I have used both ImageOn and Puretch for etching silver with nitric
acid. I learned how to etch with ImageOn and liked it but the
formula kept changing. I don’t think ImageOn is available any more.
The newest version is ImageOn Rapid. Both ImageOn and ImageOn Rapid
have to be thinned before they are exposed to light. No big deal but
it is one extra step. I tried Puretch when I could no longer get
ImageOn but it did not hold up in nitric acid. Now I use Zacryl…it
does not have to be thinned…they don’t keep messing with the
formula…and it holds up as a resist in nitric acid. Good luck.