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Best preservative for pH > 7 liquid mud / clay face masks?
Most preservatives work best in pH’s lower than 6, making the choice of preservative for liquid mud masks - which are extremely prone to mold/fungal growth, difficult.
So far I’ve used Liquid Germall Plus (Propylene Glycol (and) Diazolidinyl Urea (and) Iodopropynyl Butylcarbamate) at 0.4% in conjunction with Leucidal Liquid SF (Lactobacillis Ferment) at 2% and it has stood up to basic microbial testing, but there could be safer options out there. Let me know if you have any other recommendations for something that’s gentle, not parabenes (customer base issue) and effective.American Pharmaceutil Review wrote and extensive whitepaper on preservatives: http://www.americanpharmaceuticalreview.com/Featured-Articles/38885-Antimicrobial-Preservatives-Part-Two-Choosing-a-Preservative/
And Making Skincare (hi!) wrote an extensive, although not as rigerous review of 27 common preservatives here: http://www.makingskincare.com/preservatives/
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7 Replies
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It’s advisable first, to sterilize the mud with gamma rays.
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if you’ve got large amounts of clay in your formula you’ll need something substantially water soluble (i.e. not phenoxyethanol) or else it’ll adsorb onto the clay and be rendered ineffective; the only time I’ve ever seen Euxyl PE9010 fail a challenge test was in a formula with 20% clay in it
Suttocide A, sodium hydroxymethylglycinate, is supposed to be effective at high pH, though I’ve not used it myself
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Suttocide A … I would stay away from it … serious eye irritation from the fumes and it has a nasty smell.
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You might try acidifying your concoction to pH below 6, if that does not create conflicts with other ingredients, to give you a wider selection of Preservative options.
Adding ethylhexylglycerin at 1% (its max solubility in water) generally will boost the efficacy of some Preservatives up to pH 9 or so.
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Could you also replace the Leucidal with Polyaminopropyl Biguanide?
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Thanks @MarkBroussard
Do you know anything about how Ethylhexylglycerin compares to Diazolidinyl Urea (and) Iodopropynyl Butylcarbamate or were you thinking of using the together?
Any obvious disadvantages of reducing pH to 6? I’m using 5-10% calcium carbonate so It might not be practically viable to do so.@EliseCortes
Not really looking to replace it, rather add another preservative. -
Ethylhexylglycerin is a preservative booster … it’s mechanism of action is to weaken the micorbial cell wall making it easier for the actual preservative to penetrate the cell. So, you might go with a blend of Benzyl Alcohol/Ethylhexylglycerin or Phenoxyethano/Ethylhexylglycerin.
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