One note here.
While electroetching with Cyanide is effective and produces a
smoother etch than Aqua regia (which doesn’t actually need to be
concentrated, for a slow etch, half and half with water will work,
and fumes less), there is one major problem I’ve found with etching
with cyanides, and that is finding a decent resist. Photoresists
(like Kodak KPR) work, but a number of the commonly used acid
etching resists don’t seem to hold up very well under the very
alkaline conditions of a cyanide, especially if it’s at all
warm… You may need to experiment some, here, to find something
that works well enough. My actual experience in this has not been
with attempting to etch, but simply to selectively stop off areas
while plating. Finding a stop off that will withstand extended
immersion in cyanide, and that would also be a good etching ground,
has been problematic. The stuff I’m using now, a rubberlike
paint, sticks like a sonuvagun, but it sure would be hard to use as
a drawing ground for etching…
Hope this helps.
Peter Rowe