Because I make things that contain water, like mists and lotions, I use preservatives. As you may have picked up on in my blog posts, I highly encourage you to also use a good broad spectrum preservative. If you balk at the thought of it, please understand that a tiny bit of preservative in your final product is much better than the risk of invisible bacteria or fungi all throughout it. Also, if you’ve ever had the perfect lotion you worked hard on grow mold after just a few days, you’ll quickly become a fan of a good preservative.
There are a lot of broad spectrum preservatives readily available from DIY suppliers. My favorite place to purchase preservatives is Lotion crafters. Here are a few of the preservatives available for home use:
Liquid Germall Plus
Optiphen series (can destabilize emulsions)
Phenonip (contains parabens)
Leucidal (not truly a broad spectrum preservative)
NataPres (not truly a broad spectrum preservative)
The following are sometimes sold in the “preservatives” section but they are not preservatives, rather antioxidants. They will extend the shelf life of your oils and butters in anhydrous products but offer no protection against mold or bacteria in items that contain water.
Grapefruit seed extract
Some preservatives are safer than others, some are more effective than others, and I highly encourage you to research them all and find the ones that work for you. Skin Deep is a fantastic place to research the safety of different preservatives (and all ingredients, really). I also encourage you to read everything about the preservative from the supplier to determine if it will work for you. Effective pH range and solubility are important things to consider.
NeoDefend™, NataPres™, and GeoGard ECT™ are going to be the safest looking broad spectrum preservatives you’ll research, but unfortunately, from my reading, they aren’t great choices. This page is a fantastic resource to learn more. NeoDefend™ cannot be used with vitamin C and the final product must have a pH below 5. NataPres™ is not a true broad spectrum preservative and requires a secondary preservative. For the home DIY maker, these preservatives are difficult to use reliably.
I use Liquid Germall Plus for my everyday concoctions and Optiphen ND for items that are mostly water (or essentially fluid with no oil except essential oils). Liquid Germall Plus “may” cover water only items; Optiphen ND definitely does. I don’t like mold in bottles of bug spray or other stuff I’ve made, so I invested in the Optiphen ND. Both are water soluble, effective in small amounts, and have a broad effective pH range. They are not easily accidentally deactivated. You are unlikely to need to test the pH or adjust it. The usage rate is 0.1–0.5% for Liquid Germall Plus or 0.3-1.2% for Optiphen ND, although I would recommend erring on the higher of things for home use, since our kitchens are far from sterile. I used to use plain Optiphen, but it kept breaking my emulsions and I finally had enough. Also, despite the fact that it contains paraben, I’ve started using Phenonip in oil only preparations like sugar scrubs, which can grow mold in moist and steamy bath rooms and from having wet fingers scooped through them. The benefits outweigh the potential risks.
How much do I need to use?
Each preservative will have a different recommend usage rate, which you can get from your supplier.
Let’s say your preservative should be used at 1%; if your recipe contains 4 oz of ingredients, that’s approximately .04 oz of preservative. That’s not 100% accurate as 1% of 4.04oz (original recipe + weight of the preservative) will be just over .04 oz but with the small batches we’re working in the the accuracy level of the scales we’ve got at home, I consider it to be close enough. Figure out how much your recipe weighs. Either add up the weights of all the ingredients or weigh the final product. It’s really that simple.