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Yellow stains on sterling


#1

Does anyone know what causes sterling to turn yellow when you take
it out of the pickle and put it in neutralizer?


#2

Hi Pixie,

We had this issue, or a very similar one, where I study.

As second year students we mostly work in sterling and fine silver,
and after pickling we found that our silver was coming out with a
gold tint (this was a hint but we didn’t see it at first).

We thought that it might be a contaminated supply of sterling, but
our sterling was bought from several different manufacturers.

Our class is on a Wednesday… however the Tuesday class are a year
ahead of us and the same pickle they used was the same pickle we
used… they were pickling gold.

We changed the acid and all was fine.
Regards Charles A.


#3
We changed the acid and all was fine. 

Might have been something in the gold alloy, but rest assured it
wasn’t the gold. Pickle dissolves metal oxides. Gold doesn’t oxidize.
After heating, any oxides on a piece of gold are generally from
copper, not the gold. Just like with sterling silver. There will not
be ANY gold ions at all in the pickle, no matter how much gold you
pickle in it.

I’d guess, Charles, that your pickle was just getting too full of
copper, or had been contaminated with something else, perhaps iron,
tin, zinc, etc. Some gold alloys contain a bit of zinc, and white
golds may have nickel, and both of these would get traces into the
pickle in those cases. Gold itself couldn’t have been giving your
silver that yellow look. But whatever the cause, changing the pickle
for new would eliminate any contaminant causing problems.

Peter


#4
I'd guess, Charles, that your pickle was just getting too full of
copper, or had been contaminated with something else, perhaps
iron, tin, zinc, etc. Some gold alloys contain a bit of zinc, and
white golds may have nickel, and both of these would get traces
into the pickle in those cases. Gold itself couldn't have been
giving your silver that yellow look. But whatever the cause,
changing the pickle for new would eliminate any contaminant causing
problems. 

Thanks Peter,

It must have been something in the gold alloy, it was 18 carat (or
generally so), maybe zinc. When the pickle was just used for
sterling, there were no issues.

Could have been that the pickle was getting a bit used up… I’ll
have to do a few experiments :slight_smile:

Changing the pickle did the trick for us.

Regards Charles A.


#5

I have had problems with stains on my silver when others were using
the pickle for red brass (which of course contains copper).
Especially when they left their brass in there for some time.
Changing the pickle eliminated the problem.

Margaret