NEVER use cheap crucibles for cast iron !!!

I tried to cast iron, I still had an old crucible somewhat worn out from earlier melts of cast iron, so this should be its last use.
I melted it and heated to 1400 C in a forced draft propane furnace but when I wanted to take the crucible out, it was softened and cracked so I did not want to pour, but it was already too late. Iron was leaking out of the bottom, but it stopped due to freezing.
I dumped the hot crucible with the frozen iron into a bucket of water and then I shattered the crucible, so I could reclaim the bum of cast iron.
So I have to repair the furnace and I've learned a lesson. It was a cheap Amazon crucible. Suitable for copper alloys, but ferrous is a no-no.

I'll only use the real Morgan Salamander crucibles, I already have two and one on order.
Here a short clip what I saw after shutting down the furnace and opening the lid.

https://www.metallab.net/jwplayer/video.php?f=/forums/requiem-for-a-crucible.mp4

 

That just ruins the day, huh.

 

Scary experience.

I'd like to do some iron casting one of these days. Interesting that you got it melted in a propane furnace I had heard that might be harder to do.

Which site do you get the crucibles from?

 

I got this crappy (for cast iron, for cuprous it is OK) crucible from Amazon, but now I got a Salamander from cooksongold.com.
In a propane furnace I get cast iron melted and to 1400 C, but I used forced air, which makes it hotter. In the meantime I repaired the furnace by removing the frozen leaked iron and re-lining it with Kaowool and then painting it with Fermit.

 

If you have a decent sized cylinder to resist freezing from the higher flow rate, propane is the easiest fuel to melt iron. Propane being already in gaseous form burns fast enough to be tolerant of smaller furnaces.

 

One of these days I'm going to get around to making a functional oil burner with a nice pressurized oil pump system. I do like propane since it burns so easily and isn't messy but the heat that seems to come from oil is pretty inspiring. Thanks for the link. I need to pour a replacement for my iron fire pit grate as the old one cracked and broke.