I don't think it's really damaging, but within a few hours your axe picks and crampons will have rust all over them. It's easy to get rid of, but yeah within a few hours. It's the same stuff that shows up on axes in general, just a lot more of it. A little wd-40 and scotch pad gets rid of it. I was just surprised by it, but it may have been because I was lying on a fumarole for awhile waiting for my partner to downclimb.