If the etching is one of a kind, I recomend looking for the name of the artist on the etching. If there is a name, you can look up the artist and get a general idea of what a piece of his/her art is worth. If there are more than one sculpture/etching of this same theme. Try to find the price or value of the other.
Hydrofluoric Acid. It actually depends on if the HF has a aqeous or (aq) symbol behind it it it does than it is Hydrofluoric acid but if it doesn't then it is Hydrogen Fluoride The chemical name for HF is hydrofluoric acid. Hydrofluoric acid is simply just a solution of hydrogen fluoride that is in water.