The two biggest ways you’ll know if your preservative is working are either the test of time (months and years), or a professional microbial challenge test (these typically run upwards of several hundred dollars per test, and still take some time get results).
For most home crafters who don’t intend to sell their products the cost of a professional test makes that option quite unappealing. So, we are left with time—and we all know that takes, well… time!
Here’s a few ways to increase the chances of our preservative succeeding:
- Choose a preservative with a good reputation (do some googling and look for experiences with it that aren’t from the manufacturer). This often means sticking to preservatives that have been around for a while. New preservatives come out all the time (especially more natural ones), but if you’re looking to to avoid doing the initial leg work to see if they work well, you’ll have to wait until somebody else does it.
- pH, maximum allowable temperature, required usage levels, etc. Make sure you’re working within those parameters.
- Use the maximum recommended amount, but no more.
- Follow good manufacturing practice—keep things clean as you work.
- Be aware of any more difficult to preserve ingredients in a formula; things like milk, clay, fresh fruits, etc. are really difficult to preserve. Keep in mind that more natural preservatives typically aren’t as strong as synthetic preservatives, so if you’re working with lots of harder to preserve ingredients you may want to choose a synthetic preservative instead of a natural one. You can purchase at-home microbial testing kits as well.
Found a new preservative that sounds promising, but you can’t find much on it? Try making a simple lotion using your new preservative, making sure you’re following the recommended usage rate, pH range, and any other pertinent requirements. Label it, and make note of your complete formula. Put the completed formula in a wide-mouthed jar and store it somewhere warm and bright (to encourage anything that might grow to grow faster). Wait, and see what happens. If it’s still looking good after three months, try making a more challenging lotion and add that to your experiment shelf.
If it’s still looking good after six months, shoot for a year. If it’s still looking good after a year, shoot for two. We can’t always see microbial spoilage, but if something still looks fine after a year, you can probably be reasonably confident it was ok at the six month mark. If you want even more information, get one of those at-home testing kits and test it every three months or so. See where it’s at!