The original person who started this thread asked about Argentium.
(not to get major suppliers to try to sell their products)
I cast Argentium Sterling regularly two to three times a
week…here is what I do.
I am usually casting 2 1/2 inch flasks, sometimes 4 inch flasks (all
custom work, small items)
- centrifugal casting - torch (propane & oxygen) to melt and I use a
somewhat hotter flame than I use for regular silver (for regular
silver the flame I use is somewhat reducing, I use more oxygen in the
flame when casting Argentium) The usual amount I cast is from 10 to
60 grams in a flask
i) I find that I need a mix of new grain to old buttons of 60% new
and 40% old (50/50 shows some signs of a poorer cast on occasions,
but not always) I make very sure the old material is very clean
ii) I coat the material to be cast with boric acid dissolved in
alcohol, then burn off the alcohol, I use no other flux The boric
acid solution is about 30 – 40 % saturated
iii) I am careful to not over heat the metal (molten Argentium looks
different from molten sterling) I cast shortly after the metal has
become fully melted. The Argentium 935 pro appears to have a large
slush area. It does not roll as easily like molten sterling silver. I
notice that I have a few bits still adhered to the flask after
iv) the flask temperature I use is slightly higher than what I use
for regular sterling (1100f for very fine items down to 850f for
v) I always let the flask cool to about 250f - 300f or right to room
temperature and I break out the cast, I do not quench. (I have
quenched hot flasks in water, the casting will crack!)
vi) The just cast material is very white. I ultrasonic clean off
investment for a few minutes only, pickle in hot pickle for a few
minutes, then ultrasonic again about one minute.
My castings are always free of porosity, never have surface pits
from contamination and work and polish well. I very often fuse (weld)
pieces together and will use Argentium hard solder and medium only. I
have never had a need to use easy solder.
I always heat treat in a small kiln holding the temperature at about
500 – 550F for an hour.
The finished cast jewellery is very white in colour, reasonably hard
and has a very good polish. Never has fire scale been a problem and
when doing torch work, I do not coat with anything at all.
My customers tell me that their items remain bright and they are
pleased. I have a little bit of evidence that those that can turn
sterling silver black when worn have much less of an issue with the
Argentium sterling silver.
I cannot comment about any of the other sterling silver alloys as I
am not at all familiar with them and do not wish to suggest that
Argentium is superior to any of these alloys.
I trust that I have been helpful.
Regards to all.