I don’t know if anyone can answer this query, but I thought it worth
the time to ask. I’ve been pounding out a bunch of chain maille
bracelets in both copper and sterling for a couple upcoming shows,
and popped about six of each into my rotary tumbler yesterday before
heading out to run some errands.
Came back about two hours later to retrieve them and discovered that
all the copper color had been “washed out” from all the copper
bracelets!!! I had a similar experience with some 16 gauge copper
clasps I’d made a month or so ago; but the copper I had used then was
left over from a small spool I’d gotten at a hardware store a couple
years ago and was just trying to use up. My thought at the time was
that perhaps the copper sold in hardware stores was of a different
composition than the large spools I purchased from Rio. Apparently
not.
As I always tumble my copper rings for a bit after I cut them, I
didn’t think anything of leaving the bracelets in for the same length
of time as the sterling versions. Though it seems there’s a critical
point for “copper washout”.
Can anyone explain to me what I now have? Are my bracelets still
100% copper? Is copper even 100% copper, or have I been purchasing an
alloy?? I would have thought that copper color went all the way
through! Will they still tarnish in time?
I can’t afford NOT to put these bracelets out, as I put a lot of
time and effort into making them, so will probably tag them as
"tumbled copper". But I’d like to have a story, other than stupidity,
to relate to anyone picking one up and wondering if it’s sterling
(when placed next to a sterling bracelet, you can tell the metal is
definitely not sterling, but the bracelets are now a silver tone). I
can probably put a spin on the whole “tumbled copper” story, but it’d
be nice to have the metallurgical story as back up.
Many thanks!
Karan, who once again learns the hard way! : )
Earlier today, I sent an inquiry to Orchid… and also to The Copper
Development Association:
An important piece I neglected to include in my Orchid post, but
included to The Copper Development Association
(http://www.copper.org) ) was that my tumbler was full of water,
ammonia and Dawn dishwashing liquid… and, apparently, therein lies
the answer! Color me surprised:
You apparently plated silver on to the copper items. Both copper
and silver are nobel metals. Usually copper will be the more
nobel metal in a dissimilar metal couple, e.g., copper (Cu) and
iron (Fe), so that the copper would plate out onto the Fe. This
known as the "cementation" process, an auto plating process. The
typical experiment is to place a nail (Fe) into a soultion of
copper sulfate. Copper plates on to the nail.
Since silver (Ag) is MORE nobel than Cu the Ag plated out on to
the Cu, the water and ammonia being the electrolyte.
If you put both silver and copper in the tumbler at the same, then
this is expected: there will be a cathodic reaction with two
different metals in an electrolyte, which could be from the media you
used in your tumbler. A metal with lower standard electrode potential
will give up an electron to one with higher potential. Steel media
would therefore plate out on silver and copper, and all you need to
complete the reaction is to immerse the material in an electrolyte
(water with almost any kind of salt). Even an abrasive may contribute
to this, but all the function requires is the two differing metals
and the electrolyte. There may be other functions at work here; need
to know exactly what is in your tumbler.
You apparently plated silver on to the copper items. Both copper and
silver are nobel metals.
Just as a point of - the rest of the article about
plating is true, but neither copper nor silver is a “nobel” metal.
I’m assuming they would mean “noble”. Gold and the much of the
platinum group are noble metals, and that’s all. Silver and copper
are transition metals, but that’s not saying much, in this case.
Karan, I have two questions: (1) are you sure that your original
copper was 100% copper, or might it only have been copper-plated (in
which case, the silvery color is that of the underlying alloy)?; (2)
just out of curiosity, why did you have ammonia in your tumbling
liquid, instead of just the Dawn detergent?
actually silver is a noble metal: it is highly resistant to
corrosion. In physics, the definition of a noble metal is one that
has all the electrons in the d-shell filled. Silver fits this
definition too. Silver is in a transition series but then so is gold.
Purity is highly imporntant for copper to be usefull for electrical
wire since even one percent of other metals greatly affects its
electrical conductivity, Electrical wire is likely to bee at
least 99.9% pure, i doubt if they intentionaly add anything at
all, im not an expert but you have probably just burnished traces
of other metal into the surface of your copper,
Just as a point of - the rest of the article about
plating is true, but neither copper nor silver is a "nobel" metal.
I'm assuming they would mean "noble". Gold and the much of the
platinum group are noble metals, and that's all. Silver and copper
are transition metals, but that's not saying much, in this case.
In the electrolytic series the metals are referred to as be more or
less noble in regards to where they place in the series so therefore
silver is more noble than iron iron is more noble than zinc etc. Both
silver and copper are fairly high on the cathodic end of the series
so they can be referred to as nobel metals.
Jim
James Binnion @James_Binnion
James Binnion Metal Arts
actually silver is a noble metal: it is highly resistant to
corrosion. In physics, the definition of a noble metal is one that
has all the electrons in the d-shell filled. Silver fits this
definition too. Silver is in a transition series but then so is
I don’t consider it that important to get into it, but I was using
and thinking of the classical definition - by that they are not. But
if modern science says they are (I prefer the classics, myself) then
so be it.
First: Noble metal is not a scientific definition, it is a group of
metals which resist corrosion under normal conditions. “Highly
resistant” is scientifically vague. Some definitions include Silver,
the others not.
Silver easily dissolves in Nitric acid. It is also easily combines
with Sulfur and Chlorine, but these are not normal conditions. If we
change the definition to “those which do not rust” than Aluminum
becomes noble, but that is also not true, since Aluminum oxidized
even faster that iron.
So you see, noble metal is a hard thing to define. About “d-shell
been filled”. That is a left over from the days of the Bohr Model of
Atom.
Now we have better understanding of structure of the matter. To
those who interested I refer to many books on Quantum Theory.
I can't afford NOT to put these bracelets out, as I put a lot of
time and effort into making them, so will probably tag them as
"tumbled copper".
So it seems pretty likely that your bracelets are coated with either
steel or silver…
If silver, you should be able to remove it by putting them into
nitric acid briefly (not for long, if there is any silver solder
involved) or by tumbling them in a slightly abrasive medium. Has
this happened when there was no silver present, and when your
solution is fresh and clean?
Alternatively, you could patina the bracelets. After liver of
sulfur, they shouldn’t look too different from regular copper.
Thanks for all the input folks… when I think about what happened
with my copper bracelets, it’s actually pretty cool. However, I
didn’t get a lot of positive feedback during the past four days and
three shows I did, so I’m inclined to try to return them to their
coppery brilliance. I’m getting mixed suggestions from folks,
however. What I intend to try is just putting them back in the
tumbler with just water and Dawn (one individual suggested adding
some kind of pool cleaning chemical to the tumbler… ei yi yi). And
to answer Judy’s question, I used to use just water and ammonia, a
suggestion made to me by an instructor at an Arts Center I used to
attend (and she got it from a local jeweler/retailer), but added
Dawn to the mix after reading posts on a wire jewelry forum. I
occasionally still use just water and ammonia, or just water and
Dawn. It just happened that I had ammonia in this mix, which allowed
for the silver plating.
I don't consider it that important to get into it, but I was using
and thinking of the classical definition - by that they are not.
But if modern science says they are (I prefer the classics, myself)
then so be it.
Yeah but the classics say that you can test diamond by hitting it
with a sledge hammer (kinda tempting sometimes mind you…), Pliny
the Elder has a lot to answer for in some regards. grins