Permanent Molds for Gray Iron?

[maquiza]

Hello to all,
I am already casting aluminum with permanent molds, but I want to know how to use permanent molds for gray iron.
What is the material for the mold and if it needs a special coating, and things like that.

Thank You,

[CBNDude]

We use a furan resin bonded sand coated with a ceramic mold wash.