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Silver turning gold in tumbler


#1

It’s my first posting to the site. Thanks in advance for your help.
I’m using almost only silver which I solder, pickle, dip in water,
then put into the tumbler with burnishing solution. Then the magic
happens in the tumbler that half of my pieces are coming out gold!
Looks real nice…but isn’t helping me get orders out. The gold
polishes off with some effort though the chains are too much work to
get off. I’ve changed the pickle, the water, the burnishing solution
and can’t figure out what could be happening. A while back I got
some hydrogen peroxide in the tumbler and maybe it has seeped into
the walls, but that wouldn’t explain why only 1/2 the pieces are
affected. I do use some small pieces of copper and brass, which are
in the same pickle and then I put them in the same tumbler with the
silver. Is this a no-no and could it be a reaction to the mixed
metals?

Many thanks for your feedback.
Emelie


#2

Hi Emelie,

I recently had a similar problem. I was using a new tumbler barrel
(which, incidentally, came with my Chicago brand tumbler, and smelled
strongly chemical.) My silver pieces were coming out yellowish,
almost like they’d been dipped briefly in liver of sulfur. After
trying to clean the shot and the tumbler to no avail, I resolved the
problem by going back to an old tumbler barrel. Eventually I replaced
my tumbler and barrels with Lortone brand equipment, which have been
working perfectly so far.

I did find that a quick dip in Tarnex (the liquid tarnish remover)
cleaned off the yellow tinge. You may want to give that a try, rather
than polishing the yellow off of your silver pieces…that is, if
your issue persists.

Good luck!
Lauren


#3

Yes it is a no no silver should be in its own pickle the brass is
contaminating the pickle.


#4

Emelie

To better answer your question, it would help to know what kind of
tumbler - rotary? Barrel type - rubber or plastic, burnishing
solution - concentration and amount, media - stainless, ceramic,
plain steel, run time, cleaning process prior to tumbling.

Try these things in sequence

Use an ultra-sonic cleaner to make sure that you don’t have pickle
or contaminants in or on your work. Dipping work in water isn’t the
same as cleaning it.

Check your chains to see if there is steel in the clasp.

Make a run with only sterling - use just a couple. That should
separate out whether the tumbler is the problem or what you are
putting in it.

Have you used liver of sulfur on some pieces? Could you have some
iron contaminants - maybe rouge - that would start a plating process.
Do you have sufficient liquid in the tumbler? Are you using a fresh
solution of burnishing compound with each run? Do you clean the media
between runs?

How much stuff do you put in the tumbler? Does the “gold” appear
evenly on the pieces or is it spotty?

To remove the “gold” make a peroxide pickle rather than try to
polish it off.

For what it’s worth - I regularly run mixed metals in my tumblers
with no problem. But - I am rigorous about cleaning the work before
processing. I clean/rinse media after each run. I use fresh solution
in closed batch processing. In flow-thru processing, I finish each
run with a full tumbler rinse of the media. Tumbling works very well
if you are meticulous about cleaning everything.

And if you really want to know how the tumbling stuff works - get
the book - “Tumble Finishing for Handmade Jewelry”. Rio Grande, Otto
Frei and Gesswein have it. Amazon does not.

Judy Hoch


#5

Emelie,

I have heard that sometimes the inside of a new tumbler container
will react with metals. This apparently happens fairly often with a
number of different brands of tumblers.

The solution I have read from many sources is to tumble your steel
shot with flat coca cola in the tumbler for an hour or two. Then take
out the shot and rinse both the shot and the inside of the tumbler
thoroughly.

I just googled this idea. here are the first two links -
http://www.ganoksin.com/gnkurl/ep7z7y
from chainweavers dot com.

http://www.ganoksin.com/gnkurl/ep7z7z [PDF file]

This link downloads a pdf with some good technical info. This pdf
specifically mentions the Chicago brand tumbler.

hope this helps.
Mary A


#6
Yes it is a no no silver should be in its own pickle the brass is
contaminating the pickle. 

There is no reason for this, silver copper and brass can all share
the same pickle with no issues.

James Binnion
James Binnion Metal Arts


#7

Yes it is a no no silver should be in its own pickle the brass is
contaminating the pickle.

There is no reason for this, silver copper and brass can all share
the same pickle with no issues. 

I have to disagree with you, Jim. I never had any trouble with my
silver turning pink until some of my classmates started pickling
brass and copper in it.

Margaret Malm


#8

Hello Margaret,

there must be a unknown factor in your story with your classmates.

Brass is an alloy of copper and zinc. Zinc will not turn red as far
as I know, the copperoxide do. However, in order to do so, there
must be a buffer in order to start that “plating process”. Binding
wire or iron tools will act as a buffer and that will contaminate
your pickle. The pickle wil be contaminated from the moment you
insert iron into it leaving a plated red color on your silver.

Give it a second thought Margaret. IF zinc whould be the
troublemaker, why don’t you get in trouble when you solder silver?
Silver solder is made with silver, copper and zinc. In matter of
fact, it’s made of silver and brass.

I can’t explain the chemical process well but I’m sure others will
do that in detail. So, Jim’s statement is correct in this matter.

Have fun and enjoy
Pedro


#9

I use many many different metals in my shop and I keep it clean by
using separate tool sets for silver and my non-precious metals. I
have had some interesting color washes on silver after I had used
the pickle for brass and bronze. Little crock pots are cheap and so
is pickle so separate files and pickle isn’t a big deal. Never in my
work has reason ever applied to the chemical reactions and results
of metalwork there is always a scientific explanation for each
result. :smiley:

Teri


#10

I agree with Jim.

I use the same pickle for brass, copper and silver. Never any pink on
the silver. Perhaps “classmates”… along with mistakes they may be
making with ferrous metal fragments… are the issue.

Carol


#11
Yes it is a no no silver should be in its own pickle the brass is
contaminating the pickle. 

I come across this conviction every so often, but I have never seen
any indication that it is true. Brass contains copper and zinc.
Silver, copper and zinc make silver solder. And this would surely
not explain only some of the pieces turning yellow!

I would try running the shot with flat coke for a few hours. If that
doesn’t do it, maybe add a baking soda dip before rinsing and
pickling.

Noel


#12

Margaret,

Students are always a wild card, you have no idea what is going into
the pickle pot. I make sterling, copper brass mokume, along with my
gold and platinum work it all been going into the same pickle pot
for about 35 years now and have never had any problems with
discoloration that was not related to iron. So I will stand by my
assertion.

James Binnion
James Binnion Metal Arts


#13

Hey Pedro… Is this the Pedro who spent some time in Lake Country
(Winfield BC) a couple of summers ago making Jewelry with David? If
that’s you please reply to sender for info.

Linda M from Winfield with the studio the size of an elevator shaft! :slight_smile:


#14

I’ve been in metals programs at two different universities now &
every time the pickle starts copper-plating things, it’s turned out
that someone was putting iron or steel in the pickle. In one case, a
student had soldered steel nuts & bolts to a piece. (One thing that
still amazes me is how many times I can repeat something & the
students still do it.).

I’ve found that a good solution for removing the plating is a 50/50
mix of white vinegar & the 3% hydrogen perioxide that you find at
the grocery store. Use it at room temperature & just let the piece
soak for a while. The vinegar mix is less aggressive than the pickle
mix, which can sometimes start to etch into the piece.

Sharon,
Artist, metalsmith, chaos magnet


#15

Hey Orchidians,

I use citric acid instead of the sodium bisulfate. No problems with
iron contamination. Citric acid pickle may take a little longer to
clean things up, but If the solution is hot, there really is not
much difference. Besides, I always have several things going at once,
so the time in pickle is not of concern.

If you are interested in trying citric acid pickle, it is used in
food preservation and in making “bath bombs”. Try your local grocery
store’s canning supplies or go online. Half a cup will make lots of
pickle!


#16

Judy,

thanks so much for the about using citric acid as pickle.
I’ve read this tip before but have never seen a “recipe.” how much
citric acid to how much water? and, do you use distilled water?

Thanks,
Mary Alexander


#17

Hello Mary,

I use a couple tablespoons of dry citric acid in a cup of tap water.
That’s a fairly strong solution, so you can use less of the citric
acid if you want… or more. There is no specific “recipe” for the
mixture.

My pickle pot is a ceramic mug on a warmer - read coffee cup warmer

  • with a chemist’s watch glass on the top for a cover. As the liquid
    evaporates, I add more water to fill the mug. Even when the solution
    is blue-green, it still does the job!

Yup, I like Citric Acid pickle. Gonna’ give my pH Down to my kid
with the hot tub.

Judy in Kansas, who will be taking the grandkid to the swimming pool
this afternoon and will enjoy the “lazy river.”


#18
There is no reason for this, silver copper and brass can all share
the same pickle with no issues. 

So long as you don’t introduce steel into the mix. Introducing steel
to a saturated pickling solution creates an electrical charge. Just
enough to copper plate any silver placed into it. Tres cool effect
to see as anyone who accidentally used the wrong tongs to remove a
piece from the pickle pot knows.

Michele


#19

Judy,

thanks for providing your citric acid pickle recipe.

I like to use the least harmful chemicals, and I’ll start looking
for dry citric acid. I understand it should be available in the “home
canning” section of grocery stores. Is this where you buy your
citric acid?

Thanks,
Mary Alexander


#20
So long as you don't introduce steel into the mix. Introducing
steel to a saturated pickling solution creates an electrical
charge. Just enough to copper plate any silver placed into it. 

It’s even more specific than that. The steel (any iron, other than
stainless) has to be in electrical contact with the silver or gold.
Doing that creates, in effect, a battery, and that’s where the
current to electroplate the copper from the solution to your silver
or gold comes from. If you’ve got a piece of silver hanging in your
pickle, and you drop a bit of steel also into the pickle but not in
contact with anything, then although the steel will dissolve, the
silver won’t be part of a current path, so it won’t be copper
plated. What happens instead is that as the steel dissolves, you’ll
see copper coming out of solutions, crystallizing on the dissolving
steel. If the pickle is saturated enough, and the steel thick
enough, eventually the copper covers the steel sufficiently that the
acid can no longer reach the steel, and the reaction stops. The
silver in the pickle will only be plated with copper if it is part of
the circuit, where it’s lower reactivity causes it to be
preferentially plated instead of the steel it’s in contact with,
which then dissolves unimpeded. The most common situation is putting
your silver into the pickle with tweezers made of steel, rather than
stainless steel (which usually is OK in the pickle). You can also see
this when you pickle something that had been tumbled in steel shot,
and there’s a bit of shot still stuck in the piece somewhere that you
didn’t notice. Or you can get this if you pickle something that’s got
a broken drill bit tip still imbedded in it… Another common
misconception is that once a bit of iron has contaminated the
pickle, it’s useless. That’s not true. Once the iron is dissolved, it
no longer can cause copper plating. If the pickle is truly saturated
with oxides, including copper, iron, and what all else, then perhaps
you may get some discoloration and surface films of crud on pickled
metal, but if your pickle is that far saturated, then it’s long past
time to replace it anyway.

Cheers
Peter