I haven't been able to find a straight answer for this in the book. I have seen the rules for if your armor breaks, but that implies it takes damage, but that will just mean my players leaving after every fight as they mostly have leather now and it will for sure be destroyed?
Special attacks that explicitly say they dent (or worse) armor, like found on the ankheg (whatever it's new name is, I can't remember) are what damage armor.