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Clay mask preservation
I recently made a batch of a clay mask (9% Kaolin/5% Bentonite/2.5% Charcoal/80% water). It is preserved with 1% Euxyl PE 9010 (Phenoxyethanol/Ethylhexylglycerin), which is added after the clays and charcoal are added. When filled in a tube, the tube begins to swell, and takes on a foul (cheesy) smell after about a week. One micro/yeast/mold test came back negative, but I sent this to a second lab testing with USP 61, and should have results tomorrow. The clays and charcoal are not irradiated, but have COA’s showing the CFU/g at <100.
In a lined drum, after about a week, you can detect the cheesy smell, and when shaken, the formula begins to bubble. In a tied closed drum liner, the bag will bloat.
Is Phenoxyethanol a poor preservative for this formula, or is it just being added to late in the process?
Is there a better preservative to use in a clay-based system such as Lincoside K?
Any thoughts or insight is greatly appreciated. THANK YOU!
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14 Replies
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Update: Micro test came back at 1.2 x 10^4 CFU. Clearly very high.
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You should start with irradiated clay and supplement with more water soluble preservatives - glycols, organic acids if pH works. What’s your water quality?
CoA <100cfu/ml ? How did they treat the stuff?
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Thanks @PhilGeis .
Water quality is R/O D/I.
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Micro quality?
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We sent in a sample from an earlier batch (prepared about a week earlier than the latest batch). That one came back at 1.2 x 10^4. The bentonite clay used in this batch did not have micro tests.
The recent batch used clays and charcoal that came with COA’s showing the micro load <100 cfu/g. The micro/yeast/mold test (USP 61) on the batch came back negative, but I believe it may have something to do with the incubation time. The batch in bulk has gained the cheese-like smell and is gassing, while it appears the product that is bottled takes more time to start taking on those effects.
Do you have any thoughts on this?
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Couple of recommendations. As @PhilGeis mentioned, start with irradiated clay. Second, add your PE9010 to the water phase and disperse well before adding the clays. PE9010 alone is not going to be sufficient to preserve a clay-based formula. Add-in Gluconolactone (and) Sodium Benzoate and perhaps some Pentylene Glycol and get your pH down to 4.5 or lower.
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Thanks @MarkBroussard .
Do you know of a good source of irradiated bentonite and kaolin?
Thanks for the preservative tips. Any thoughts about using Lincocide K (Methylchloroisothiazolinone (and) Methylisothiazolinone)?
Re the addition of pentylene glycol, will that essentially boost the gluconolactone/SB efficiency?
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No, sorry I don’t have a source of irradiated clays. I try to avoid making clay products … too messy.
Yes, Pentylene Glycol can boost preservatives.
I’ve never used Lincolcide K … that’s poison to my clients.
If you start with irradiated clay it makes you job much more simple. You need to have the preservatives well dispersed in the water phase prior to the addition of the clays. Otherwise water containing no preservative will fill the interstitial spaces of the clay and that’s where your contamination will start.
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Super helpful. Thanks!
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Masks are quasi leave on - not appropriate for isothiazoloinones and the CMIT is not stable > 7 pH
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Thank you, Phil!
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Update: I was able to use Vanatural Bentonite from Vanderbilt (higher cost than typical clays), which is a washed clay with a resulting low micro count. Also, by mixing the preservatives very well into the water phase, the product has passed micro/yeast/mold (<10C FU/g) after 90 days at 40ºC.
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Has it passed challenge?
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Didn’t try, and probably won’t run clay masks again.
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