The formula for sheet and wire is ever so slightly different than
the casting grain, but I have had no problems with casting with all
my scrap as I am not adding solder. These were cast in July, 2012.
Tarnish resistance seems very similar in each piece. They are left
in a window sill to leave in the atmosphere to see what the tarnish
resistance will be with time.
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I would like to share a little more info that may help. These are
the processes we use here at Rio Grande and we get great results. I
think this would be a good starting point, but all shops are
different and result vary based on casting equipment, types of ovens
etc.
the temperatures at which hardening occurs, and the procedures
needed, are given in my handouts, which are on my website www. cynthiaeid.com under FAQs, and on the Argentium Facebook group.
There are also technical guides, at the company website, under
Resources.
The idea of simply letting it cool to hardening temperature, and
holding it there, is interesting----Iâm not sure that anyone has
tried that.
The generally accepted procedure is to heat to 580 degrees F for an
hour or so. Higher is NOT better.
The lowest temp that it works is 350 F, where it takes about 2
hours. For temperatures in betweenâextrapolate or take a rough
guess. the time is not critical, though it needs to be long enough,
yet not overly long. More than 3 hours could cause problems.
I usually just harden the piece at whatever state it is when it is
finished. It generally is better to do the hardening at the end,
because in addition to hardening, doing the procedure after all the
abrasive finishing processes will increase the tarnish resistance.
Hardening immediately after casting will mean that youâll need to
have a second procedure at after finishing to increase the tarnish
resistance. (the ideal temp for that is 250F for two hours, but any
heat is helpful.) Best wishes, Cindy
We want to do the initial heat-treatment to harden the castings.
Can the casting be put back in the kiln after removing the
investment? It may still be as hot as 800F in there. At what temp
does it actually begin to heat-harden? Does it need to be left
until it reaches 500F and *then* be held an hour?
The best treatment is to heat to annealing temperature and then
quench followed by the aging treatment at about 500F. Otherwise let
cool and then reheat at 500. Putting it in the kiln at 800F will
over-age it and not give you the hardening effect.
