I just bought my first gas forge, a single burner BECMA. It’s insulated with untreated/coated ceramic board. The instruction say to open the doors and heat it up slowly/carefully and the allow it to cool a couple of times before actually using the forge to heat metal. It says nothing about rigidizer or ITC or any other treatment. 

I already have some rigidizer and ITC, so my question is, do I treat the inside of the forge before or after «breaking it in» with the careful initial firing, or does it make no difference?

Rigidizer is of small value on ceramic board, but a good surface coating has a of a lot of value. Plistex is good the board and plenty cheap.

Thank you.