Being that I used to work in a semiconductor plant (where they use a LOT of Hydroflouric Acid (HF)... HF has a tendancy to react with the calcium in your bones and basically eat them... can do really nasty stuff. Especially since it doesn't react with your skin all that much, you don't feel it. But the damage is done. We had many, many safety classes on dealing with HF. There is some cream you can put on your skin that will help stop it if you get it on there quick enough, but off the top of my head, I can't remember what it is. This was several years ago.

Hope that helps