Refresher.
Small amount of Hydrogen peroxide.(optional)
Drop in a small piece pf copper and bubble away.
your looking for a dark green color.
This is an excellent write up... the best imho.
http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/ --- In Homebrew_PCBs@yahoogroups.com, "Terry" <twgray2007@...> wrote:
>
> I have a question about CuCl etchant. I mixed up a galon of the stuff using the standard off the pharmacy shelf H2O2 and HCl I normally use in my swimming pool. It worked great in my etchant tank the first time, but I have been unable to get it working again. I've added more H2O2 and HCl but to no avail. The liquid is a nice transparent lime green. Any suggestions on how to recharge the stuff?
>
>
> --- In Homebrew_PCBs@yahoogroups.com, Philip Pemberton <ygroups@> wrote:
> >
> > Right then, time for a quick update...
> >
> > My CuCl etching bath seems to be well on its way. As of last night, it
> > was dark green in colour with white foam and looked like it had oxidised
> > as much as it was going to. I added the last few bits of copper wire
> > (which were left over from the startup attempt) and turned the air
> > bubbler back on.
> >
> > This evening I found the liquid in the tank was completely opaque -
> > white with a hint of green. Almost like someone had dumped a bag of
> > plaster mix in there... Oh dear. This one isn't in the manual...
> >
> > I don't have a hydrometer, so I can't check the specific gravity of the
> > solution. For bonus points, I'm still trying to track down some suitable
> > containers to do the titration test Adam Seychell describes on his webpage.
> >
> > ... However the photos of the "you've added far too much NaOH" titration
> > looked oddly like the contents of my HCl+CuCl tank... which got me
> > wondering -- was the tank low on acid?
> >
> > Turns out it was. I added a bit of acid (by the highly unscientific
> > "just add some with the bubbler on until it's not cloudy any more"
> > method) and the cloudiness vanished, leaving the green-black liquid I
> > had before.
> >
> > It's now back on the air bubbler (and foaming like crazy), though given
> > the colour of the solution I think it may have already oxidised as it's
> > going to (although it went a heck of a lot brighter when I last threw in
> > some peroxide, though I'm all out of that at the moment).
> >
> > --
> > Phil.
> > ygroups@
> > http://www.philpem.me.uk/
> >
>