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Flask temperature


#1

This is my first day as a member of the Orchid discussion group, and
I do not find a recent thread devoted to flask temperature (although
many were in past years).

I am getting ready to buy a home casting system, and I want to make
sure my decision is an informed one. (I mm presently using the
centrifugal system in the studio of my jewellry instructor.)

I have read a good number of the postings on flask temperature, but
still the picture is not perfectly clear. Why is it that I have been
able to cast a perfectly dense 3cm by 3cm by 3mm slab of silver with
raised initials (2 to 3 mm high) using a cuttlefish bone at ROOM
temperature, yet if I want to use a flask it should be seven or
eight hundred degrees Fahrenheit?? (None of the books I have
purchased address this topic.) There must be a simple answer, but I
cannot think of it.

By the way, the cuttlefish bone casting gave such a solid casting
that I do not believe that using a centrifugal cast could possibly
make it any more solid. This leads me to suspect that a vacuum
system should be just fine as far as density goes.

Stan Burris


#2

Cuttlefish bone is a light structure and absorbs little heat from
the metal. Casting investment, however, is denser and will take a
great deal of the heat from the molten material causing it to freeze
in the sprues.

You can cast with a small cold flask using steam - a highly exciting
and rather dangerous procedure that gives variable results - but not
with the large industry sized flasks.

Tony Konrath
www.goldandstone.com