I recently started formulating cosmetic products this year. I had purchased the microbial test kit from Making Cosmetics and proceeded to test two of my formulations - a body lotion & a face lotion. I did not use an incubator for the testing, I left the vials at room temperature for a duration of time starting 6/29/21. Unfortunately, the natural temperature in my house fluctuates, and there is generally a high level of humidity each day, so the temperatures / environment were not as consistent as an incubator.
So, after the first couple of weeks, there were no changes to either side of the test sticks. I left the vials for a couple more weeks, and then today is the first time I looked at them, and to my surprise, the face lotion vial has darkish gray mold? growing on the rose agar side. This is the only difference I see in both of the vial samples.
My question is - does this mean my preservative fails the test? Or is this expected for how long I let them sit? Was it normal that there were no changes whatsoever in either vial for the first couple of weeks? Are these tests inaccurate due to the environment that I left them in?
I am currently using 2% phytocide aspen bark extract as my preservative system in both of those formulations.
Thanks for all feedback!