Teach Soap

I use Optiphen in my lotions, but not in my smaller (4 oz) scrubs and creams, and haven't had any problems with out one. I just tell people to use it within 2 months. Now, I'm going to start offering 8 oz sizes and am concerned that this larger size won't hold up well without one (especially the things used in the tub).

My question is when I figure the amount based on weight, I get drastically different amounts of preservatives needed for 8 oz of each. For example, an 8 oz jar of my salt scrub weights 15 ounces and 8 oz of my salt scrub weighs only 6.4. So I'd need a whole lot more Optiphen for the salt scrub simply because it's just salt and oil, and doesn't contain Shea like my sugar scrub.

Is that right? Am I supposed to figure based on the total weight, or just the weight of the oils/butters?

Phenonip is normally used at 0.5%-1.0%. I would use a preservative in all of them. You won't be able to guarantee that the scrub is safe if someone gets water in it; no matter what size. You measure out the preservative according to the total weight of your ingredients. When you make a batch, add it to the whole batch. I would start at 0.5%
So for a 16 ozs. of scrub, you would need 0.08 oz. For such a small amount, you would need a scale that measures to 1/100 of a gram.

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Irena
Closed minds are like faulty parachutes; they refuse to open.