Q&A quickie: When adding a preservative to a lotion master batch, do I add enough preservative to include the FO/EO?

In this post – Back to basics: Making your first lotion! – Leona asked, When adding preservative to a lotion master batch, do I add enough preservative to include the FO/EO? When figuring out how much preservative to use, we want to take into account all the ingredients in the formula. This means the water, aloe…