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Vacuum casting temperatures

Hi Daniel, Casting is a mystic art. You mentioned that you vacuum
cast into a 1150 to 1300 degree flask. I have poured up to 20
ounces of sterling in one shot. My casting walls run between two and
three mills thick and not as involved as filigree work. My metal
temp is 1860 degrees and the flask temp is 860 degrees. I once had
a fellow caster tell me that my flask temp was too low. He
suggested using a flask temperature of 1050 degrees. I tried it and
the sprue button absorbed oxygen and blew up line a balloon. I cut
it open with a band saw and the insides looked like a sponge. I find
if I go hotter on either the metal or flask I get porosity.
Probably has to do with the thickness of my projects. I have blown
out a few flask in my time. I was told to leave a 1/4 inch for
every inch of diameter of the flask. I like your idea better. Once
I did not pay attention and poured silver into a ruptured flask.
The silver flowed out of the flask and melted through the aluminum
vacuum plate. Boy what a mess. I would love to visit your studio if
I ever get out your way.

Thanks for all your inputs. Your Orchid Friend Lee

Hi Lee, You would be more than welcome should you come to these parts
of the world :slight_smile: I actually think of casting more as a science In
the sense that almost anything can be cast… It’s just a matter of
figuring out the best parameters for a particular job… We have
cast items all the way down to a flask temp of 500oF . When you have
to cast thick and thin parts by the oven load, it becomes critical
to set up a reference chart ,or a book with pictures/model numbers
and record the best oven and metal temperature for most items …
this makes it far less tricky when we receive new pieces to
cast…99 % of the time we can nail the temperatures of a particular
new item first time out.

The temperatures you are using sound correct to me in relationship
to the thickness of your designs.I wouldn’t change anything if it’s
working! Best wishes Daniel Grandi

We do casting/finishing for designers and people in the trade.