Refillable formats are exposed to air and potential contamination across multiple openings, so preservative robustness is critical. Cosmetic chemists commonly use broad-spectrum systems such as ethylhexylglycerin plus phenoxyethanol, or EU Annex V–compliant alternatives like sodium benzoate blends for natural positioning. Preservative efficacy must be confirmed by ISO 11930 challenge testing.
Read the full guide on how to find a cosmetic chemist for refillable packaging formulas →