On Sat, 26 Nov 2011 20:07:42 -0800, wrote:

I was testing a new batch of CuSO4 solution for electrolytic etching
on a scrap piece of brass. The result is he

http://www.flickr.com/photos/2768312...in/photostream

I am puzzled at the circular defects which are exclusively associated
with the numbers. The only answer I could think of was more bubbles,
but why? This is a process that does not generate any gas so unless it
is the dissolved air coming out due to heating (about 25W dissipated
in the bath) I just cannot explain it. Also, why are the defects
present only inside or over the numbers? I do not see them anywhere
else.

I have done electrolytic etching with brass before but not a
"positive" etch like this one. Never seen a similar phenomenon before.

On the bright side the steel etching is working like magic:

http://www.flickr.com/photos/2768312...in/photostream

Michael Koblic,
Campbell River, BC


They are obviously plugs put into the base metal.
What was the base..some sort of saw blade? It has the knock out in the
center

Gunner

One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch