Is this formulation likely self-preserving?

I understand that any preparation with a pH less than 4 presents a challenging environment for microbes to grow in.

On that basis, if I have an AHA BHA toner with a pH of 3.5/3.6 and 10% ethanol, is this recipe most likely self-preserving?  

Thank you.

Comments

  • MarkBroussardMarkBroussard Member, Professional Chemist
    @suswang8

    It could be, by why take the chance by not adding a preservative?
    Chemist/Microbiologist formulating in the Organic & Naturals & Clean Beauty arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program/Clean At Sephora/Credo Clean guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
  • PhilGeisPhilGeis Member, Professional formulator
    Unlikely.
  • @PhilGeis
    why would you say unlikely?
  • PerryPerry Administrator, Professional Chemist
    Because there are things that can grow at that pH
    Because 10% ethanol is not preserving
    Because you don’t know how much microbial exposure the product will experience 
    Because you don’t know the storage & use conditions of the product
    Because lots of reasons.

    why not just add a preservative?
  • PhilGeisPhilGeis Member, Professional formulator
    As Perry said.  

  • Bill_TogeBill_Toge Member, Professional Chemist
    it depends on titratable acidity more than the pH itself; from my experience, the lowest level of acidity at which I've observed consistent self-preservation is around 25-30 mg KOH/g
    over several years we made dozens and dozens of batches of this product, and others with  higher acidites, and never had microbial growth in a single one
    UK based cosmetic chemist with 13 years' experience at the bench. I've worked with pretty much everything apart from pressed powders, soap, solid lipstick and aerosols.
  • MarkBroussardMarkBroussard Member, Professional Chemist
    @suswang8

    The only way to know for certain is to test your product.  Not knowing what else is in it ... I am assuming you are using a chelating agent?
    Chemist/Microbiologist formulating in the Organic & Naturals & Clean Beauty arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program/Clean At Sephora/Credo Clean guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
  • PhilGeisPhilGeis Member, Professional formulator
    Testing is not enough.  The USP51-types whatever the pass/fail are not validated to anything.
    Every recalled product passed the test.
    Folks should design a preservative system that should work and confirm it passes. 
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