Stephenson Shampoo Bar Preservative?

[KudzuGoddess]

All, please help me with the Stephenson Shampoo bar. What preservative do they use and do I need to add more if I add stuff? I get that their product is trademarked so they don't want to disclose everything but there has to be a preservative, right? Water is one of the few ingredients that they do list. Water=Life. What am I missing here? I am very new at this so please excuse my ignorance if this is a dumb question. Thank you all, you're the best!

 

[FFLinOhio]

here is one of the ingredients, and the description provided by google
Propylene glycol is used as a softening agent, preservative, humectants, and solvent in cosmetics, fragrances, topical medications, soaps and cleansers, hair care products, and deodorants

 

[artemis]

do I need to add more if I add stuff?

If you follow their guidelines for how much stuff you can add, you shouldn't need to add any kind of preservative.