As a chemist, perhaps I could offer a bit more advice on removing
mercury. Mercury evaporates a little below 400C and if you put it in
a domestic oven for a while you may be able to get rid of it that way
- but the opals probably won’t like it. Unsetting the stones is
probably the safest way. However Mercury is soluble in nitric acid
and if your gold is a relatively high grade you could try immersing
the affected areas in, say 10% nitric acid - which again I’d keep off
the stones. I suspect this might attack 9ct but 18ct would probably
be OK. The mercury will wear off/evaporate off eventually (weeks I
think) if you leave it alone. You will have to repolish as the
amalgam attachs the gold.
A customer of mine is a chemistry teacher. He spilled mercury on
his 14kt yellow gold wedding ring he just bought from me less than
6 months ago. He brought it to me in a zip loc bag. Are there
any precautions I should take with this stuff? How do you
reccomend I remove it? I was going to rubber wheel it off.
Hi Poppy, Mecanical removal of the mercury is not the best way. When
mercury gets onto gold it amalgamates with it (dissolves into the
gold), so it can get quite deep into the metal. Probably the best way
to deal with it is to heat the ring at a fairly low heat for a long
time. In the old days, there was a process called ‘mercury or fire
gilding’ in which fine gold was dissolved in a little mercury to make
a stiff paste which was then brushed onto metal such as brass with a
stiff brush. this was then heated gently over a charcoal fire until
all the mercury had been driven off. A final burnishing gave the
really beautiful deep gold surface I regularly see on antique watch
movements. Needless to say, most of the people who carried out this
trade went mad and died early (the term ‘mad as a hatter’ originated
from a similar process where mercury was used in the making of felt
hats). So, if you have an outdoor barbeque, you may like to try
heating the ring on this gently for a few hours…
Ian W. Wright
We have had a number of mercury contaminated problems.
Our first problem with mercury on a ring gave puzzled us quite a bit
until we discovered it was mercury. We tried polishing a small area
and this would remove the mercury for a while but the ring would turn
white again as adjacent mercury flowed back over!
Another was a customer who returned a chain following a repair we
had done for her. The 9ct gold chain had turned to “silver” she said!
What had we done to it? Upon examination with a x10 loupe you could
see the surface was fluid - the mercury could be wiped off for a
moment and would then flow over again.
But we did not have a problem with mercury in our workshop so the
mystery deepened - it was, of course our fault. We would have to
replace her chain.
A few days later the owner came to tell us that her daughter had
broken a mercury thermometer in the drawer that she kept her
jewellery and was afraid to tell her!
The chain being a fine Prince of Wales link was wrecked, the mercury
had eaten right through it and it eventually crumbled.
A dental nurse came in once with her wedding ring turned white. The
fact that she worked for a dentist gave us a clue immediately -
dental amalgam (silver and mercury). We removed the mercury by
heating in a fume cupboard.
One thing we have learned is that any gold turning white must be
handled with extreme suspicion. We had handled and polished mercury