[fridizzle]

Which of these two chemicals poses the most danger? (ABF= ammonium bifluoride)

Are there any alternative chemicals that you could use instead of HF that are safer and less harmful?

[gluedudeguru]

HF is by far one of the worst (common) chemicals you will come across.  If you get any on you it will seep through the skin (with no indication so) and eat the inside.  The agrresive available fluoride ion replaces the calcium in your bones (similar to lead).  It is very dangerous and deadly.  As for replacement, what are you needing these for? Glass disolving/etching (eats the silicone).

FYI ABF is not necesarily as dangerous but can be converted into HF under conditions i cant recall.  Be careful with any chemicals and especially be weary of fluoride containing products

[fridizzle]

Well HF is used for cleaning fossils, so i was wondering if there was another chemical that i could use to clean fossils that is a greener (safer) one?

[csrscience.com]

Hydrochloric acid will get rid of calcium carbonate deposits around fossils. I've done this with horned corral and I've obtained some very nice specimens.

HF and ABF will react with SiO2 and other silicates - and is one of the very few that can - this is probably why it is used and I don't see a way out of using it.