what is the chemistry involved with fingerprint dusting?

Answer 1

I think it is a mechanical technique. The powder simply sticks in the oils from the skin left behind on the surface. I am not up on modern techniques, but perhaps some chemical reaction between the powder and some treated paper allows investigators to make copies of the prints.

Electrophoresis is a technique where an applied electric field causes charged molecules to move through a medium; usually a gel these days but paper used to be used. Larger molecules tend to move more slowly, and more highly charged molecules will move more quickly, so you can separate compounds. I don't see how this might be used in fingerprinting.

Answer 2

A way to develop fingerprints is to spray them with cyannoacrylate (crazy glue), a chemical that in the presence of air polymerises. On a surface with an oily fingerprint versus, say glass, cyanoacrylate will 'dissolve' or adsorb more readily with the oil. Self reaction of cyanoacrylate (polymerisation) occurs more readily on the oily portions of the fingerprint and this reaction occurs here, to eventually build up solid material that is visible to the eye. The polymerisation process is the same as if you opened a crazy glue container to the air...within days it becomes hard as a rock.