The most commonly validated natural or nature-derived systems include radish root ferment filtrate, leuconostoc ferment filtrate, ethylhexylglycerin paired with pentylene glycol, sodium anisate and sodium levulinate combinations, and low-level phenoxyethanol kept under 0.5% for some clean-beauty standards. Efficacy depends heavily on the formula's water activity and pH, which is why a specialist cosmetic formulator — not a generalist — is essential for getting the combination right.
Read the full guide on cosmetic formulator who specializes in natural preservatives →