Insulating firebrick
I am in the process of making my own insulating firebrick at about 1/8th the price of manufactured ones. I have the formula worked out and will be using some local Idaho fireclay for the bricks.
Currently I am building a brick press that will press the bricks to the size I want using the damp powder method. The press is base on the CINVA ram press designed for blocks used in construction in third world countries in the late 1950’s. I am resizing the chamber and adjusting the other mechanical pieces to work with the new size. When I get it all worked out and tested I will probably sell ready made plans for others who want to do it themselves.