Aha, now I understand. Thanks Stefan.
If the board is not perfect verticaly, but a little bit inclined at
30∗ or less, maybe will be same effect.
Adrian
--- In
Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
>
> The discussion back then was the lower edge of the board etches
faster -
> why?
> probably because the bubbles hit the lower edge, but then drift away
from
> the board as they rise.
> If one would put a wedge "guide" there, combined with largish
bubbles,
> that would press them against the pcb all the way.
>
> ST
>