I have a question regarding graphite crucibles. I bought a Kerr
Electro-Melt to melt the metal for my casting projects. It uses
graphite crucibles and I’m not sure if I am supposed to be using flux
or not. Am I supposed to flux the metal when I am melting it, or is
it OK to use graphite crucibles without it? If I need flux, do I coat
the whole crucible in flux first, or do I just sprinkle some in on
top of the metal right before I cast? Any help from anyone with
experience using the same type of Electro-Melt would be appreciated.
Jim Manners
Dear Jim,
The electro melt is a great tool. Just add a pinch of flux every
time you cast. I have never tried to line them. Keep track of your
melt temperature so every time you cast you can duplicate success.
Each metal will have it’s own casting temperature. Each metal should
have it’s own crucible. Sterling for one, white gold for another and
yellow gold for another. I do prefer to spin cast all white gold. If
you forget about the melt and fry the unit (I have once) the inner
element can be replaced. I keep a spare around just in case. The
first melt should be about twenty minutes. The following casts take
about ten minutes unless you are melting pounds of metal.
Good Luck,
Todd Hawkinson
While there’s no law against using flux with an electromelt, you
don’t usually need it. at most, I might add a pinch of boric acid to
the metal just before casting, if it doesn’t seem clear and clean
enough. Usually this will be with metals like bronze or the like, not
silver or gold. The problem with fluxes porecisly that they DO coat
the crucible. Graphite forms a nicely reducing atmospher around the
metal, and since the electromelt covers the crucible in melting,
there’s little or no oxygen in the atmosphere above the metal, since
the carbon in the graphite will have reacted with it to carbon
dioxide. so normally there should be no oxides needing to be
dissolved by flux. And gobs of flux sticking to the graphite just
tend to trap bits of metal, so then you’ve got a crucible that can’t
be used for other alloys.
Peter
Jim and Todd, Do not add flux to the melt in an Electro-melt. The
instructions for the unit specifically state not to do this. There
are several reasons for not adding flux in an electro-melt. You will
cost yourself more in repairs for one thing.
Ken Kotoski
MPG Repair
www.mpgrepair.com
1-877-262-2185
Dear Ken,
I have been using an Electro-Melt for over twenty years this way. A
small pinch of 20 Mule Team Borax has worked like a charm for all
that time. Both Sterling and all yellow Golds work the best. I always
spin all white golds. I have cast as much as twenty five pounds of
gold a month with very few problems. The repair was done after I
forgot about a melt for about fourty minutes one time (left on high)
and the element on the unit burnt out. The element was fairly easy to
replace. I’ve also used the same unit for twenty years with no
problems.
Best Regards,
Todd Hawkinson