Andrew,
If you read the following link, especially the comments at the bottom by other readers, it might help. The one thing I don't like about the way the "sponge etching" process is illustrated, is that it does not take into account the environmental impact. The author talks about rinsing the PCB down the DRAIN. He has no regard for the environment.
http://www.instructables.com/id/Sponge-Ferric-Chloride-Method-Etch-Circuit-Bo/...but it looks like the effectiveness of the etching process depends on your copper thickness.
Frank P.
--- In Homebrew_PCBs@yahoogroups.com, Andrew Villeneuve <andrewmv@...> wrote:
>
> Though I confess to only trying the sponge-etching process once, it was very
> labor intensive and I had miserable results with it.
>
> It took about 15-20 minutes of manually scrubbing the board, and still made
> a considerable mess.
>
> Also, though it worked well with my toner transfer pattern, it scrubbed all
> my resist-ink corrections off the board, even the really dark traces.
>
> I expect my method can be improved upon, but I found that using even a
> simple etching tank was much quicker, even including all of the setup and
> putting away.
>
> -Andrew
>
> On Wed, Jun 2, 2010 at 2:33 AM, Richard <richard.liberatoscioli@...>wrote:
>
> >
> > See if this is a better solution for you:
> >
> > http://www.pulsarprofx.com/pcbfx/main_site/pages/tech_support/no_etching_tank/no_etching_tank.html
> >
> >
> >
>
>
> [Non-text portions of this message have been removed]
>