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Removing patina


#1

Is there a chemical way to remove a black patina from sterling
silver ? I assume it is deliberately applied since it is
completely even and very black. It comes off easily with crocus
but this is not an option for the chain. I have tried pickle
(sulphuric) and warm sparex to no avail. TIA

Andy Parker, Agate House Lapidary
Ulverston, Cumbria, England
http://www.netcomuk.co.uk/~andyp


#2

Andy, I have always removed a black patina by heating the object
(chain) and placing it in a hot pickle bath. This really should
work. J.Z.Dule


#3

Andy; Re your problem withe the patina on s/s chain, if it’s
oxidation ( or sulphide ) I would think repeatedly heating and
quenching in Sparex should do it. If it’s an applied coating, a
good cleaning in the ultrasonic should work.

Jerry in Kodiak Alaska
(it snowed yesterday)


#4

Hi Andy, You can use a non ecologic way by using potassium
cyanide, it works very well. Just put your chain in the cyanide
salt dissolved in water in a glass beaker that you hold
(floating) in the ultrasonic cleaner. (stop breathing).

The way to make it ecologic, as I do, is to keep the same
solution for years in a good beaker with a good lid.
Vincent Guy Audette


#5

Andy, the black antique patina applied to sterling silver is a
silver/copper sulphide. Pickle or similar acids remove oxides,
but are innefective on sulphids. A soak in a dilute cyanide
solutions will take it off, or any of the commercially available
thiurea based cleaning solutions, such as Tarnex ™ or the
like. These dip cleaners are widely available, often even in
the grocery stores, and work quite well.

Peter Rowe


#6
Is there a chemical way to remove a black patina from sterling
silver ? --

G’day Andy; Yes. The black patina is probably silver sulphide,
or a similar compound. Though someone may have used gun
blue-black on it but it isn’t too likely. Firstly it must be
thoroughly clean and completely grease free. Wash well with a
softish brush - old tooth brush? - in hot detergent plus an
alkali; washing soda is good. Use rubber gloves - it isn’t good
for hands. Rinse well, keeping fingerprints off the work, then
heat (not boil) with 10% sulphuric (I personally prefer it to
sparex (sodium bisulphate); maybe because I have plenty. That
should do the job. Cheers,

        /\
       / /
      / /      Johnb@ts.co.nz
     / /__|\
    (_______)  In sunny temperate Mapua NZ -

Autumn’s here


#7

Andy, it may be black laquer. If so, try laquer thinner or
toluene. K.P.


#8

Sometimes “patina” is a spray on paint–some silver and gold
smiths use that instead of chemical patination. I have
experienced this, and soaking in paint remover, and then boiling
it out will help, but in the end you still have to work out the
crevices with tooth picks, etc…
----Barbara


#9

You might try heating and quenching in pickle. Or a strong
electro clean or stripping solution where the electricity is
flowing the reverse of platingmight loosen it up. If it’s baked
on enamel or an acid application, good luck.


#10

Dear Andy

In most cases the black patina is a so called “oxidation”,
although it is a sulphide layer. Ammonium, Potassimum and Sodium
Sulphide is easily removed by dipping the piece in “SilverClean”.
The more ridgid black patina is a selen sulphide. I normaly get
rid of it by repeatedly heating the piece and place it in a hot
pickle of 10 per cent sulphuric acid.

Regards
Niels, - from sunny (today) springtime Denmark, where the trees are
getting greener every day.


#11

Sometimes I have had oxidized pieces returned from various
galleries that no longer show any traces of the original
oxidation. Most of them have been left for too long in a simple
cleaning solution of hot water and washing soda used in
conjunction with a pierced aluminum plate. I believe there is an
exchange of ions that removes the sulfur from the surface of the
silver.

Steven Brixner - Jewelry Designer - San Diego CA USA
mailto:@Steven_Brixner4
http://home.att.net/~brixner


#12

I made an experimental piece for learning purposes–carved a line
drawing into a small piece of a sheet of wax, cut around it and cast
it in sterling. Hand polished and tumbled it, then I attempted to
color in the carved lines with Jax Black patina using a 5-hair paint
brush. It worked–mostly. What worked right looks like a woodcut
print.

But when I first started working, I accidentally “colored outside
the lines” with the patina, and it stained the shiny surface of the
piece in a few places. How can I remove the patina in those areas
without wrecking the polished surface and having to polish it all
over again?

–Kathy Johnson
Feathered Gems Pet Motif Jewelry
http://www.featheredgems.com


#13

Kathy, try using baking a baking soda paste and your thumb to remove
the color you do not want. If you have a hard buff and Zam or rouge
compound, you could try that. The trick is a hard surface that will
not move down into the recessed area.

Marilyn Smith