Oh cool. From what I've found, it looks like the optimum temperature
for Cu++Cl2 etchant is 130 degrees F. Were you using a heater? (Could
an ice chest withstand a heater?)
H2O2 would be an ideal rejuvinator. That extra oxygen atom would
really do the trick. It seems like nearly all reactions involving CuCl
produce H20 - with the addition of H2O2 doesn't the solution end up
being "watered down?"
I took a fish tank heater -- adjusted to some hottish temp (I can't
remember the details) and replanted it in a large test tube with
chemistry rubber stopper and tight sealing enforced for wires and all
junctions with some kind of "glue" - might have been silicone. I think I
sealed it hot to minimize expansion pressure.
With the tight sealing, I got the whole heater horizontal at the bottom
of the tank. The cooler container has survived so far - only a few
attempts really, but I don't see problems from the heat.
On the rejuvenating -- the original article (none of it my work-I just
provided what I found interesting) has the details. It is not simple.
You need to monitor both specific gravity and the acid level, by
titration.
I accumulated enough chemical supplies and kludgy apparatus to get it
done. It is not simple. I doubt if a dash of this or that each time
would suffice very long.
On the FeCl side, the original author of my method offered one of the
best sounding suggestions I ever heard for disposing of spent FeCl
solution -- Use it to mix with cement (concrete). Send the resulting
brick to the dump. Any bad stuff should be tied pretty tightly inside
this brick. Way better than pouring down the drain or somewhere else.
All these methods have potential negatives. It was mentioned earlier
that either solution in a bubbler creates corrosive or staining spray if
not carefully contained or cleaned. The HCl in in the CuCl will creap
out and attack nearby metals if not tightly sealed, even just sitting
there.
I'm no real expert on any of this, but I have tried it.
