Once you embark on the path of hand made lotion making you will undoubtedly become familiar with a handful of popular preservatives in the DIY lotion world to prevent mold,fungus,yeast,and bacterial growth in your custom made products. Depending on what kind of lotion you make will influence the vulnerability that product has to be susceptible to bacterial growth over time. Product that contain water will eventually, over time, begin to cultivate microbes, while a product that contains no water is far more resilient to maintaining its integrity over a long spread of time. However, all products can develop growth, no matter how non-aqueous the recipe is formulated. Yes, even your solid lotion bars that contain ONLY hard oils can grow bacteria and mold. Lets look at the example below.
The recipe in this solid lotion bar contains no ingredients that are known to grow mold or bacteria. So why then, did colonies of mold spring forth after being left in storage for 8 months? Surprisingly enough, moisture alone is sufficient to encourage outbreaks of microbial growth. It is 100 percent possible to discover growth inside the cosmetic container of an anhydrous product.
The most common way moisture gets inside your lotion bottles is when you wash them for first time prep use. Yes, even when you use bleach, and even when you spritz the containers in rubbing alcohol, you must be completely thorough in making sure they dry on the inside before introducing the product. Even a small amount of water sitting between the product and inside of the container can become a potential nursery for animalitos.
In the images shown, one can see a transparent push top container that has been filled with a solid lotion. The colonies of growth are not through out the entire product, but have spread between the clear plastic and the product, and then across the top of the lotion where it had room to stretch out. This was likely due to a tiny bit of moisture left inside the tube after it was washed and the prematurely filled with lotion.
The product itself is not a friendly contact surface for microbial growth, so this did not happen quickly. It took several months for the mold to erupt, and only a few days to flourish.
Condensation, itself, is enough to encourage mold and bacteria. So, even if one is extra careful during the packaging process, eventually over time this situation can still be a reality. The long term storage environment is just as important to the integrity of your product as the conditions you control at the moment everything is put together. A cool dry climate is the best way to keep life at bay if you want to keep your lotions on the shelf before you sell it. The more humid and wet your storage space is, the faster you will need to replace your products.
Even the most professionally carefully packaged cosmetics occasionally fail a random test in the laboratory, which is one reason why the big companies – test, test, and test – all the time to keep close control over the quality of their products. You need to bear this in mind when you have your perfect lotion bottles and labels sitting perfectly on the shelves. Every few weeks crack open a bottle and give it a thorough check. Look for discoloration, spots, or odors that smell off in any way.
Remember: You may have been told that bacteria doesn’t grow in oil. So, how is it possible that you may discover mold or bacteria on the surface of your anhydrous products when you do a quality check after a few weeks?
When the tiniest amount of water condenses on the surface of your product due to high moisture or humidity, that water has no where to go. It will either eventually evaporate or just sit there, but it won’t absorb into the oil. This creates a potential miniature incubator for life, and even though it may bloom on the surface and not in the product, you don’t want anyone to ever discover something like this when they open your jars.
One way to identify this is to look closely at the edges at the top of the jar where the product meets the side of the jar. As you know, water tends to stick to surfaces and if there are tiny amounts of moisture it will cling to the sides on the surface. If this is where you identify any discoloration or disruption in your product, dispose of the affected product and make sure to get a suitable dehydrator into your stock room to keep the humidity down.
Do I really need a preservative in an anhydrous cosmetic?
If this is a product you want to sell, I wouldn’t recommend sorting out which of your products get a preservative and which do not. I would formulate a preservative into every recipe. There are so many variables you can’t control once your product has been packaged. For example, just because you have suitable storage conditions doesn’t meant your consumer does. What if he or she puts your pretty lotion bottle in their bathroom cupboard for three weeks in warm Miami, or in their shower and opens it when they’re ready? You have no control over the storage conditions once it leaves you possession. You’ll still want your product protected.