Home Cosmetic Science Talk Formulating Preservative failing PET - Help

  • Preservative failing PET - Help

    Posted by Paddym on February 7, 2022 at 12:54 am

    Hey everybody. We are currently working with a lab to produce a range of men’s hair styling products (waxes, clays, pomades etc.). We recently got word that our ‘clay’ failed PET. Here is an ingredients list to give you an idea of what is in the formula.


    Kaolin Clay
    NZ Glacial Clay
    Candelilla Wax
    PEG-40 HCO
    Cetearyl Alcohol
    Shea Butter
    Grapeseed Oil
    Polysorbate 20
    VP/VA Copolymer

    The only perservative in there is currently Phenoxy, and the head chemist thinks that we would be better to change that to increase efficacy. We head from the PET testing that the product initially did well, passing phase one, but once bacteria was introduced into the product, it failed. The chemist at the lab is suggesting moving to either paraben or dmdm hydantoin.. neither I am wholey comfortable with. I would prefer to continue down the Phenoxy route, and would be keen to hear what could be added to it to beef up it’s efficacy… I hear EDTA can sometimes be effective. Any advise I will pass onto the head chemist. The only ingredient that you probably aren’t familiar with is NZ glacial clay, which meets the labs standard in terms of bug count, coming in at 50 (I’m not sure what the scale is) with the limit being 100. Keen to hear your thoughts.


    PhilGeis replied 2 years, 4 months ago 4 Members · 4 Replies
  • 4 Replies
  • Graillotion

    February 7, 2022 at 1:00 am

    No mention of pH?

    Are your clay’s irradiated? 

    Do you have a chelate?  (I’ll be interested to hear what the chemist have to say…with clays and chelates.)


    (Sounds like your chemist already knows how to solve the problem….except I would have but an ‘and’ between them, not a ‘or’.)  :) 

  • Paddym

    February 7, 2022 at 1:08 am

    Kaolin is irradiated, glacial clay isn’t. Not sure about a chelate or the pH. I can ask

  • Abdullah

    February 7, 2022 at 1:44 am

    EDTA always help.

    If you can share the result of pet test we will know what is the weakness in your product and suggest you a preservative that is effective for that. 

    Usually a blend of preservatives is used because one preservative will be overkill for one organism and weak for another

  • PhilGeis

    February 7, 2022 at 12:15 pm

    Clay is hard to preserve and chelants do poorly with it.  DMDM hydantoin with parabens or an organic acid (if pH permits) would be a reasonable try.

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