Homebrew PCBs

I cannot pinpoint why its slow. As I posted ealier I got a piece 
of clean copper in fresh 20% HCl and completely dissolved it in 
little over 3 hours to end up with deep green colored solution. 
You can see from the picture that air supply was extremely 
vigorous so the test dosn't represent a practical situation. It 
became warm (20\ufffdC above ambient) during its peak because of the 
heat generated by the reaction. Unfortunately its been a slow 
week with your setup, and I can understand your frustration.

I haven't yet done a direct comparison between the use of large 
bubbles and fine bubbles and how it effects the reaction rate. 
Maybe there is a 100:1 difference ???. On a more theoretical 
thought, the surface area/volume ratio of a bubble (assuming 
perfect sphere) is proportional to 1/r. For equal volume of air 1 
mm bubbles would give 10 times surface area than 10 mm bubbles.
Any foaming on the surface would also dramatically increase air 
contact area. Small bubbles are much more effective at creating 
foam than large bubbles.

Its expected for splashes to jump out of the tank, you should 
have a lid on. Virtually all the oxygen source is from the air 
bubbles, not the surrounding air.

Adam

grantfair2001 wrote:
> To put the HCl fume problem in perspective - I had been bubbling the
> etchamt solution with an open tank for over a week without any HCL
> damage, even on steel a few feet away.
> 
> It was only when I started aerating with a much higher volume pump
> that the problem appeared. The etchant surface was so agitated that it
> was spitting some etchant out of the tank - and into the air. And the
> bigger compressor got warm enough that the air was being warmed, and
> increasing the temperature of the etchant. I understand a higher
> temperature alone may cause fuming.
> 
> I believe the CuCl approach can be used without any fume damage, even
> without a fume exhaust.
> 
> As to the slow process, this is in part due to my air sparger making
> largish bubbles. If I got an aquarium air stone the process would
> probably be much faster.
> 
> Grant
> 
> --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> <stefan_trethan@g...> wrote:
> 
> 
>>i really believe with this cost / etch i won't start the bubbling
> 
> campaign.
> 
>>this seems much to high effort (concerning the corrosive fuem
> 
> discussion also).
> 
>>regards
>>st
> 
> 
> 
> 
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