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Home Cosmetic Science Talk Formulating glycerin and preservatives.

  • glycerin and preservatives.

    Posted by lipstickgirl on March 26, 2016 at 9:22 pm

    I have a question regarding a pressing medium for cosmetic glitters.

    I am using 90% isopropyl alcohol at 75% of the formula, glycerin at 25% of the formula then adding cap 5 at 1% of the total weight of the liquid.

    Cap 5:
    Phenoxyethanol, Caprylyl Glycol, Potassium Sorbate, Hexylene Glycol. The Caprylyl and Hexylene

    Is this adequate to preserve the finished product from bacteria & mold once it is mixed with cosmetic glitter and pressed?

    lipstickgirl replied 6 years, 12 months ago 3 Members · 5 Replies
  • 5 Replies
  • lipstickgirl

    March 26, 2016 at 9:44 pm

    Is glycerin a problem in this formula considering that it is a humectant. Will it cause bacteria in the finished product regardless of preservative being added?

  • MarkBroussard

    Professional Chemist / Formulator
    March 26, 2016 at 10:00 pm


    Actually, glycerin is a polyol … it has 3 hydroxyl groups. instead of 2 (glycol).  No, glycerin will not facilitate the growth of bacteria in a finished product.
  • lipstickgirl

    March 26, 2016 at 10:04 pm

    Thank you Mark. So do you think this is a safe pressing medium/binder for pressing cosmetic glitter?

  • Bill_Toge

    Professional Chemist / Formulator
    March 26, 2016 at 10:31 pm

    you’ve got 67.5% w/w isopropyl alcohol in your formula, so there’s no chance of anything even surviving, let alone growing in there; in my view, your existing preservative is unnecessary

  • lipstickgirl

    March 26, 2016 at 10:43 pm

    Thanks Bill! I guess my primary concern was the water from the alcohol and the gylcerin drawing moisture into the finished product casing bacteria and fungus to grow.