Home Cosmetic Science Talk Formulating combining preservatives

  • combining preservatives

    Posted by Quinn13 on October 18, 2024 at 3:19 am

    Hi, looking for some advice on combining preservatives…

    I have some hydrosols and aloe vera juice that already contain sodium benzoate and potassium sorbate (@1%). I want to eventually use these ingredients in various products, including a face scrub formula that requires a ph of 6.2-6.7, but I want to use more effective/ph appropriate preservatives.

    The face scrub formula suggested the use of either:

    phenoxyethanol/ethelhexylglycerin;

    naticide, or;

    preservative eco/geogard ect.

    Could I combine one of these with the SB PS? If so, should the usage level be modified?

    There’s probably no simple answer, but if anyone has any advice/suggestions, that would be much appreciated!

    Aniela replied 1 week, 3 days ago 4 Members · 10 Replies
  • 10 Replies
  • PhilGeis

    Member
    October 18, 2024 at 8:26 am

    Twos simple answer - (1) forget the silly Naticide and 2) speak of specific chemicals - not commercial products.

    Phenoxy/EHG with Benzoate at a lower pH and EDTA should work. Add sorbic if you use that combination.

    • echidna89

      Member
      October 18, 2024 at 2:32 pm

      I have the same question, but one specific problem:

      In an aloe gel with sepimax zen for cosmetic purposes, how much Na Benzoate and K Sorbate should I use?

      I have the powdered form of each salt, so can I make a concentrated solution in distilled water and store that at room temperature to use within, say, two months?

      Thanks for the help!

      • PhilGeis

        Member
        October 19, 2024 at 5:06 am

        I wouldn’t unless you can confirm stability. Benzoate should be stable, not so sure the sorbate, and ironically you may need a preservative for the preservative solution.

        • Aniela

          Member
          October 26, 2024 at 12:04 pm

          Hello @PhilGeis ,

          My supplier sells a liquid preservative, comprising of: aqua 55%, sodium benzoate 30%, potassium sorbate 15%; pH is 8.8-9.8.

          Coming from a “natural” school, and after reading ALL comments/posts on this forum on preservatives, I might become a bit paranoid, but I feel like I want to understand everything: does your comment above applies to this combination as well? Or this combination is stable and can/does act as a preservative?

          Thank you, indeed.

          • PhilGeis

            Member
            October 27, 2024 at 3:05 pm

            Sure wonder at the stability - sorbate can be oxidized in water solution usually give a yellowish tint.

            I’d sure ask the supplier for stability data.

            https://pubs.acs.org/doi/abs/10.1021/jf60232a072

            • Aniela

              Member
              October 28, 2024 at 1:08 pm

              @PhilGeis Thank you, very much. I will check the colour and ask the supplier as you suggested. Now I’m going to read the article. Wishing you a good week🙂

  • echidna89

    Member
    October 19, 2024 at 6:27 am

    Ouch! I guess a stock solution isn’t an option.

    But what about the ratio? I’ve read that the usage for the combination of Na Benzoate and K Sorbate is 0.5% - 1.5%, but how much of which should be used at pH 5.5? Does 0.3% each of raw powder work?

    • PhilGeis

      Member
      October 19, 2024 at 11:35 am

      Use 2500 ppm of each

      • echidna89

        Member
        October 19, 2024 at 1:37 pm

        Thank you so much!

  • PhilGeis

    Member
    October 27, 2024 at 3:02 pm

    Sure!

    • This reply was modified 1 week, 4 days ago by  PhilGeis.

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