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Revisiting enamelling on Argentium


#1

Trying to enamel the concave surface of a slightly domed piece of 24
gauge Argentium 925. about 30 mm in diameter.

Enamelling ==> 1450 degrees F for 2 mins, enamel flows fine and
seems to be OK.

But when the Argentium totally cools to room temperature, the entire
piece of enamel pops off the surface of the Argentium - a perfect
mold of the concave domed surface!

Cleaned piece again, pickled, heated to 250 degrees F for 10 mins
(as someone recommended) to build up surface of germanium ==>same
result - enamel pops off the surface when piece reaches room
temperature again.

Would Argentium 970 work any better, or do I just go back to regular
old silveri

Any suggestions most welcome.
Jon


#2

Hi Jon,

I’ll just leap right in (like a fool perhaps). Two concepts come to
mind: differing expansion coefficients between the glass and the
alloy and oxidation. Thompson Enamels produces a publication known
as Glass on Metal. Articles, written by the then president Woodrow
Carpenter, in the early issues are very intersting in explaining the
chemistry and physics of the enameling process. Perhaps the new
workbook (I have not yet bought it) perhaps does the same thing and
would be of interest to you.

I recall reading that during the heating and thus fusing process the
metal surface oxidises (this includes both gold and silver, just to
a lesser extent than copper) and that the oxide year diffuses into
the molten enamel. This process acts, in part, as the “glue” that
binds the glass to the metal.

So, just maybe, you have two physical processes working against you.
My question is why not work with fine silver; is it too soft for the
ideas that you have in mindi

David


#3

the entire piece of enamel pops off the surface of the Argentium

Here’s something to try: get 6-8 firebricks and stack them to make a
little “warming hut” with a roof. Take your piece on it’s trivet and
put all into the brick house, put a brick across the opening. This
often protects items with steep sides from flicking the enamel off
by protecting somewhat from thermal shock. You could also rough up
the Argentium surface with a glass brush. I’ve never had the whole
sheet of enamel come off except once when my surface wasn’t as clean
as it should have been (this was with copper). You might also try
with 20 gauge Argentium.

Donna in VA


#4

Maybe I am getting stodgy, but am content to stick with fine silver
for enameling jewelry, and copper for other items. . Much as I have
been tempted to try argentium for enameling, I have decided just to
stick with fine silver. Also I use 18 gauge for flat pieces, but have
gone as thin as 30 gauge when the piece was domed. So far, no
problems with popping off. Furthermore I watch my COE’S carefully, so
that I don’t have a problem there Alma, in the gorgeous northwest,
where spring is making a fantastic appearance. Everything bursting
into bloom.


#5

Jon,

Would Argentium 970 work any better, or do I just go back to
regular old silver 

I don’t know if you’ve heard but The Worshipful Company of Goldsmiths
(http://www.thegoldsmiths.co.uk) has published at least one report –
actually I think there’s been a second – on just this topic. Their
conclusion was that yes, Argentium Silver (AS) can be enamelled but
there may be some color shifting in the process. If you are so
inclined see the following posts on my AS blog for further info:

http://touchmetal.com/blog/2005/11/enamelling-on-germanium-silver.html
http://touchmetal.com/blog/2005/11/enamelling-lapidary-journal.html
http://touchmetal.com/blog/2006/03/enamelling-some-follow-up.html

That said I believe it has more or less been acknowledged that AS
925 is not ideal for enamelling purposes (because of the color
shifting) and that Peter Johns intends to address that as part of the
ongoing alloy development.

I don’t know of any test results for enamelling on AS 975.

Cheers,
Trevor F.
in The City of Light
Visit TouchMetal.com at http://www.touchmetal.com


#6

Hi Jon,

My friends that successfully enameled on AS 925 found that it worked
best if there is NOT a germanium oxide surface. Better adherence
occurred when the AS was freshly abraded to removed the oxide prior
to enameling. (This makes sense if you think about how enamel works
really well on copper, and that abrasion exposes the Silver / copper
/ germanium alloy.)

I suspect that AS970 will be better for enameling, but have not
heard from anyone who has tried it yet. Please do share your results
when you try it!

Cynthia Eid
http://www.cynthiaeid.com


#7

This topic has come up a number of times and I believe Trevor has
mentioned that they are working on the possibilities. The problem in
the past has been the melting temp of AS is too close to melting
temp of lead based enamels.

And yes, I have had them pop right off sometimes even providing me
with a “lovely :>) crack down the middle”.

So, I will sit and watch and hope someone comes up with a solution,
but meanwhile I will continue to use my reliable fine silver as Alma
does.

jennifer friedman
http://www.jenniferfriedmanstudio.com


#8

Problem solved I think.

I tried this:

  1. pickled the domed 30 mm Argentium 925 piece for 15 mins at 140
    degrees F in citric acid pickle.

  2. sanded the surface to be enamelled with 220 grit emery paper (to
    try to remove germanium layer)

  3. sifted on Thompson opaque enamel

  4. in kiln at 1450 degrees F for 2 mins

  5. repeated steps 3. and 4. two more times (for 3 coats of enamel)

Worked fine - enamel seemed to “stick”, has not popped off (yet).

So maybe the key here for enamelling Argentium 925 is to sand off
the germanium layeri Or maybe I was just lucky second time aroundi

But I have now enamelled 3 pieces of Argentium using the above
technique, and none have popped off.

Jon


#9

Jon,

I do not think it is a fluke. Your experience is the same as the
other enamelists that I have spoken to.

Cynthia
Www.cynthiaeid.com


#10

All,

sanded the surface to be enamelled with 220 grit emery paper (to
try to remove germanium layer) So maybe the key here for enamelling
Argentium 925 is to sand off the germanium. 

Maybe I’m missing something here…but, why use AS in enameling
and then remove the A? Just use fine silver or deplete some 925?

Cheers from Don in SOFL


#11

sanded the surface to be enamelled with 220 grit emery paper (to
try to remove germanium layer) So maybe the key here for
enamelling Argentium 925 is to sand off the germanium.

Maybe I'm missing something here.....but, why use AS in enameling
and then remove the A? Just use fine silver or deplete some 925? 

And what I’m wondering is why you want to cover any expensive silver
product with an opaque enamel? You normally use copper with opaques
and if wanting a silver edge, you can bezel set the piece like a
stone.

Donna in VA