I want to formulate a sunscreen with only zinc oxide and I will be using pre dispersed zinc oxide
I have these problems
1. How much zinc oxide to use for SPF 30 ?
2. How much zinc oxide to use for SPF 50?
3. Also how do I add a mattifying effect in sunscreen don’t want a hydrating sunscreen.
I’ll be using 20% zinc oxide dispersed in iso-octyl palmitate
I cannot afford to make SPF and then run on testing again and again for different SPF I can only take once and run on a professional SPF testing in my country