I've used the sponge method on boards up to 2 ounce copper. It just
takes longer. Definitely get the green film if using the sponge
method. It is very effective in protecting the toner from the rubbing
action.
A 75mm by 100mm board with 1 ounce copper takes about 5 minutes to
etch. I also cover all unused areas with toner to reduce the rate of
etchant exhaustion. This size board takes about 1 ounce of etchant.
--- In Homebrew_PCBs@yahoogroups.com, "schabtach" <adam@...> wrote:
>
>
> Alternatively, has anyone tried the sponge-etch method with 1 oz.
> copper stock? 1 oz. / 0.032" stock seems to be readily available.
>
> Thanks in advance for any replies.
>
> --Adam
>