PhilGeis
Forum Replies Created
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Why do you want to autoclave?
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describe formula and package
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formula, pH, package
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The functional complaint would be infection rather than discomfort/irritation per se. Relevant microbial toxins would probably not have an effect topically so any perceived effect would need infection.
There are data in context of leave on context products and “normal” folks, but not much of anything for rinse off. In context of substantial immunocompromise, it was ~2 days. https://academic.oup.com/jid/article-abstract/158/3/655/2190564
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Are you sure you need a preservative for a shampoo bar? any idea the Aw?
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This is not a good idea. Water is the single most significant source of contamination in manufacturing, and we take great pains to maintain its microbiological and chemical purity. However, we don’t have this with most tap water that typically includes pseudomonads like Pseudomonas aeruginosa - one of the most common causes of cosmetic recalls.
This practice applied in hospitals has resulted ion the deaths of vulnerable folks. https://academic.oup.com/jid/article-abstract/158/3/655/2190564
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Preserve the powder - assume concerned re. mold growth under humidity. Parabens might be a better choice. This is something you prob try to determine on your own.
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Selenium is more effective than ZPT, partially because it deposits so well. So well, It doesn’t need help.
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Not all are sensitized - esp. at 3 ppm.
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Lower EDTA concentration to 0.1-0.2%
Suggest adding preservation vs fungi and Gram positive bacteria.
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I understand and don’t find that so useful. We’re working in dynamics of formulas, microbes and consumer use. There is some degree of consistency/predictability and it more Edisonian than formulaic - derives from efficacy in formulas in use. Most folks here don’t have the luxury of on-demand validated challenge testing and post consumer use survey so they’re best advised to reapply the basic stuff within identified safe in use ranges.
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So you don’t think I’m just blowing you off on this, here’s an example.
Challenge test revealed that benzoate consistently added a lot for preservation of surfactant products, esp. at pH (7.5) well above benzoic acid pKa. We’ve known this for many years before it was described and technically addressed in the literature.
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Glycols and phenoxy are weak vs fungi.
Highly recommended? Maybe the supplier but doubt anyone familiar with preservation would recommend glycerol caprylate
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I know some have found sorbic/benzoate good but it’s generally weak vs Gram negatives. Phenoxy+ is good v Gram negatives but weak vs Gram + and fungi. Ypu best off with a combination of the 2 - esp. benzoate and phenoxy+
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Neither is that great - Verastatil the the weakest - its pH range is prob driven by concerns for pH driven hydrolysis of its fairly-useless ester.
the 2-12 is absolute BS and should eliminate your consideration of that supplier.
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This reply was modified 4 months, 2 weeks ago by PhilGeis.
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This reply was modified 4 months, 2 weeks ago by
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consider benzoate, parabens.
can you describe product and formula?
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Me too. Too much “science” published in context of cosmetics is pure garbage. Consider the interpretation of ChatGPT that considers these vs the occasional good scientific report of folks who understand our technology.
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This reply was modified 3 months, 3 weeks ago by PhilGeis.
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This reply was modified 3 months, 3 weeks ago by
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I understand folks here are limited to the USP 51 based test that relies on microbes maintained in the lab each for many decades - one approaching 100 years. They are not representative of those that contaminate cosmetics. The test merely tells you the material has some antimicrobial efficacy, not that it has enough. Be assured that about every cosmetic product recalled passed the test, often with complete kill.
The significance of one additional in-use experience with a near term batch means nothing to the risk of lots of uses of just made and aged multiple product batches in the hands of all sorts of folks and their practices. You do not want to risk any of these folks within the boundaries of their intended and reasonably foreseeable misuse of any batch whenever they get it.
Few have the resources to develop/use a test validated to use or execute valid consumer testing. So please start with what should work, show the expected result in challenge.
Please understand safety - micro or chemical - is an affirmative process. Use a preservative systems that should and do work - not one that’s been dialed down to just pass or a couple of boosters.
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Maybe your seeing rancidification - that can be accelerated by some transition metals - esp. copper iron zinc tin reportedly via free radical formation. I know this is a problem the food and biodiesel folks experience. Maybe try some antioxidants but i know the chemistry isn’t that simple and some might make it worse. On the scalp makes it even ore complicated with the human and bug enzymes.
Curious - How did these folks get some much metal on their scalps?
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Apologies Richard - I have to comment as this practice, assuming consumer dilution, will most certainly have consumers using contaminated products. For most, this will at worst cause some mild folliculitis, but for immunocompromised folks (~30% of our population) the risk is serious as noted above.
No preservative will cover the risk of uncontrolled tap water. Recall our cosmetic preservatives are weak - they are not expected to achieve in a month the level of kill required of disinfectant in less than 10 minutes.
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Phytate works in many applications. I’d let the challenge data guide you in this.
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mention my name
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Here’s the guy -
Gerald B. Kasting
Professor Emeritus of Pharmaceutics and Cosmetic Science
James L. Winkle College of Pharmacy
University of Cincinnati
513-484-6474
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I’ll make some calls.
btw - it’s :”Phil”.
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Good point with the permeation enhancement. Whatever preservative goes on skin will go into tissue. To that, there are very little data for any preservative with the exception of paraben. Parabens do permeate and are impacted by esterases in skin and tissue. A CDC study - a good one as in not Darbre quality - found parabens at exceedingly low levels in urine of typical men. Cosmetic industry generated a lot of sound data that was not published for parabens uptake and excretion that defended typical use. I’m not toxicologist enough to address the concern with assurance but gut feel would look to preservatives used for injectables. I could hook you up with someone if you want.
I’d stay away from the marketed combinations. They’re organized for unique marketing positioning if not patent protection, claim unjustified broad spectrum and wide pH coverage and presume safety of the combination rather than confirm. In context of greatly enhanced permeation, I’d trust none.