Patination of etched bimetal

I bought some copper/sterling bimetal from Reactive Metal Studios
(one of my favorite suppliers) and etched a design through the copper
to the sterling using ferric chloride. The design looks fine, but
whenever I use fluid that is supposed to patinate only the copper, to
highlight the design and make it stand out in comparison to the
sterlng, the fluid stains the silver as well. It doesn’t turn it as
dark as the copper, but it still turns the silver a muddy color, and
I can’t remove the patina from the silver without also removing it
from the copper.

This happens no matter what fluid I use – Brass, bronze & copper
oxidizer from Rio, or Baldwin’s Patina or Antique Patina from
Reactive (none of which are supposed to darken silver). If I use
silver black to darken the silver and not the copper, it still
darkens the copper somewhat, forcing me to buff the raised design.
Does anyone know what I could be doing wrong?

Thanks, Mona

Very curious Mona. I test every batch of Baldwin’s Patina on an
etched mokume-gane sheet. I have never seen this happen. My only
suggestion would be to depletion plate the piece. That is warm it
with the torch until a little color begins to appear on the sterling.
No flux. Then pickle it. Do this maybe four or five times. That
should pull the copper from the sterling and leave a more or less
fine silver surface on the sterling. Then use Baldwin’s following the
wet and warm instructions that came with it. Bill

Thank you, Bill, Deborah, Michele & Sarah
Reactive Metals Studio, Inc.

800/876-3434 928/634-3434 F928/634-6734


I can’t answer your specific question, but I might have a technique
to help you. You’ll have to see if this will work with your specific
patina or oxidizer – I know this works on silver.

If you use a Sharpie ink pen on the side/area you DON’T want to
oxidize, it will work as a mask. Oxidize as normal. Then remove the
ink using one of the household citrus cleaners formulated to remove
ink. Works like a charm on sterling and doesn’t harm the patina.

Tracy’s Treasures