Homebrew PCBs

I use an hdpe tube (used for ice-makers or some such) and drilled the
smallest possible holes (.024 - about .6 mm).  by trial and error I
found that if I space the holes closer together towards the sealed end
of the tube, I was able to get fairly uniform bubble distribution.  I
heated up the tube first with a torch and bent it to shape - kind of a
"J" when the bottom is almost as wide as the tank.  This took multiple
trials as overheating hdpe is not a good thing :).  In the end, I got
something that is butt-ugly but works well enough.  The bubbles aren't
small but I get very even etches.

--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
wrote:
> Does anyone know if those flexible air bubble hoses used for fish tanks 
> are any good for ferric or CuCl etch tanks ?
> 
> see,  http://store1.yimg.com/I/animalworldnetwork_1863_24150004
> 
> I know they have a lead metal insert that gives them ability to be 
> shaped, and provides the weight. If this lead is not covered in plastic 
> then it will not stand up to these etchants after a while. I've just 
> ordered some to try, as I'm having bad luck with other "air stones"
sold 
> at aquarium stores.
> 
> I've tried garden "soaker" hose, but the consistency of air release is 
> very poor across its length. Its not designed for fish tanks.
> 
> I've also tried a series of 1mm holes in PVC tube, but the air bubbles 
> are too large causing very low back pressure. Again this gives very 
> non-uniform bubbling across its length. I found the air volume
needed to 
> get good back pressure way too high (tested with water tank and a 
> compressor).
> 
> So I've come to conclusion you need lots of evenly distributed small 
> bubbles to get uniform agitation.