Trevor et al,
Pardon my changing the subject line on this thread, I hunted for the
original post but could not locate it in the archives. Never the
less, if I were to subject my Argentium Sterling to further heating
to increase the tarnish resistance, can I do it immediately after
precipitation hardening? Can I simply lower my oven temperature
from 270 C (525F) to the proper temperature for forming GeO. (Please
remind me what that is again I am thinking you said about 250C (~125
F), am I wrong?)
In light of this recent discovery I had another thought. If the GeO
that migrated to the surface could be chemically stripped without
disturbing the silver? Might it then be possible to depletion gild
the surface, or would the silver still be in solution with the
copper and so unable to “float”? That might be the case if the
Germanium will keep migrating up from the interior of the metal each
time you strip it off, until at last it is all gone & you are left
w/ conventional sterling. On the other hand if it behaves like Cu
does, and once a nice deposit of fine silver is in place it stops
coming to the surface, you might be able to treat that surface
molecular layer just as conventional silver. Then again, it might
not be worth all that trouble.
Marya
Columbus OH
... Never the less, if I were to subject my Argentium Sterling to
further heating to increase the tarnish resistance, can I do it
immediately after precipitation hardening?
My guess would be that if you’ve just precip hardened the Argentium
Sterling (AS) then the warming at the lower temps might be redundant.
Since the whole idea with the warming is to get the germanium to
migrate I pretty confident that the higher precip hardening temps
would have done all that and more.
On the other hand if you’ve precip hardened and needed to pickle
afterwards --sometimes necessary and sometimes not-- then I can see
where you might want to do the warming trick just in case.
... If the GeO that migrated to the surface could be chemically
stripped without disturbing the silver? ....
In theory I can see where you’re going with this but I for one have
no clue how you’d chem treat the AS to pull the germanium oxide off.
Another consideration is that germanium has been shown to migrate to
the surface from within the silver at room temperatures, albeit less
than happens at higher temps, so if you’re trying to get rid of the
germanium oxide you may well be fighting a losing battle. This begins
to sound to me a lot like using the wrong “tool” in the first place.
As much as it flies in the face of tradition I’d suggest skipping the
whole depletion gilding step. I’ve found AS to break more than a few
of the “traditions” that we have and hold regarding the use of regular
sterling silver so if I had the time and the inclination to
experiment I’d use the AS as is and see what happens.
I’m not sure of your reason for wanting to depletion gild the AS
–sorry, seem to have lost that somewhere-- but if it’s for something
like enameling you might be interested to hear that there are
unofficial reports that AS can be successfully enameled as is. I’m
afraid I can’t offer any references to back that up but I have heard
it discussed by the people in the know.
Another approach would be to simply use regular sterling in cases
where you felt it necessary to depletion gild. As far as hallmarking
goes sterling is sterling so mixing AS and regular sterling may well
be the reasonable approach.
Cheers,
Trevor F.
in Paris, The City of Light
Sorry, I apparently missed some discussion while I was teaching at
MAKER in California (which, by the way, was great fun—many of my
hydraulic press students did cooperative projects with the students
doing etching with Linda Threadgill in a neighboring workshop!)
Marya, if you have hardened the Argentium in the oven, no further
heating is necessary for increasing the tarnish resistance. The point
is that a bit of heating after polishing is a good idea.
The idea you mention of stripping the GeO from the surface does not
seem practical or desirable, since that would make the sterling NOT
tarnish resistant.
Cynthia Eid