An un-sealed ceramic blanket would give off dust, which would be a huge silicosis risk! Talk about killer pizza! Just Google silicosis and ceramic fiber blanket and you’ll see exactly why. If you want to use a ceramic blanket in reverse you would have to engineer it in reverse…basically find some way to attach blanket to inside wall (fire mortar maybe) and then build in backwards a firebrick wall (talk about challenging brickwork). Make sure to always use an N-95 grade mask when working with any insulation, but especially glass-based ones like a fiber blanket. Can’t repair lung damage.