Home Cosmetic Science Talk Formulating Clay mask preservation

  • Clay mask preservation

    Posted by CGN on November 27, 2023 at 7:41 pm

    I recently made a batch of a clay mask (9% Kaolin/5% Bentonite/2.5% Charcoal/80% water). It is preserved with 1% Euxyl PE 9010 (Phenoxyethanol/Ethylhexylglycerin), which is added after the clays and charcoal are added. When filled in a tube, the tube begins to swell, and takes on a foul (cheesy) smell after about a week. One micro/yeast/mold test came back negative, but I sent this to a second lab testing with USP 61, and should have results tomorrow. The clays and charcoal are not irradiated, but have COA’s showing the CFU/g at <100.

    In a lined drum, after about a week, you can detect the cheesy smell, and when shaken, the formula begins to bubble. In a tied closed drum liner, the bag will bloat.

    Is Phenoxyethanol a poor preservative for this formula, or is it just being added to late in the process?

    Is there a better preservative to use in a clay-based system such as Lincoside K?

    Any thoughts or insight is greatly appreciated. THANK YOU!

    CGN replied 1 month, 2 weeks ago 3 Members · 14 Replies
  • 14 Replies
  • CGN

    Member
    November 28, 2023 at 12:04 am

    Update: Micro test came back at 1.2 x 10^4 CFU. Clearly very high.

    • This reply was modified 6 months, 3 weeks ago by  CGN.
  • PhilGeis

    Member
    November 28, 2023 at 5:56 am

    You should start with irradiated clay and supplement with more water soluble preservatives - glycols, organic acids if pH works. What’s your water quality?

    CoA <100cfu/ml ? How did they treat the stuff?

    • CGN

      Member
      November 28, 2023 at 6:23 pm

      Thanks @PhilGeis .

      Water quality is R/O D/I.

      • PhilGeis

        Member
        November 29, 2023 at 6:07 am

        Micro quality?

        • This reply was modified 6 months, 3 weeks ago by  PhilGeis.
        • CGN

          Member
          December 1, 2023 at 11:16 am

          We sent in a sample from an earlier batch (prepared about a week earlier than the latest batch). That one came back at 1.2 x 10^4. The bentonite clay used in this batch did not have micro tests.

          The recent batch used clays and charcoal that came with COA’s showing the micro load <100 cfu/g. The micro/yeast/mold test (USP 61) on the batch came back negative, but I believe it may have something to do with the incubation time. The batch in bulk has gained the cheese-like smell and is gassing, while it appears the product that is bottled takes more time to start taking on those effects.

          Do you have any thoughts on this?

  • MarkBroussard

    Member
    November 28, 2023 at 6:25 am

    @CGN

    Couple of recommendations. As @PhilGeis mentioned, start with irradiated clay. Second, add your PE9010 to the water phase and disperse well before adding the clays. PE9010 alone is not going to be sufficient to preserve a clay-based formula. Add-in Gluconolactone (and) Sodium Benzoate and perhaps some Pentylene Glycol and get your pH down to 4.5 or lower.

    • CGN

      Member
      November 28, 2023 at 6:25 pm

      Thanks @MarkBroussard .

      Do you know of a good source of irradiated bentonite and kaolin?

      Thanks for the preservative tips. Any thoughts about using Lincocide K (Methylchloroisothiazolinone (and) Methylisothiazolinone)?

      Re the addition of pentylene glycol, will that essentially boost the gluconolactone/SB efficiency?

      • This reply was modified 6 months, 3 weeks ago by  CGN.
  • MarkBroussard

    Member
    November 28, 2023 at 6:34 pm

    @CGN

    No, sorry I don’t have a source of irradiated clays. I try to avoid making clay products … too messy.

    Yes, Pentylene Glycol can boost preservatives.

    I’ve never used Lincolcide K … that’s poison to my clients.

    If you start with irradiated clay it makes you job much more simple. You need to have the preservatives well dispersed in the water phase prior to the addition of the clays. Otherwise water containing no preservative will fill the interstitial spaces of the clay and that’s where your contamination will start.

    • CGN

      Member
      November 28, 2023 at 6:43 pm

      Super helpful. Thanks!

  • PhilGeis

    Member
    December 1, 2023 at 12:39 pm

    Masks are quasi leave on - not appropriate for isothiazoloinones and the CMIT is not stable > 7 pH

    • CGN

      Member
      December 1, 2023 at 3:31 pm

      Thank you, Phil!

  • CGN

    Member
    May 9, 2024 at 11:40 am

    Update: I was able to use Vanatural Bentonite from Vanderbilt (higher cost than typical clays), which is a washed clay with a resulting low micro count. Also, by mixing the preservatives very well into the water phase, the product has passed micro/yeast/mold (<10C FU/g) after 90 days at 40ºC.

    • PhilGeis

      Member
      May 9, 2024 at 12:09 pm

      Has it passed challenge?

      • CGN

        Member
        May 9, 2024 at 2:04 pm

        Didn’t try, and probably won’t run clay masks again.

Log in to reply.