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Contaminated pickle


#1

Over the past few months in a couple of different threads, I’ve
noticed what appears to be contradictory It seems that
one school of thought holds that if iron is introduced into the
pickle, it (the pickle) is permanently contaminated and must be
changed. This has always been my belief as well. I’ve never pushed the
theory because the thought of needlessly going through the exercise of
neutralizing and disposing of the solution irks me more than my
curiosity prods me.

In another thread a couple of weeks back several people advised that
one could introduce iron to the pickle, flash plate a piece, remove
the iron and all would be well again. Could someone among the less
scientifically challenged comment on this seemingly conflicting

Hank Paynter


#2

Just use the pickle. If it doesn’t seem to be working for you as
expected, dispose of it and mix up a new batch. Steve.

Steven Brixner - Jewelry Designer - San Diego CA USA
mailto:@Steven_Brixner4
http://www.brixnerdesign.com


#3
 several people advised that one could introduce iron to the pickle,
flash plate a piece, remove the iron and all would be well again. 

G’day; When sterling is pickled in Sparex or any other acid solution,
it converts the copper oxide on the surface of the sterling to a
soluble copper salt.

When iron is introduced it forms an electrolytic cell with the
silver. If you were to connect a voltmeter to the iron and the silver,
you would see that a current passes. It is this electric current
which carries copper from the pickle over to the silver, thus
electroplating a very thin film of copper over the silver. As soon as
the iron is removed the plating stops. Although the pickle will now
contain a little iron salt, it will not interfere with the pickling,
unless another piece of iron is introduced. Thus it is not necessary
to get rid of the pickle until a pronounced pale blue colour is
visible. The thin plating of copper is easily removed by either
buffing, or heating and re pickling, or adding a little hydrogen
peroxide to the pickle. Cheers,

John Burgess; @John_Burgess2 of Mapua Nelson NZ


#4

Hank, my experience has shown that a quick exposure to iron will not
contaminate pickle. Once the iron or steel is removed, the reaction
(a battery, really) is arrested. A large amount of iron or steel left
in the pickle over time, however will contaminate the solution if
enough is dissolved into the solution. Clean pickle will not copper
plate, since there is no copper dissolve into the solution to be
available for plating out. Flash plating a piece in truly
contaminated pickle will only strip the copper from the solution and
do nothing for the ferric ions dissolved into the pickle.

When I break a drill bit off in a piece and don’t have the patience
to dissolve it away in an alum solution, I throw it in the pickle
(which is rarely blue, since I work mostly in golds and silver and so
is not copper heavy), the hot solution dissolves the steel quickly and
ususaly copper plates only around the drill hole and at worst over the
piece that had the steel in it. Other pieces are left untouched. The
copper plate is easily buffed away or burns off at the next annealing
or soldering.

Good luck, Andy Cooperman


#5
   one school of thought holds that if iron is introduced into the
pickle, it (the pickle) is permanently contaminated and must be
changed. ...  ... several people advised that one could introduce
iron to the pickle, flash plate a piece, remove the iron and all
would be well again. 

It’s a little of both, but mostly the second.

What happens when you introduce iron into pickle is that some iron
dissolves, forming iron sulphate. Now, if the iron is IN CONTACT with
your silver or gold, AND there is already copper oxides dissolved in
the pickle (which when dissolved forms copper sulphate), then the
contact of the iron and the silver or gold forms an electrochemical
cell. A battery. The iron is more chemically reactive than the
dissolved copper. so the reaction that can take place which most
conserves energy is that the dissolving iron displaces copper, which
then literally electroplates back out. But for this to happen, the
reaction needs currently dissolveing iron in contact with the silver
or gold. You can have iron in the pickel and not disturb silver that
is not part of the circuit (electrically connected to the iron),
though if it’s close enough, you can get a partial circuit forming
just through the liquid too, if there’s enough copper in solution.
But mostly, it needs iron, as iron, in contact with the silver. Once
the iron is already dissolved, it’s pretty much out of the picture in
this regard. So if you briefly make a mistake and dip some iron in
the pickle, and copper flash your piece, if you then remove the iron,
most likely the pickle is not ruined.

but the other side of it is that if you get ENOUGH iron, (or several
other chemicals) contaminating the pickle, then it’s possible for
other effects to occur. Usually more subtle, like items starting to
come out of the pickle looking dingier. And if there’s enough iron in
there, that that too can, in some instances, start to plate out,
especially when alloys containing zinc are in the pickle. the result
is usually yellow or rose gold items coming out the pickle looking
somewhat paler and dingier than you’d expect.

Most of this is common sense. If your pickle is badly contaminated
and full of junk, replace it. You’ll know when it’s time because it
won’t be working right any more, or your pieces will be etching or
coming out dingy or discolored in ways you didn’t expect. But you
don’t need to do the Knee-jerk reaction of replacing it the moment
some iron has touched it either.

And on that subject… if your item has come out of the pickle
accidentally plated with copper, and it’s inconvenient to just buff it
off, mix up a small amount of new, cold, sparex type pickle. Add a
little hydrogen peroxide. That will remove the copper. The solution
does not last long, so discard when done.

That dingy whitish look that comes from really trashed pickle will
sometimes clean up with just a bit more time spent in your newly mixed
pickle…

And another useful conclusion to the discussion of copper plating is
this: If/when you break a drill bit or burr, or bit of sawblade, even,
in your work, one of the easiest ways to remove it is just to soak it
in the pickle, which dissolves the broken drill bit. It also causes
some copper plating, often mostly around the drill hole, if the pickle
is older and contains dissolved copper. If it’s new, it won’t plate
out 'cause there’s no copper in the solution to deposit. Either way,
you don’t then have to replace the pickle just 'cause you used it to
etch out a broken drill tip… Nor do you have to absolutely avoid
using your regular pickle to remove that drill bit. Just don’t pickle
it with a bunch of other good items at the same time.

Hope this helps.
Peter Rowe


#6

Over the past few months in a couple of different threads, I’ve
noticed what appears to be contradictory It seems that
one school of thought holds that if iron is introduced into the
pickle, it (the pickle) is permanently contaminated and must be
changed. This has always been my belief as well. … In another thread
a couple of weeks back several people advised that one could introduce
iron to the pickle, flash plate a piece, remove the iron and all would
be well again. Could someone among the less scientifically challenged
comment on this seemingly conflicting

The easy thing about this is you can test it–pour out a little
pickle into a container and stick some steel or iron in it. Test
pieces both while the iron is in the pickle and after you take it out.
You’ll find, as many of us have, that after the iron is removed, the
plating no longer occurs. Of course, if you have old pickle that
rusted the inside of the can, you will permanently have iron in your
mix, which both copper plates the metal, and, on longer exposure,
deposits iron.


#7

Hello This is what I do with contaminated pickle. Just put two piece
of stainless steel in it who are connected to some kind of direct
current power supply. This supply should be at least 4 Volt, more
works only faster ( from a battery loader or something). You will see
that on the - pole the plate will be copper plated or full with some
dirt settlement. This process takes only a 10 minutes. When no setting
occurs your pickle is clean again.

Martin Niemeijer


#8

Our pickle pot had several pieces of jewelry in it when someone
placed a piece of jewelry in the pot that had a small piece of binding
wire attached. It seemed to plate every piece in the pot with a rusty
color. It can be buffed off some pieces but I have a few pieces with
intricate work that the buff can’t reach. Is there another method or
solution I can use to remove this discoloration.

Best Regards,

Randall Brooks
brooks@heirloomsinjewelry.com


#9

I have found that if you reheat and pickle the piece a few times you
might (not a guarantee here–you MIGHT) get rid of it. There are ways
to remove plating (which is effectively what you have done here) but
you would have to look in some manuals on plating for this.

Daniel R. Spirer, GG
Spirer Somes Jewelers
1794 Massachusetts Ave.
Cambridge, MA 02140
@spirersomes
http://www.spirersomes.com


#10

Put some of your pickle in a dish that is just big enough to hold the
discolored pieces. Add peroxide (drugstore variety) to it and add the
item. You should see bubbles appear on the metal. You have made a
stronger pickle that will remove the copper plating but can also etch
solder. Watch carefully and remove your metal as soon as the copper
coating is gone. This pickle will not be effective long so it has to
be mixed each time that you need it. I’m sure the John B. can hop in
here and explain much better than I.

Marilyn Smith


#11

Randall I constantly had that problem when I would do a repair and
that piece would have something with steel ( catch ) or a chain that
had been chrome plated (silver ) ,it would copper coat everything I
put in there because it became contaminated. I finally switched to a
citrus pickle solution and im real happy with it. It takes a little
bit longer to remove the boric acid coating ,but not too long. It sure
beats having get up wash the pickle pot , make a new solution and
polish that copper coated item. Hope this helps :slight_smile:

Cecena’s Jewelry
Antonio Cecena
http://www.CecenasJewelry.com


#12

this discoloration is copper plating that was pulled out of solution
(the copper is in solution in any frequently used pickle) and applied
when the iron was allowed into the pickle. this happens, the only
thing I’ve ever been able to do in this situation is either clean
piece mechanically,very difficult in/on crevices, or plate over top
of contamination. this is unfortunately a major learning experience
to anyone who has the misfortune of having a piece get ruined in this
way. on the bright side you now clearly know why you never let iron
get anywhere near your pickle solution. my
condolences Dave


#13

Hi Randall,

I have had this problem may times & use a weak solution Of Nitric
acid. The red colour is copper being plated onto the peice by
electrolyses. I dip the piece into the weak nitric for a couple of
seconds & it removes the copper plating from the piece. Be sure to
wash the piece to remove the acid & don’t try this on anything that is
hollow. It affects the whole surface of the artical & can dull off
polished areas. I only use this method where polishing is not
practical. Nitric acid can be used to refine gold alloys. It desolves
the alloys & leaves the gold behind.

I once used Nitric acid to remove a broken drill bit from a ring I
was making. I left it in the solution over night. It removed the
drill bit OK but also removed all the alloys from the ring. It left a
24 ct honey comb ring. Quite attractive but not what I was after. ;-(

Good Luck

Dean Watson in + 40 deg C Australia.


#14
Put some of your pickle in a dish that is just big enough to hold the
discolored pieces. Add peroxide (drugstore variety) to it and add the
item. You should see bubbles appear on the metal. You have made a
stronger pickle that will remove the copper plating but can also etch
solder. Watch carefully and remove your metal as soon as the copper
coating is gone. This pickle will not be effective long so it has to
be mixed each time that you need it. I'm sure the John B. can hop in
here and explain much better than I.

G’day Modom; you rang? Well, I reckon that the acidic peroxide
oxidizes the copper on the surface of the job to cupric oxide and
almost instantly the acid converts the cupric oxide to copper
sulphate. Presto!! The reason why it doesn’t last long is because the
peroxide quickly dissociates, and is effectively gone. Just add a
little fresh peroxide to do it again. But sodium bisulphate is so
cheap when bought as pool control chemical, just chuck it away and
make up fresh. Cheers,

John Burgess; @John_Burgess2 of Mapua Nelson NZ


#15

I want to thank everyone for all the help with my contaminated pickle
problem. I tried the nitric acid and the hydrogen peroxide solutions
and both worked well. However, I was a little leery of trying the
cyanide solution.

Dean W & Sue McA, I noticed you mentioned a ring having all the
alloys dissolved from it using nitric acid which left a shell of 24kt.
I wonder how effective it would be to use that solution to dissolve
non-gold metals and contaminates from bench sweeps, buffing lint and
the like.

Does anyone have an opinion on that?