Since I had a limited supply of castable, I decided to do a "hybrid" forge.....used 1" of #8 density kawool next the shell, and used the castable for everything inward from there....
5 bags of Mizzou 3000F castable later......
Now to leave it alone for about 2 weeks.....then try to take the forms out. After that I suspect it will be a month or so before it will be cured enough for some firings.
The down side to a forge like this is that amount of time it takes from beginning the build, to being able to use it, but experience has taught me that curing any type of refractory and/or coating is best done naturally. Otherwise the life of the material is dramatically reduced. Hopefully once this forge is cured and ready to use, it will last for several years, versus having to reline the kawool welding forge every 2-3 months as before.....and having to make repairs in between.