Burn Out: Once the plaster has set up, I try to let the "tank" air cure for several hours before placing it in the burn-out kiln, to allow some more of the water content to exit the casing. Then, on goes the kiln for 8 to 14 hours to cure the plaster fully and burn out the wax. This is how "lost wax" casting got its name, as the wax is totally burned away, right down to the last carbon molecule.
The tank also needs to be within a few hundred degrees of the metal I'm due to pour into it so as to allow an nice even flow through the now empty investment. If the investment is too cold, metal can cool too quickly and not fill the whole tree, which of course would SUCK.
Conversely, if the mold is too hot during pouring, the metal may stay liquid too long and venting gasses can collect, causing porosity and loss of surface detail which would also suck mightily. So, you see, metal casting (particularly bronze) isn't so much the quest to create art so much as the struggle to avoid suck-age.
Casting: Speak of the Devil. Once the burn-out cycle has finished, my Trolls & I don our protective gear and cook things up a bit. Bronze melts around 1600F degrees, so you can imagine that one tends to be cautious about not frying oneself.
My melting furnace is pretty small, allowing me to melt about 30 lbs of metal at one time, but lifting a crucible of molten metal always feels heavier than it is. We pull the tanks hot from the kiln and pour them fairly quickly (to avoid excessive cooling), careful to keep slag and plaster particles out of the investment.
Once poured, the tanks can sit for up to 3 hours before they're safe to knock about or move.
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Method to the Madness 
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