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Home Cosmetic Science Talk General Off Topic Actives, Percentages & Layers

  • Actives, Percentages & Layers

    Posted by halrac on June 22, 2021 at 7:15 pm


    I have been wondering for a while if applying a cosmetic product on the skin can change the final concentration of the actives depending on how many times you “layer” it.

    i.e. A cream has a 5% urea but I apply it twice. Does it mean that the concentration of urea on the skin is closer to 10% than to 5%? 

    halrac replied 1 year, 11 months ago 3 Members · 3 Replies
  • 3 Replies
  • David

    Professional Chemist / Formulator
    June 22, 2021 at 8:07 pm


  • OldPerry

    Professional Chemist / Formulator
    June 22, 2021 at 8:11 pm

    No because when you apply it a second time you are still only applying 5%. You are also applying the 95% of the formula that isn’t your active ingredient. So, the total on your skin remains 5%

  • halrac

    June 22, 2021 at 8:16 pm

    Thank you both very much!