On Wed, 02 Nov 2011 20:46:05 -0700, wrote:

On Tue, 01 Nov 2011 20:43:38 -0700, Larry Jaques
wrote:

On Tue, 01 Nov 2011 17:41:46 -0700, wrote:

But back to the original problem - I think I found the solution. The
bubbles *are* a problem and if one keeps the electrodes 1" apart and
vertical the etch is pit-free.

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

Cool! Now to figure out why 1 inch is the key to pitless etching of
that material with that solution and power supply. Maybe a perfect
multiple of the bubble width?

Nah, the bubbles just don't go near the anode. I suspect the poor

I think I was referring to any electrical characteristics of the
electrolyte may have, wondering if it equated to bubble (or potential
bubble) size. I know that there are shadings in solution, so parts not
directly in line will have different etch characteristics. Jeeeze, I
haven't done any etching in a couple dozen years, and even then, it
was plating. g


result on Plate 5 was because the precipitate was holding the bubbles
in the electrolyte and they got closer to the anode. Although plate 4
was closer to the cathode the electrolyte was clear and the bubbles
were free to escape.

What precipitate? The etched material?


Tomorrow I am going to look at a container big enough and narrow
enough to do some of the bigger pieces side-by-side so there is enough
space between the electrodes yet I do not have to use a gallon of
electrolyte every time.

Is this entirely sacrificial, or can you reuse electrolyte?


Anyway, I moved onto brass today which I thought I had pretty much
worked out. I did two small plates and observed some really weird
behavior. OTOH I do not care as long as the result is OK.

Got eight-by-ten colour glossy photographs with circles and arrows and
a paragraph on the back of each one explaining what each one was to be
used as evidence against us?

--
Knowledge speaks, but wisdom listens.
-- Jimi Hendrix