Firebrick furnace

[Bentiron1946]

I did mostly bronze. I had three different furnaces, one each for bronze, aluminium and brass. These furnaces are fairly cheap to build and I never mix metals in crucibles or furnaces, some do but I don't as I don't want any contaminates from other metals. I think this furnace could do cast iron but I have never tried it. There are plans on the internet for cupolas. If I want to do a cast iron project I usually go to one of the college iron pours. I only have a small furnace now with a cast lining in a 5 gallon bucket which is good for now.

[Ian]

I'd suggest looking closely at what you want from your furnace. For a one or two melt deal you can use those very lightweight building blocks that are made from ash. They can be carved using woodworking tools and will melt silver easily with a reil burner (I've done it myself) or I'd suggest using the light weight refractory bricks and (or) Kaowool in an old helium tank or such. The heavy refractory bricks absorb tremendous amounts of heat before throwing it back into the furnace, whereas the lightweight stuff tends to reflect the heat, much more efficiently. My final furnace for silver used a precast 'tube' of heavy refractory about 1/2 inch thick painted with ITC100 (an ceramic based paste/paint thats an excellent infra red reflector) that was surrounded by 4 inches of kaowool, inside an old helium tank. The lid was half filled with kaowool, then meshed and covered with heavy castable refractory. It got up to melting temps in 5 to 10 minutes and apart from where the reil burner went in and the flame came out the rest of the tank remained cool enough to touch even after a few hours of running.