Learn about the problem of sunscreen formula. In the formula there is
Zinc Oxide EasyDisperse (5%),
Titanium Dioxide EasyDisperse (5%) and
PMMA Booster (5%) but only got SPF 4.5, so I would like to ask you why you get low spf. Expected to get 25*2 = 50 and ask for advice on how to solve the problem to increase the SPF value to 30-50, thank you.