I would like to amend this post a bit. Coral no longer carries ImagOn and I no longer know of a source to buy small amounts to try out. Unfortunate because it is such a great product for those who are fed up with PnP and/or who want to get fine detail. I now buy from takachpress.com in a 12 inch by 15 foot roll. I also have not gotten around to writing up a tutorial on how I do the exposure and developing, but I do have a link to a fairly similar technique by Nancy L. T. Hamilton. Nancy uses Puretch which is essentially the same as ImagOn.
PurEtch is available from capefearpress.com. Jennifer is a pioneer among printmakers. She developed an excellent system for high definition imaging on metal, and very generous with her support. If you have a question you can't find the answer to on her web page, just call her. She may not speak "enameling," but she knows etching.