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Preservative mix in shampoo
Hello everyone!
I developed a shampoo with the following ingredients
Water, Sles, Capb, Peg - 4 Rapeseedamide, Caprilic Capric glycerides, aloe Vera, olive oil , fragrance, natural extract of rosemary, panthenol
,polyquaternium 10, polyquaternium 7 , EDTA
Total active surfactant percentage is 15% with Sles being dominant.I use the following preservative mix
Phenoxyethanol 0,8%
Benzyl Alcohol 0,35%
Sodium benzoate 0,6%
Potassium Sorbate 0,6%
Dmdm Hydrantoin 0,3%1. Do you consider the mix too potent?I need the product to have a shelf life of 2 years and don’t want to boil my deionized water beforehand in order to sterilize it.
2. Is there a probable interaction / reaction between the ingredients of the formula and the preservatives?
Thank you!
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14 Replies
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I can only speak for myself, but in my opinion that is way too much. I only use one of those preservatives in our sulphate-free shampoo, potassium sorbate, at 0.5%, and the shelf life has been at least 6 months in a sample that we used to open and allow customers to smell the aroma.
Also note that your surfactants themselves may or may not already contain preservatives. -
Good point @belassi. My CAPB is 40% so no preservative, Sles 70%, and rapeseedamide 93% both purchased from Kao
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Another Kao customer eh! Try the Akypo RLM 45 CA and Foam RL 40.
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with phenoxyethanol and benzyl alcohol you risk them separating, since both have low solubility, even in surfactant systemspotassium sorbate is most effective below pH 6, but causes terrible yellowing/browning in liquid productsin my view, DMDMH and sodium benzoate are the only ones which are efficacious and practical for a shampoo; and you’ll have to keep your pH below 5 for the sodium benzoate to be effective -
Yeah, 0.3% DMDM Hydantoin is plenty. We used 0.2% as the only preservative for the shampoo I used to work on (VO5). Our stability was good for over a year.
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Bill: potassium sorbate is most effective below pH 6, but causes terrible yellowing/browning in liquid products
Aha. So this is why a small test bottle of our shampoo turned brown after about 8 months or so? I had assumed the preservative had failed. It still smelled OK. -
Hmmm I thought that the browing was caused due to the vanillin content of my fragrance. Very interesting point @Bill_toge.
So @Perry you consider the rest preservs unnessessary? Should I run the challenge test only with DMDM Hydrantoin?Even if i don’t sterilize the deionised water?Thank you all for the comments -
We tried 0.3% DMDMHydantoin along with 0.01% kathon CG in our shampoo system it worked well.
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@toge thanks for the information.could you please sent the free site links for the same as i am not able to get these articles
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The interesting thing for me is that I switched from using sodium benzoate to potassium sorbate because I’d heard that the benzoate could irritate. Did I make the wrong decision?
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Hey, In My opinion, Sodium benzoate works below ph 5. So good to go with Methylisothiazolinone & Methylchloroisothiazolinone with 0.01%.
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For shampoo - use isothiazolinone (as suggested), Na benzoate (2500 ppm) and EDTA (1000 ppm). Anionic surfactants raise the effective pKa for Benzoate.
Vs. isothiazolinone, Phenoxy is not as good but DMDM Hydantoin (2500 ppm) would be a replacement..
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I understand some may not be familiar with antimicrobial efficacy of benzoate/benzoic acid at near neutral pH. Here’s a ref - https://www.sofw.com/en/sofw-journal/articles-en/47-home-care/1703-enhancing-antimicrobial-efficacy-of-sodium-benzoate
and You’ll find it with isothiazolinones in many mass market shampoos.
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