Etching Holes ...

[R.G. Keen]

>I question whether the acid would eat straight down and not sideways.
>Acids like edges. (You can even sharpen files with Nitric acid.)
I have the same question. I believe that the edges would certainly be
undercut, so to get some control, you'd have to do a deep etch in
stages, maybe. I didn't think it would be perfect, just that the
initial etch would leave the topmost surface in the desired pattern.

Shoot, it might not be workable at all. Quoting Sigmund Freud on an old
Northern Exposure " Vell, it vas choost a theory..."
>
>When glass etchers use Hydroflouric acid to etch glass, they say there is a
>limit to the depth of the
>cut, since the acid wants to eat sideways too.
>
>Maybe this is why we don't see too many acid based metal shops. :)
Yep, you'd have to worry about that.
>
>I also question what substance the resist mask would be made of to resist a
>strong acid.
FeCl2 is not a strong acid, although it is acidic. I know well from
etching copper that doggone near anything will resist it. Fingerprints
can come out clearly if you're not careful with cleaning the copper.
Any oil works. Sharpie permanent markers work. Lacquer works great, and
for long periods.

I don't know how well any of these work with actual strong acids, and I
don't personally recommend the experimentation.

I DO know that the faster the etch through, the less undercutting.

R.G.