Homebrew PCBs

I would like to switch to cucl for a while cause having a solution that 
lasts virtually for ever seems to be very beneficial. Besides, I'm just 
before building a new etching tank and thought that this would be a good 
moment for a switch of the etchant too. Since english is not my native 
language, I always felt a bit unsure if I understood things correctly if 
you guys were talking about cucl in the past, and there were always some 
open ends. In particular the following things are not yet clear to me:

So, one would i.e. need to build 3l HCL/H2O2 and put in half a pound of 
copper into it? Correct?
How many HCL and H2O2 to get to a 3l solution to start with? I mean 
what's the ratio of HCL to H2O2?
Any restrictions regarding the kind of copper? I do have copper left 
over that I use for the anodes in my through plating station. Would that do?

Then, Stefan wrote " If you want to measure this, you can get a 
hydrometer. The ones sold for car battery acid checks will usually do. A 
refractometer should work as well."

A hydrometer - when useing google - seems to be a device to measure 
humidity? Correct? What is a "refractometer", which of the two would be 
easier to get and where, and how would one measure what? Regarding the 
"air stone bubbler", I think I remember that one uses this to regenerate 
the solution. If so, does one have to do this every once in a while, or 
only during etching, or just before?

I'm sorry if these are dumb questions, but since working with chemistry 
might be dangerous I want to be very sure I understand things correcly 
bevore I start to experiment.

TIA

Markus

DJ Delorie schrieb:
>
>
> "Stefan Trethan" <stefan_trethan@... 
> <mailto:stefan_trethan%40gmx.at>> writes:
> > If this feature is very important to you just throw some scrap copper
> > in and etch it away, that'll rapidly increase the density.
>
> This is what I ended up doing - I wasn't using the HCl/H2O2 solution
> often enough and had to keep evaporating off water to fit in more
> H2O2, so one day I just dumped about half a pound of copper into the
> bucket and let it dissolve over a couple of days. *Then* I dumped in
> some H2O2 to "charge" it (it turned from brown to green) and it's been
> stable since then.
>
> At this point, my solution is so dark green that you can't see the pcb
> when you're etching it. Etching takes about 5-6 minutes, plenty fast
> enough for me.
>
> I calculated the ratio at about 1 lb copper to 3 l solution.
>
>