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Red gold pickle needed


#1

Orchidians, Does anyone out there in cyberspace have a formula that
will bring out the red in red gold? Most pickles attack the copper
oxide, and this tends to leave the gold very yellow. I used to know
a chemical dip that would bring out the copper, but I can’t remember
what it was.

HELP!
Doug Zaruba


#2

Fellow Orchidians: Does anyone out there is cyberspace have a formula
for a pickle that will bring out the copper in red gold? I’m
assembling a tri-color reticulated band, so I’m looking for something
that will not affect the other colors. That leaves out copper plating
with old pickle…

HELP.
Doug Zaruba


#3

Doug hello! Your tri-gold project may get the results you want using a
10% Nitric dip. It has been years since I have used acids for
anything other than gold testing. Looks like you have a good reason.
I can guarantee you Nitric will affect your red gold at a faster rate
than the other alloys. Your immersion time depends a lot on the size
(volume) of your piece. I would anticipate 15 to 20 seconds and
rinse. Your results should be noticeable and possibly satisfactory.Be
prepared for your solder areas to react as well. Nitric really chows
down on solder. Good luck! Tim


#4

Doug, I do not know of any chemical means that will bring out the
copper. What I would do is use a micrograver brand or other miniature
sand blaster with 240 grit or finer aluminum oxide abrasive to
lightly cut back the surface then use either very fine glass beads
to put a matte finish or into a magnetic tumbler for a shiny finish.
The micro graver allows very precise removal of the surface layer and
you can easily protect areas that you do not want to be affected with
masking tape.

Jim


@jbin
James Binnion Metal Arts
4701 San Leandro St #18
Oakland, CA 94601
510-533-5108


#5

Tim, I routinely immerse tri-color gold plus silver into 50% nitric
solution. There is no visible effect on any of the golds( of corse it
etches the silver which is why I do it) Gold alloys with more than
25% gold content are not readily affected by nitric alone.

Jim


@jbin
James Binnion Metal Arts
4701 San Leandro St #18
Oakland, CA 94601
510-533-5108


#6

Hi, Doug- Regarding the tricolor reticulated band, is it your plan to
depletion gild the red gold and then reticulate? And then remove the
depletion-gilt layer to reveal the red gold underneath? I think it is
unlikely that you would be able to expose the red gold by chemical
means, as gold tends to be less rather than more soluble than copper.
You could abrade the high-karat gold from the surface, but if the
surface is reticulated, getting into all of the folds of the
reticulation may be a real hassle. Perhaps you could reticulate
silver, make a mold of it, and then cast red gold with a reticulated
pattern? That should eliminate the need to remove the yellow gold
from the surface-

Lee Einer


#7

Hi Doug,

hope all is well with you and yours, been a while since I’ve seen
you… In the depletion gilding paper on ganoksin are some bits
related to this:

http://www.ganoksin.com/borisat/nenam/depletio.htm

Mixtures of salts have also been developed which attack one of the
constituent metals in the three part alloy preferentially, so that if
for example silver is preferentially removed the resulting surface may
have the reddish tones of copper to it. One can then adjust an alloy’s
addition metal content and hence control it’s color after having mixed
it when alloying. Note that one might consider which starting alloy
would be most advantageous for working with. Copper rich alloys are
more easily attacked by acids than silver rich ones and might then be
more useful for such surface color adjustment. High carat golds in
general depletion gild better than lower carat ones (Brepohl, p 315).
The work is dipped in the solution or it is brushed on to the work,
and I assume then heated. The color of the surface may also be
adjusted by pickling (etching) in HCl, H2SO4 or acetic acid. The
mixtures described include:

          To obtain a yellow

          6 parts Potassium Nitrate KNO3
          2 parts Ferrous sulfate
          1 part Zinc sulfate (this is a concentrated mixture)

          To obtain a reddish-green

          9 parts Copper Acetate
          3 parts Ferrous Sulfate
          3 parts Potassium Nitrate
          3 parts Ammonium Chloride NH4Cl
          30 parts Water

          To obtain a green

          12 parts potassium Nitrate
          4 parts Ferrous Sulfate
          2 parts Zinc Sulfate
          2 parts Alum
          20 parts Water
          (Ganzenm�ller, p404)

best
Charles

Charles Lewton-Brain
Box 1624, Ste M, Calgary, Alberta, T2P 2L7, Canada

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