The water slows down the evaporation letting it linger long enough to be useful (at least that's what I think I read). Either way, 70% is gentler on skin. 90%

The water slows down the evaporation letting it linger long enough to be useful (at least that's what I think I read). Either way, 70% is gentler on skin. 90%+ is great for cleaning oily stains and whatnot.