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Salicylic Acid and Lactic Acid as preservatives!
Does this formula really need preservative??
I have read many places that acids are preservatives. And I make 2 formulas - 10% lactic acid gel and 2% Salicylic acid gel. So generally if the pH is below 4.5, sodium benzoate @0.5% should be enough.
But I already have acids, can I reduce % of sodium benzoate ??
Formula 1:
2% Salicylic acid gel
16 % propylene glycol
and pH 4.5Formula 2:
10% Lactic Acid
2% Glycerin
5% Propylene glycol
pH 3.8Any replies much appreciated!
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12 Replies
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Yes, neither Salicylic Acid or Lactic Acid are broad spectrum preservatives. You will get some preservation from the low pH and Sal Acid, but you still need to supplement this with a fungicide. Sodium Benzoate is cheap … the difference between 0.5% and 0.3% for instance is negligible as it relates to cost. So, why take a risk?
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Thanks a lot @MarkBroussard,
I am not trying to reduce the cost but the % of sodium benzoate for the purpose of lesser reaction on skin. A small % of our customers are getting reaction to PE 9010.
Phenethyl Alcohol is very similar to phenoxyethanol so guessing people who react to Phenoxyethanol react to Phenethy Alcohol.
Blend caprylyl glycol,EHG MOQ is 10 Kgs+ , But I can get them separately.
Not sure if blend Benzyl Alcohol, Ethylhexylglycerin will be less irritant that PE 9010.
Also Spectrastat not yet accessable. But also read that Caprylhydroxamic Acid can cause irritations(can be false info on internet)
Hope my search for less reactive preservative ends soon.
By the way I have Nipagaurd SCE (Sorbitan Caprylate, Propanediol, Benzoic Acid), but its turning my translucent gels turn opaque. If there is no other option then I will go for this. Because Benzoic acid is just 15% of whole.
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I see … can you get your hands on some pentylene glycol or 1,3-Propanediol? If so, try either one @ 3% + Acids. It would also be helpful if you could source some Dissolvine GL47 (Tetrasodium Glutamate Diacetate) a chelating agent that is a good preservative booster. None of these are irritating to the skin.
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@MarkBroussard
What is your opinion on GDL as chelating agent? -
Excellent … it’s the only chelator I ever use. I do also use Phytic Acid, but primarily to reduce pH although it does have functionality as a chelator
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@MarkBroussard
Ok, thanks! I was about to buy Sepimax Zen from The Formulary, and I saw they now sell GDL too. I will purchase that as well then! ☺ -
Some sources say that Gluconolactone and Glucono Delta Lactone is the same ingredient. I am not sure whether it’s true, but gluconolactone is marketed as a gentle exfoliant.
It’s the second ingredient in Lotion P50:
http://thewanderlustproject.com/2015/06/biologique-recherche-lotion-p50-review/#.XM3HkzBKjX4If it’s indeed the same ingredient and it has chelating properties (there is no EDTA in lotion p50) as well, it’s a gem.
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I don’t think you will need a preservative for both of your formulations. Try to test your formulations in a microbiology lab.
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QACS in Greece does quality and cheap USP51 testing.
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@Thota Potassium Sorbate might be another option, less irritant and works well at pH<6.5. It’s not a broad spectrum but might work in synergy with Sodium Benzoate at lower concentrations.
Additionally, like @em88 said, you might not even need preservatives. That’s because the pH of your final product will be really low (!!!), and that itself will reduce a lot the chances of bacteria/fungus proliferation. Combined with a couple mild preservatives, your gel will be just fine.
Look also at @ngarayeva001 example of P50 ingredients: acid, acid, acid, acid and more acid… some plant extracts to calm and reduce skin inflammation (from all the acid burning!!!)…then sodium benzoate and potassium sorbate as preservatives.
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I often see potassium sorbate/sodium benzoate blend in commercial acid peels. Usually as last ingredients.
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We have always had great success (backed up by testing) with Geogard ECT (Benzyl Alcohol (and) Salicylic Acid (and) Glycerin (and) Sorbic Acid) in those pH ranges.
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