Green or safer preservative

Hi everyone,

We want to use another preservative in our liquid soap formulations because the one we use now has several concerns with the levels of skin allergies (we use Kathnon CG, a mixture of methylisothiazolinone and chloromethylisothiazolinone). I want to know if you have some ideas for a grenner/safer alternative to preserve our formulation of pathogenic bacteria and fungi (sodium benzoate, potassium sorbate, etc...). We don't want to use paraben (even though we know that their safety is questionable).

Thanks and have a nice day!

Comments

  • With pH <= 4.5, potassium sorbate or sodium benzoate work fine in my experience.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • Thanks for your answer. 

    Does a pH of 4.5 for a liquid hand soap is not too low? Do you think sodium benzoate will work well also in the 5-5.5 pH range?
  • Check this out. Should prove extremely helpful.

    http://www.makingskincare.com/preservatives/



  • MarkBroussardMarkBroussard Member, Professional Chemist
    The preservative that will meet your criteria will first depend on whether your final formulation is above or below pH 6.0. You will have more green options at pH below 6.0 than above. If above pH 6.0, phenoxyethanol/ethylhexylglycerin or benzyl alcohol/ethylhexylglycerin would be feasible options.

    What is your final pH?
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
  • @ laskedbetter: Thanks for the link I will certainly read it

    @MarkBroussard : My final pH is between 6-6.4. But surely I can lower it a little bit to be ine the range of 5.5-6... Benzyl alcohol/ethylhexylglycerin mix sounds interresting to me. In which ratio these products should be present and at which concentration in the finish product?
  • MarkBroussardMarkBroussard Member, Professional Chemist
    Ok, if your final pH is above 6.0, then you can use Benzyl Alcohol/Ethylhexylglycerin at 1.0%  (it's in the Euxyl series from Schuelke & Mayr).

    If you are buying the Benzoyl Alcohol and Ethylhexylglycerin separately, try 0.5% to 0.8% Benzoyl Alcohol and 1.0% EHG.  Even better, use an EHG/Caprylyl Glycol blend.

    Are you also using any glycols to bind free-water?  If not, add 6% 1,3-propanediol or 2% glycerin.
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
  • Bill_TogeBill_Toge Member, Professional Chemist
    @xenon126 pH 4.5 is fine for a hand soap, in fact if you use salicylic acid you need a pH between 3.5 and 4.0 for it to show any antimicrobial activity 

    anything below pH 3 is classified as a skin irritant unless you have positive proof to the contrary, so you'll want keep your pH above 3

    @MarkBroussard you'll need to use a LOT more glycol than that (30-40% or more) for it to have any significant effect on water activity

    propylene glycol does have a preservative effect at 10-15% w/w, but this is due to its properties as a 1,2-diol rather than its effect on water activity
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • MarkBroussardMarkBroussard Member, Professional Chemist
    @Bill_Toge

    The glycols are recommended to be included as preservative boosters, not a preservatives themselves, so the levels I recommended are appropriate.
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
  • Recently, I've come across two vendors selling toners and there are no preservatives listed.  One was nothing but rosemary hydrosol and the latest is aloe based.  I inquired about the aloe based product and the first response was that they needed no preservative as the product is not water based.  I inquired further and this was the response, "The aloe we source is  fractionally distilled we have certificate of analysis on each batch received.  We had previously used hydrosols in the tonic with food based preservatives."  

    The complete ingredients as listed are:
    100% fractionally distilled Aloe Barbadensis Miller (Aloe Vera Leaf), organic glycerin (vegetable glycerin, organic lavendula hybrida or rosa damascena.

    Can the glycerin alone preserve this?  Or, would you need to know the percentage of glycerin?  I would think enough glycerin to preserve it would make the skin feel very sticky.

    Thanks in advance for your insight.  I always am trying to understand preservation methods to ensure anything I create is safe.

  • MarkBroussardMarkBroussard Member, Professional Chemist
    No, these products are essentially unpreserved.  "Fractionally Distilled" is simply the method by which the aloe fraction was extracted from the bulk mother liquor.  You're right about glycerin.
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details www.desertinbloomcosmeticslab.com
  • PerryPerry Administrator, Professional Chemist
    Of course, the ingredients could have preservatives in them and the company is just choosing to ignore putting that on their labels.  They could be willfully ignorant or doing that on purpose.  But more likely, the products will become contaminated and dangerous to use over time.
  • Thank you, @MarkBroussard and @Perry.  Nice to know I am learning and can trust my judgement a little.  

    @MarkBroussard, that is exactly what my thoughts were about the "fractionally distilled", simply the extraction method that had nothing to do with preservation or need to preserve.  I had also inquired about testing and the question was ignored twice.  

    So, how do vendors get away with improperly (or not bothering to) preserving products?  A large international cosmetic retailer is carrying an item from this line.  Not the toner in question, an anhydrous lip product, but that is going to give the vendor huge exposure!  I don't understand that.  

  • PerryPerry Administrator, Professional Chemist
    Ah, well, anhydrous products usually don't require preservation.  It's advisable to use a preservative in case there is some residual moisture left on the product but lot's of companies don't preserve their anhydrous products.
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