Poulette ponders…Can someone help me understand the logic behind how SPF numbers are allocated to sunscreens? I’m thinking primarily of SS using physical barriers like zinc oxide & TO. For example, Josie Maran claims SPF 40 with Titanium Dioxide 9.5%, Zinc Oxide 6.0%, while Snowberry Everyday SPF has 16% ZO and claims SPF 15. There [...]
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