Maybe that is because you don't need a button. A button is a total waste of metal, take a look at the physics. It does not increase pressure on the casting and by the time the button is filling the casting is already solidified so it does not provide shrink filling ability.
How long does it actually take for silver to solidify after pouring?
(vacuum casting, electromelt for melting) I’m mostly self-taught,
having learned only a little on how to use the equipment from the
woman from whom it was bought. She told us to run the vacuum until
the visible metal in the casting, button or tree, begins to darken,
to make sure the metal is solidified. I suspect it solidifies much
faster than that, but of course I can’t see it to tell. What’s the
actual time frame for the metal to freeze after pouring?
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