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Preservative effectiveness
Hello,
First of all, thank you to Perry and all who make this forum happen. It is so great to have this resource.I was wondering about the effectiveness of a preservative in a shower scrub. If the formula with preservative passes the microbial tests, will the preservative continue to perform during use with water added from wet fingers in the shower?Thanks! -
6 Replies
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That is specifically what a challenge test/preservative efficacy test determines. The test lab deliberately introduces microbes, then tests to see how quickly they die.
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But the question wasn’t just about fingers inoculating the jar with microbes. The question is, could fingers bring in enough water to make, even locally on top of the rest of the product, the preservative too dilute to work?
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That depends on how much water is introduced. Theoretically, yes you could dilute your product with enough water that the preservative is not effective enough. But in practice, if you pass a PET then you’ll probably be ok. People don’t introduce that much water into their formulas.
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This actually sounds like more of a poor packaging decision than a preservation issue. If you are using a product designed for application in the shower … why is it that you are using a container that would allow any, yet that much, water to get introduced into the product during use?
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I’d suggest an in-use study, then. Have someone, or several people, use a sample of the product each in the shower until it’s halfway used up - then run a PET on the remaining material. It’s the only way to tell for sure.
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@MarkBroussard
There are no many packaging options for shower scrubs. Most shower scrubs contain sugar-or other big particles-so it is not something you can put in a bottle with a pump or in a standard tube.
I’ve seen tubes with a big orifice that eventually could be used for a scrub, but it doesn’t work for scrubs with a thick consistency. Also, these are not easy to find.
So at the end of the day, most people, including some popular brands, end up using jars.
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