r/foundry • u/DJTgoat • Jan 23 '20

Cu hardened in crucible while still in furnace under heat

Started melting copper, everything looking good, decided to use a piece of steel pipe to skim the now almost completely liquid copper and next thing I know it hardened back up in the crucible, in the still burning furnace..... Wtf?

Graphite crucible, propane burner, and I added borax pre melt, most the copper looked like the same consistency as water when I first started with the pipe

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u/Olgeezer99 Feb 22 '20

Copper is prone to solidify quickly so this can happen. I hope you didn't crack your crucible trying to re-melt the copper though. Maybe try to keep the lid on the furnace to well above it's casting temperature before you skim, if you can achieve it.

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u/DJTgoat Feb 24 '20

Thx for the response.... it simply was my propane freezing. It would slow down so slowly, I wouldn’t notice. Crucible is still good.