On Fri, 15 Apr 2005 18:33:54 -0400, Alan King <
alan@...> wrote:
>
> Well I was thinking make more bubbles. If you have enough bubbles
> 1/4" or
> 1/2" shouldn't be a problem, more like a circulating foam..
>
Well, too much foam will not be good, if it overflows the container ;-)
So far i have noticed foaming is not a problem, the CuCl readily releases
the air and one can safely assume the increase in volume is only dependent
on air flow. I don't know if other etchants foam more, FeCl is used in
foam etchers but i dunno if there is a foaming agent used.
The whole thing meaning, in CuCl the foam doesn't circulate because the
bubbles only go up, but it isn't a problem as with more air the same
effect can be achieved.
> Yep test plates in a normal tank to figure the angle. May be easier
> to have
> a straight tank and insert type plates anyway..
> If you've got 2 bubble tubes one on each side with enough bubbles, and
> enough
> slope forcing the bubbles in, the board should stay fairly centered as
> long as
> about the same amount of bubbles are on each side I think..
> Hmm two bubble tubes touching and the board sitting in the groove
> between
> them should do it. Bottom 1/4" or 1/2" may over etch but that's a small
> price
> to pay for simplicity.
> Hard to keep the tubes aerating evenly in a fishtank but I think
> nothing will
> grow in etchant. Still may clog over time but I think they're cheap..
> Alan
What i do not know is if bigger or smaller bubbles are better.
think/tinker is sure big bubbles are good, 'cause small bubbles are not
causing enough scrubbing action. OTOH i have tried big bubbles, and it is
hard to get them evenly distributed over the board and they tend to form
vertical streaks on the board that are 2 to 3 times faster etched than
other places. I will rather have smaller bubbles, and slightly longer
etch, if it is even.
ST