Getting a good contrast on a bi metal pattern

Dear all,

I am having trouble getting a good contrast on a pattern I made
using red gold (18k) and sterling silver, with lime sulphur as a
patinating agent.

To make the pattern I put together a bi metal by hard (silver)
soldering a 1mm thick piece of 18k red gold to a thick silver back
and then rolled it down to the point where the gold is probably just
about 0.1mm thick, so lots of annealing and a few resolders to keep
the silver back plate of sufficient thickness. I then stamped a
pattern into the sheet and filed off the gold which had not been
punched down, then by rolling brought the pattern to the surface, so
a sort of very simple soldered mokume approach.

After finishing to 400 grit, taking care to get all of the fine gold
off of the surface of the red gold so that it’s true colour was
there, I carefully cleaned it up and fumed it in lime sulphur, hoping
for a lustrous black silver framing a fiery red gold pattern. Alas,
the whole thing looks dull and it is almost easier to see the pattern
before patination. My silver also seems to be misbehaving, with some
just not taking the patina even after recleaning (firestain could be
an issue here). A piece I did at the same time in 18k yellow seems to
have worked better (but not quite as well as I had hoped), so it is
not a cleaning issue. Any thoughts on how sort this one out (apart,
of course, from start with a different combination of metals :-)).

Chris Penner

It sounds to me that your two metals now have one contiguous
surface. Completely smooth. If I understood your description
correctly. Perhaps cut a dividing line between your metals. Use a
graver after fabrication or fabricate it in a way that ‘builds in’ a
small groove of sorts. This should add definition if it works with
your design concept.

You may have refined the surface too much. I think that more of a
satin finish might work better.