[Sun Care] Does white cast serve a function?

Beauty Tips For Body Care
I think I've found my HG sunscreen (the Bioderma Photoderm Max 50+ that other others have reviewed on here), but it does leave a slight white cast. What I can't figure out is what that means. Does more of a white cast mean it's getting better coverage? Is it only getting enough coverage where there is a white cast? In my mind, I can see it going either way - either a white cast means there's too much product globbed up, or a lack of white cast means there's not enough product. The white cast seems to be there whether I use less or more than 1/4 tsp, so there doesn't seem to be a linear correlation amount of product and amount of cast. And finally, if I wait for it to "set" and then blend it with my fingers, how do I know I'm not just rubbing it off?TL;DR: is white cast a sign that sunscreen is working, or a sign that I haven't blended enough?
Girls Blog 2015
Submitted by killajoule_jewelkill