Most of us have used copper at one time or another. Probably today
even. It gets used for all sorts of things around the shop.
So, yes, pickle will clean it. Better than anything else, actually,
since it’s mostly the copper in the other alloys that causes
problems, and thus needs to be dissolved.
Don’t be afraid of the pickle. If you have sparex, it’s just sodium
bisulphate. Same stuff used in swimming pools to adjust the PH. Not
fun if you get it in your eye, but it’s not going to dissolve your
fingers. Fear not, and use it with appropriate safety gear (glasses)
and you’ll be fine.
(Don’t know for sure what the ‘citric’ pickle is, but probably just
citric acid.) (All of this goes out the window if you’re really using
sulphuric acid, but almost nobody’s still doing that these days.) (If
you didn’t have to make a point to seek out sulphuric acid to mix
your pickle, you don’t have it, so you can stop worrying.)
As far as disposal goes, you’ll have to contact the local waste
people wherever you are. You can neutralize the pickle itself with
baking soda. (use baking soda, but put it in a little at a time, as
it’ll foam amazingly.) The real issue for most city water treatment
folks isn’t the pickle, it’s the dissolved copper salts. (the stuff
that makes it turn blue.) How you get rid of that is determined by
where you are, and what they want you to do with it. Whatever you do,
don’t ring them up and ask if you can dump “acid” down the drain.
Not only will they say “NO!”, they’ll likely go into orbit, and
nothing you say after that will matter. If on the other hand you say
that you have a bucket of water with sodium bisulphate pool PH
adjuster in it, that dissolved some copper, and now has dissolved
copper salts in it, and want to know the proper way to dispose of
it, they are much more likely to give you a sensible answer.
I’ve never tried Black Max on copper deliberately, but I know it
works on bronze, so I’d figure it’d work on copper too.
If you leave it on too long, it can create a layer that’s too thick
and flakes off. Try putting it on and then immediately rinsing it
off with water.
See how that works. Failing that, fry it with a torch, and it’ll
turn black. Or use liver of sulfur.