Phenylpropanol EHG in cleansing formulas

Hello all,

I am trying to switch over to Phenylpropanol EHG as my preservative in shampoo and body wash formulations and have had mixed outcomes. In some batches, the result has been excellent - no change in formula viscosity, transparency, scent, etc. But in others, the product turns out cloudy and thinner viscosity and in one, it appeared to begin to cause separation. My usage rate has been 0.5% and I have tried adding it in two different sequences: mixed with one of the surfactants before heating (this after seeing the batch that started to separate) and at the end in the cool-down. I suspect that unfortunately the problem is interaction with different essential oils that make up the fragrance blends, but I would appreciate any insights or advice when it comes to using this preservative. I have had a hard time finding much detailed information about how to formulate with it, particularly in conjunction with surfactants.

FYI, the surfactant blend I use is CAPB, coco glucoside and SCI.

Thank you in advance for your help!

Comments

  • MarkBroussardMarkBroussard Member, Professional Chemist
    @KateLowen:

    You might have an easier time if you used Phenylpropanol + Pentylene Glycol + Propanediol.  There isn't a commercial blend with this exact combination, but you can purchase the ingredients separately and make your own blend.
    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
  • Thanks @MarkBroussard - so do you think the ethylhexylglycerin is the problem? In your experience is phenylpropanol compatible with most raw materials (e.g., essential oils)? Also, wondering if you have any comments on formulation techniques - it is listed as insoluble in water on the label (purchased from Making Cosmetics) which is why I have tried incorporating it in the surfactants first. Thanks again for your input!
  • MarkBroussardMarkBroussard Member, Professional Chemist
    Yes, Phenylpropanol is compatible with most ingredients.  If you mix it with Pentylene Glycol and Propanediol it will go into solution without appreciably clouding your formula (if it is clear).  I would add it as the last ingredient in your formulations.
    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
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