| This stuff is great. It is used extensively in IC fabrication, especially for photolithography steps as well as in RCA clean procedures.
Being a weak acid, and having no smell, this stuff is really dangerous in the lab. If it comes in contact with you, there is no burning or discoloration of the skin. But the HF continues to diffuse through your skin until it hits something that it can react with. Unfortunately for you (if you spilled this on yourself) that something happens to be the calcium in your bones. This is supposed to be an extremely painful experience, as the hydrofluoric acid literally dissolves your bone. The more concentrated the acid, the more severe the effect. Also, these symptoms can take up to 8 hours after you've spilled this stuff on you. That means you could be in the middle of having sex with some hottie when the HF decides to take its' revenge.
I had a lab instructor once that told us a story about a bad HF experience. She was working in a lab for a small company prototyping ICs, and one of the company execs actually took a tour group of investors through the lab. They had many unmarked beakers underneath a fume hood (since there were only a few technicians working in there), one of which got knocked over by a Japanese gentleman. Well, he picked it up and set it back down, never mentioning it to anyone in the lab. Unfortunately for him, the beaker had contained dilute HF.
This poor guy left and called the next day admitting that he had knocked over a beaker, and the hospital was wondering what the hell it was. The HF destroyed the nail beds of his right hand, and the fingernails never grew back.
Effective treatments for topical HF exposure include a calcium cream, which can be used as a primary treatment, usually followed by injections of a liquid calcium solution all throughout the affected area.
If you ingest this stuff, you're pretty much done for. | 
