Heres the question. I am wanting to coat the floor of my gas forge with mizzou(or bubble alumina) but really dont want to take the whole lining out to put in brand new bricks. Two of the bricks have a thin skim of flux/molten slag on them. Would it hurt to cover right over that with a thick coat of mizzou? Would the mizzou take? My forge has ceramic insboard in it and that stuff can get kinda "delicate" after its been fired for a while. So I hate to take it out and risk breaking it. Will I have to or will the mizzou be alright over the already used floor?

I think it would work; I did something similar on my propane forge. I used a soft firebrick for the floor and set it in and covered it with Mizzou.The Mizzou seems to have a different thermal mass but once up to heat should work, as mine works ok though probably at less efficiency. I have a used Valley forge that has a similar issue to yours....I scraped out all the old flux and slag I could and am thinking about whether to try to fill in or not. Try it and let us know how it worked.

Can`t you just carefully pull and flip the bricks?