So we’ve spent some time getting to know our preservatives, so let’s take a look at what preservatives we might want to use and those we should avoid when creating our products. Let’s say you’re making a scented body spray and you want to use polysorbate 20 to emulsify your fragrance into the water based...

There’s one more thing to consider when using our preservatives – inactivation by cellulose derivatives! In this study, various cellulose derivatives were tested with various preservatives to see which ones retained their efficacy. Here’s the list… Methylcellulose reduced paraben efficacy. Methylcellulose, sodium carboxymethylcellulose, and hydroxypropylmethylcellulose all reduced phenoxyethanol efficacy. Gelatin reduced paraben efficacy. Polyvinylpyrrolidone (PVP)...

I bet you never though your pigments could have such an effect on your preservative system – but they do! As with the inactivation of preservatives by non-ionic ingredients, this problem is one for the parabens. If you make mineral make-up, this really relates to you! (Click here to read the entire study.) Inorganic pigments...

I mentioned in the parabens post that some preservatives – mostly the parabens – can be inactivated by non-ionic ingredients, including some of the fatty alcohols (like cetearyl alcohol), fatty acids, esters, and polysorbates, when they’re used as emulsifiers (using the HLB system). The paraben based preservatives include Phenonip, Liquipar, and Germaben II, and the...