      You said you used LA to drop the deo pH to below 4-why didn’t you use 4.6-4.8? 🙂

      • This reply was modified 6 months ago by  Bluebird.
  • graillotion

    June 5, 2023 at 2:53 pm

    I did not at all mean to infer…that the continuation of lowering pH will not enhance micro. It will continue to diminish the happiness of bugs as you go lower. The numbers I suggested…are the ultimate compromise. My numbers also assume you are using a primary preservative…and not just pH as your prevention system.

    Just remember…pH of coca cola…is 2.5. Never heard of people heading to hospital burn unit…when some is spilled on their skin. I have even heard of people…that drink the stuff! 😉

    Emulsified deo….is a soothing cream deo, devoid of irritants. It is simply a different delivery system for the actives. One additional benefit…it allows for the use of water soluble ingredients/actives. I have never been able to use commercial products, other than aerosols, this system allows me to use a more eco friendly option.

    As I said earlier… continued lowering of pH … does decrease microbial happiness, there was performance enhancement with dropping of pH to the level I ended with. One of the biggest players in this space…also uses this pH. Good luck… picture is of major commercial deo…

  • abdullah

    June 5, 2023 at 9:59 pm

    I would say go for pH 4 and never above pH 4.8

Log in to reply.