Post by -SP-Post by EddieHi all!
My customer wants to have "back" her silverchain, so is there some
(easy
Post by Eddieway) to remove gold plating from silverchain?
Yes, if you have the means, propane or other, tumbler etc, then just
burn the plating off, let it cool a little, pickle it, and then
shot-barrel it.
Get the chain to just 'under' cherry red, and follow the above.
Works for me.
This will work IF the chain was sterling silver with no additional plating, at
the time it was gold plated. many silver chains on the market are rhodium
plated to prevent tarnishing. One can gold plate such a chain, though often
the gold plate does not adhere so well or look so good. If your customer's
gold plated silver chain was ever rhodium plated, and if some or all of that
plating remained on the chain when it was then gold plated, heating the chain
not only won't "burn off" the gold plating, but will cause the rhodium plated
layer to bubble up. When that happens, it looks absolutely terrible, and is
almost impossible to repair.
"burning off" the gold plating isn't exactly what happens. At elevated
temperatures, the thin gold layer simply dissipates into the silver, becoming
invisible. In fact, if gold is plated directly over silver without any
intermediate underplating, this will happen on it's own, at room temperature,
over a period of perhaps years, especially if the gold plated layer is quite
thin. Like this, at room temp, the color often doesn't completely disappear,
but the plated layer ends up looking paler and paler, eventually being just a
slight yellow tint. With heating, the gold dissipates further into the silver,
and is no longer visible.
When one gold plates silver, knowing the above, it's sometimes good practice to
isolate the silver from the gold layer. Commonly, this can be done with an
intermediate plated layer of copper, or of nickle, or often, a combination of
both. This is the same then, as is done prior to rhodium plating silver. If
the gold plate on the chain was put on wth this type of nickel underplate, then
heating will also not burn it off, but can, as with rhodium, just make a mess.
With larger heavier chains, it might be just easiest to buff the chain, if the
style is one where a soft bristle brush can get to most of the surface area.
That can safely remove the gold plating from exposed areas, without bubbling
underplated layers. However, it doesn't remove all the gold, as recessed
areas, such as inside surfaces of the links, won't get buffed. Tumbling can
sometimes take some of it off too.
or, another simple fix is to silver plate the chain right over the gold. Won't
last forever, but might last a goodly long time, and can always be redone.
This avoids potential problems with bubbling up nickel or rhodium underplates.
And so does SP's final suggestion. Buy another chain. Given the time involved
to fuss with this, how much more expensive, if at all, will a new chain be?
A couple other methods deserve mention, just in the interest of completeness.
One method of removing the gold plating is electrostripping. The best
electrostripping solutions for gold are cyanide based, however, so this isn't
something to use unless you're quite familier with the needed safety
precautions. With a thin plated layer, just soaking for a time in a cyanide
solution will dissolve the gold, even without electric current. In both these
cases, be aware that once you've dissolved the gold layer, the cyanide is just
as happy dissolving the silver too, so monitor the activity and remove the
chain as soon as the gold is gone, or you'll be making the chain thinner.
And, related to both electrostripping and just cyanide soaking, "bombing" will
remove a thing gold plate from silver just fine. This has the advantage over
electrostripping that it does not remove more from external exposed surfaces
than from internal recessed ones. Bombing removes it evenly from everything.
You'll probably have to do it a couple times, since if the gold layer is thick
enough, the bombing action will initially tend to redeposit some of the gold
back onto the silver, but after a couple cycles, this won't happen. As with
the other cyanide processes, this will also remove some silver, so pay
attention. And as with the others, bombing is not something to do unless you
know the proper methods, have the right equipment to do it safely, and can
properly dispose of the used solutions. Chances are, if you've come to this
group for advice on this, you probably don't yet have any of those assets, and
for a single chain, it won't be worth the expense to learn it and acquire the
needed equipment.
And one final possibility. Aqua regia (3 parts HCl to one part Nitric acid)
will quickly dissolve gold. When it reaches the silver, however, it tends to
stop actively removing metal when the silver surface forms a skin of silver
chloride that slows or prevents further attack. You'd want to closely watch
the process and remove the chain once the gold is gone, since the AR will still
slowly be attacking the chain. When you're done with this, you'd have no gold
left on the chain, but the silver surface would be dull and smutty grey/white.
You then toss the chain in a tumbler with steel shot, or better, a magnetic
tumbler, and it would brighten right up again.
Somewhere in all this, is likely a good suggestion for you. My guess is that
the new chain will be the best solution.
Peter