Challenge Testing or Preservative Efficacy Testing
This is the most rigorous test to determine whether your preservative is working. It involves introducing known bacteria (E. Coli, Pseudomonas, and Staph) and Fungi (Aspergillus, Candida) into your product. Plate counts are done at various times over a months period afterward. If the preservative is working, counts will decrease within 2 weeks and not increase again after that. We no longer offer this test and recommend Cosmetic Test Labs at MicroChemLabs.
Common Usage Test
This test is an alternative to the Challenge Test that is recommended to home crafters who are not widely marketing their product. It is much less quantitative and rigorous than the challenge test but still gives useful information to fit a home crafters budget. To do this, first send a product in for testing.  If these counts come out zero to low it assures that you are starting with good GMP (good manufacturing practices) and your product is without contamination. Now, take a second sample from that batch and use and abuse it for several days. Make sure you stick  your dirty fingers into it and leave it open – enough abuse that you know you are getting bacteria and fungus in the product.  Don’t hold back. Send this sample in for testing after a week or two. This second test will tell you how your product holds up to that insult and gives an idea how effective your preservative is.  The counts for the second testing should be as low as the first testing.  The cost for this would be that for two APC and fungal/yeast tests.
Shelf Life of a preservative is a difficult thing to assess and can really only be done in real time. You might try having your products tested ever 3-6 months to estimate a shelf life or determine how long their preservative works.

Stability testing is separate and tests whether your emulsion will stay together. Stability is ‘accelerated’ with increased heat to simulate time.

To send a sample, download and print the request form by clicking the button below and send that in with your sample. Payment can be made by enclosed check or by Paypal. Go to this page for Paypal.


Non Disclosure.

Information that you share with us for any reason remains confidential and is not shared outside of Sagescript Institute unless specifically requested by you.  Your test results remain in your ownership.

You will need adobe reader to download the form, please click here to download it for free.

Although it is ideal to test every batch, this is impossible for many small crafters. My suggestion is to have initial testing done to make sure your product is well preserved and then do periodic testing (random) to make sure your GMP is good.

Additional services are available on a consultation basis. These might include gram stain, challenge testing, Mean Inhibitory Concentration (MIC). Pricing for these will vary depending upon details.

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Here is what the FDA guidelines say about bacteria in cosmetic products:

“Cosmetic products are not expected to be aseptic; however, they must be completely free of high-virulence microbial pathogens, and the total number of aerobic microorganisms per gram must be low. Since there are no widely acceptable standards for numbers, temporary guidelines are used instead. For eye-area products, counts should not be greater than 500 colony forming units (CFU)/g; for non-eye-area products, counts should not be greater than 1000 CFU/g. The presence of pathogens would be particularly important in evaluating as unacceptable a cosmetic with a marginally acceptable count, e.g., 400 CFU/g for an eye-area product. Pathogens or opportunistic pathogens whose incidence would be of particular concern, especially in eye-area cosmetic products, include S. aureus, Streptococcus pyogenes, P. aeruginosa and other species, and Klebsiella pneumoniae. Some microbes normally regarded as nonpathogenic may be opportunistically pathogenic, e.g., in wounds.”
The EU recommendations are similar.

You can read more on my blog post here.
Need Testing other than Microbiology? Try Cosmetic Test Labs at MicroChemLab.

“What is essential is invisible to the eye…”
– Antoine de Saint-Exupéry, in The Little Prince