I am using CuCL as an etchant and this needs no H2O2 at all. I have
had about 15 litres sitting in a plastic picnic cooler for over 6
months and it is just fine. Whenever I need it, it is there and it has
never failed me, so your warning about etchant deteriorating is not
warranted for CuCL. The solution does need periodic additions of water
and HCl to maintain it, but so far it has not needed any of these.
Onygenating is important, but vigrous passage of air through the CuCL
during etching has been enough, so far, to regenerate the solution.
For those who are interested, some CuCL details are here:
http://users.rcn.com/rexa/Projects/CuCl_ech.htmland the Links here have more info about CUCl.
Grant
--- In
Homebrew_PCBs@yahoogroups.com, "cybermace5" <cybermace5@y...>
wrote:
> --- In Homebrew_PCBs@yahoogroups.com, "grantfair2001"
> <grant.fair@s...> wrote:
> > Twenty-five litres? I thought 5 litres would be a life-time
supply! I
> > haven't adjusted the cupric choride I have in the big picnic
cooler
> > since I made the solution, and I have made lots of boards in it
since,
> > but it seems to be slowing, so it's time to check the density and
> > titrate to determine acidity level.
> >
> > How the heck am I going to use 25 litres, do you imagine?
> >
> > Grant
>
> The stuff you get from a hardware store is muriatic acid, about 31%
> HCl concentration. It's not the nastiest chemical ever, but it's
about
> the nastiest you can easily find for sale. Should be treated with
> respect. Use it outside or with lots of ventilation, away from any
> metals you don't want rusted or dulled by the vapors. You don't
really
> dilute it that much to etch PCBs, but it is pretty cheap. When you
add
> the H2O2, it'll start outgassing. Don't breathe that stuff, it'll
chew
> up your lungs and throat. Always add the acid to water, not the
other
> way around. Keep a bucket of water and an open box of baking soda
> nearby to dilute and neutralize any accidents. Don't ever put
aluminum
> into the etchant mixture, it violently outgasses hydrogen and
produces
> a lot of heat: bad combination for something happening in a tank of
> corrosive acid. You also don't want to leave mixed etchant sitting
> around, it'll degrade pretty quickly.
>
> So...HCl works and is cheap, but can be a bit of a pain to use. Of
> course there are other neat things you can do with your HCl,
including
> some interesting metal etching/rusting and wood finishing effects.