whipped butter post I wrote about yesterday, Roxine asked in August 2011: If I wanted to add preservatives to this, do I add the recommended usage amount based on the total product weight. So say, .05% of the butter made with the oils and FO? Or is the percentage of preservative I use a part of the total 100% of the final product, so i would take .5% off somewhere else, like in my oils. I hope I don't sound too stupid here...
No, you don't sound stupid! The only stupid question is the one never asked! And when it comes to preservatives, you can never be too careful!
My short answer is this - you don't need to use preservatives in an anhydrous product unless you fear water might come in contact with it. For something like a sugar scrub, you want a preservative. For a whipped butter that won't be coming into contact with water, you don't really need it. Having said that, if you want to add one, then add one!
If you do want to use a preservative, you need to choose one that is oil soluble. Phenonip would work - you'd use it in the heated oil phase of your product - as would Liquipar Oil. If you want to use Phenonip, you'd use it at 0.5% to 1% as you heat your butters and oils. If you want to use Liquipar Oil, use it at 0.4% to 0.8% when the product is at less than 80˚C (which means pretty much any point with a whipped butter).
So let's say you want to use Phenonip in your whipped butter...here's a sample recipe...
WHIPPED SHEA BUTTER WITH PRESERVATIVES
78.5% shea butter (I use ultra refined)
19% fractionated coconut oil (or any other oil)
0.5% Vitamin E (to retard rancidity, optional)
1% fragrance or essential oil
Weigh your shea butter, oil, and Phenonip in a heat proof container and put into your double boiler to heat until melted. Remove and leave to cool (I put it in the freezer, but that's just my preference). When cooled, add your Vitamin E and fragrance/essential oil and whip until it reaches the whippiness level you like.
Having said all of this, you don't really need to preserve your anhydrous products due to something called water activity. And considering how freakazoid people get about parabens and considering that parabens are the only preservatives suitable for anhydrous products, you might find it easier not to preserve them!
As an addendum to this question: If you're using preservatives, use them at the suggested levels for the total amount of this recipe. So if you have a lotion recipe that totals 100%, you would use 0.5% liquid Germall Plus and remove 0.5% from the water phase, so your recipe always totals 100%. (We always remove additional ingredients from the water phase - click here for the reasoning behind that!) Your recipe should always total 100%. If you're making a lotion, shampoo, conditioner, or any other product we could make, use the preservative at the suggested usage rate in the suggested phase and make sure your product totals 100%.
HOWEVER this can change with something like a sugar or salt scrub. For instance, when I make a sugar scrub, I make the base, then add the scrubby bits. I base my preservative amount on the amount in the base and I don't tend to take into account the salt or sugar. So I'd make up my base of oils, butters, and so on and use 1% Phenonip in the heated stage. I would add my salt or sugar at the rate I like - generally 140% for sugar, although I will go higher - and not add extra preservative to compensate for the scrubbies.