One word…DON’T! it immediately makes the gold much more harder to
set stones in, bright-cutting is almost impossible…So folks if you
have to do a “fast” cast prior to the end of this
"fun-season."…what’s a few more minutes of the gold returning to
the normal room temperature?
If you remove the hot flask out of the centrifuge and dunk it
quickly into a water bath…the result is “hard, white gold”…you
must either let the flask sit in a cooling down casting oven or just
leave it on a shelf to cool down…I just delivered a “hard” white
gold pin with 20 pave’d stones and I asked my client what
happened?..“I did a fast water cool down”…:>(…
One word...DON'T! it immediately makes the gold much more harder
to set stones in, bright-cutting is almost impossible
I have always had a concern that if left too long to cool a white
gold casting would have too large a grain growth. Is this unfounded?
If it were quenched while still hot (not right after casting, but
allowing the flask to cool 5-10 minutes), would it be wise to anneal
the cast item before work is done on it?
I let white gold air cool when I have annealed it. Any comments are
appreciated.
I was taught to wait until the button loses it’s red color, then
quench in alcohol. The process seems to work very well, but now you
have me questioning my processes.
The white gold alloy I use is from Hoover and Strong and they
recommend letting the flask cool until the button is no longer red.
They call this “Black Heat” approx. 840-930 Degrees F. Then
quenching in water. I have a resprator mask to wear so I’m not
sucking up any silicon. I use small flaskes so on average, it only
takes a moment to get down to “Black Heat”. They also say that if
quenched too soon it will make the gold harder to work.
IMO the problem is that there are variables like gold weight, flask
size and thickness/thinness of the items being cast that make it
hard to know just when to quench.
Franklin, When I work with nickel white golds, I anneal them and
allow them to cool to “black heat”: after the red has disappeared,
about 600 to 800 degrees. I then quench them in denatured alcohol
which provides a relatively slow and gentle quench. It helps
immensely. It also blasts a lot of the oxide off the surface and you
can go directly to the mill with no ill effects to the rolls. (Be
cautious since alcohol is flammable. Keep it away from the torch and
NEVER quench red hot metal. I IN NO WAY ASSUME ANY RESPONSIBILITY
FOR THE MISUSE OF THIS TECHNIQUE…)
I never quench ingots, which are castings, after pouring or until I
have reduced (rolled or forged) them by at least 50%. It is hard to
evenly quench a large, heavy object without having stresses that
resolve themselves in cracks and tears.
It is oddly counterintuitive that quenching white gold makes it
harder (the crack/stress issue not withstanding), since the smaller
the crystal growth and size the more malleable, dense and workable
the alloy usually is. But with nickel white golds (the Devil’s
Metal) all bets-- and logic-- are off.
I can tell you that white gold has a short smallish window for
optimal quench. Quenching too early or too late causes brittleness. I
suggest a quench when either all the red is gone from the button or
at 900 F. if you can measure the flask. This varies by alloy-So work
up your own timing for your flask mass (big ones cool slowly) and
your nickel white alloy. I believe Pd white to be more forgiving. So
not too fast not too long…
In January I hope to release a DVD on working white gold. I hope
to cover all this stuff… Color theory, casting, fabricating, alloy
selection, the works. Would anyone care to chime in on this one? I
can include Orchid wisdom in the DVD, full generous credit of course.
I have always had a concern that if left too long to cool a
white gold casting would have too large a grain growth. Is this
unfounded? If it were quenched while still hot (not right after
casting, but allowing the flask to cool 5-10 minutes), would it be
wise to anneal the cast item before work is done on it? I let white
gold air cool when I have annealed it. Any comments are
appreciated.
Whose alloy? what karat? Each alloy will have its own requirements
for for annealing temperatures and times and cooling rates. Check
with your alloy supplier for the correct procedure for your
particular alloy.
Also get Stuller’s new Metals catalog it has a great section on
precious metal metallurgy and covers the hows and why’s on a wide
variety of topics. My only complaint is that they don’t provide
specific on their alloys. As far as I can tell the
is generic and the most detailed info is relating to
yellow golds so I hope they will expand this section with more info
on colored golds , silver and platinum. But even with those
complaints it is a very useful batch of
Jim
Jim Binnion
James Binnion Metal Arts
Phone (360) 756-6550
Toll Free (877) 408 7287
Fax (360) 756-2160
@James_Binnion
Member of the Better Business Bureau
I never quench ingots, which are castings, after pouring or
until I have reduced (rolled or forged) them by at least 50%. It
is hard to evenly quench a large, heavy object without having
stresses that resolve themselves in cracks and tears.
And besides, when you cast an ingot, you’re casting into a mold that
is likely only around 400 to 500 degrees or so, and possibly
considerably cooler depending on your method. So just in the ingot
mold, it’s already cooling quite rapidly enough. By the time you’ve
extracted the ingot from the mold, quenching is pretty much just a
matter of cooling it enough of that last bit of heat so you can
pick it up in your fingers.