Optiphen Natural Preservative Optiphen is a unique paraben-free and formaldehyde-free liquid preservative system which consists of Phenoxyethanol in an emollient base of Caprylyl Glycol. Optiphen is a clear liquid preservative that can be easily added directly to the formulation during pre- or post-emulsification at or below 80 degrees C(176 degrees F). Optiphen works best with a pH between 4 and 8. Optiphen is compatible with most ingredients used in the personal care industry. Usage: Optiphen is a broad spectrum preservative. This clear to semi clear liquid can be easily added directly to the formulation during pre- or post-emulsification at or below 80 degrees C. Recommended use levels: 0.5 - 1.5%. The rate of application varies by product but in general 100 mg of product will only require about 1 mg of Optiphen.