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Home Cosmetic Science Talk Formulating SPF Measurement

  • SPF Measurement

    Posted by Rimbaud16 on July 7, 2021 at 3:08 pm

    Hello people, 
    I am young cosmetic formulator and I have difficulties determining the SPF factor ot my formulas (mainly Emulsions). I use Spectrophotometer and relevant software (OptLab5). The problem is there, that even with small amount of UV Filters (for example 5% Ethylhexyl Salicylate, 5% BMDM and 5% Tinosorb S) the software gives me result like 99.0/99.0 for SPF/UVAPF (Colipa 2009). When I use the BASF Sunscreen Simulator and run simulation with the exact same amount of filters, it shows me SPF 20. I want to know how to reliably determine the SPF of my products, is it SPF 20 or SPF 50+ for example? Can someone with experience using similar methods help me, please? 

    Rimbaud16 replied 1 year, 11 months ago 3 Members · 3 Replies
  • 3 Replies
  • seaberry

    Member
    July 7, 2021 at 4:55 pm

    I don’t know nearly enough to help—but don’t you need in vivo testing to establish SPF numbers?

  • Bill_Toge

    Professional Chemist / Formulator
    July 7, 2021 at 5:03 pm
    how much product are you putting on the plate?
    the standard amount required by COLIPA is 2 mg / cm²
  • Rimbaud16

    Member
    July 9, 2021 at 8:01 am

    I use standard plates and I think the amount is 2 mg/cm2. I use the same amount of product when I test for example cream with SPF30 and cream with SPF50. I reach the software provider, but he was so incapable of helping me, talking only about general things, without saying nothing about my questions. I think the software only gives me information about the distribution of filters in the emulsion and these values 99.0/99.0 for (SPF and UVAPF) show me that all of the filters are very well distributed throughout the emulsion and they gave me nothing about the real SPF. Maybe I should rewrite my questions and ask for someone, who has experience with the software, I am using.