Using black cocoa butter in emulsified scrubs, Vintage Blue asked: If I'm reading this right the preservative goes into the mix before I add the sugar. So I only calculate the preservative based on the weight of the oil mix not the oil and sugar? Wouldn't i be short on preservative if preservative weight is calculated on the final weight of the product? I just want to make sure that my product is well preserved before giving it as gifts to friends.
I'm so happy you want to preserve your scrubs! When I first starting writing this blog, every time I wrote about emulsified scrubs I'd have people not wanting to preserve them, so it makes my heart so happy to see how times have changed!
When I make emulsified scrubs, I tend to use 1% Phenonip, a broad spectrum preservative with a suggested usage rate of 0.25% to 1% in our products. In the end, every 100 gram batch of my sugar scrub base eventually becomes around 240 grams of emulsified scrub as I love to add loads of sugar. This means that I'm using about 0.42% preservative, which is well within the suggested usage rate!
In the formula below, there aren't any serious botanical ingredients that could cause problems down the road, like powdered extracts, aloe vera, or clay, so using 0.42% will work well. If you wanted to add more to the product just to be on the safe side, total up your base plus your sugar or salt, then add 1% of that. So for 240 grams of my favourite scrub, I'd add 2.4 grams total.
EMULSIFIED SUGAR SCRUB
10% emulsifying wax (e-wax, Polawax, or BTMS)
10% cetyl alcohol or stearic acid (5% cetyl and 5% stearic is very nice)
20% cocoa butter
56% oil - I'm using soy bean oil here
1% Vitamin E
2% fragrance or essential oil*
Check out the post on this topic on how to make it!
Water activity with sugar or salt scrubs
Debate: What kind of preservative should we be using with scrubs?