Anti-perspirant stains

From the onset of puberty until just recently I was a loyal deoderant user. I shyed away from anti-perspirant because it often irritated my armpits and it always crumbled when I tried to use it. When deoderant stopped cutting it I made the switch. So I've been an anti-perspirant user for just over a year now. That being said, it brings me to my issue of the day: Anti-Perspirant stains. What's up with that? I went out today in a tanktop and much to my chagrin my armpits left big white stains on the straps of my backpack. That's no good. I want the protection without the milky pits. I also realize that they make clear antiperspirant these days and I should've hopped on the bandwagon but that doesn't take away from the faulty design of the white style stuff. I've also noticed that a few of my shirts are getting permanent pit marks. You can't see it from the outside, just on the inside but c'mon. Moral of the story is anti-perspirant works better but has a faulty white goo problem.