Castable refractory curing and drying procedure?

[galadduin]

I'll be building a top loading raku and porcelain propane kiln for my and mom's ceramic projects. I'll be using castable refractory cement with high alumina. I've got a usage manual from the refractory company, the correct procedure is after drying the cement about 48 hours, the first drying and firing waaaay too long. Guide says I have to go up 150 C in 6-8 hours and keep at that temp about 12 hours, then in 12 hours I have to go up to 550C and hold there about 1 hour for every 1" thickness. Then to the working temp I'll be heating 100C per hour and hold it about an hour also.

This procedure is inapplicable for me. It needs about 2 or 3 days of continuous firing, that means 2 sleepless nights, tonnes of propane, this is not possible at all .. What if I don't follow this procedure, I didn't use castable refractory before but I read many people just wait it to be dried then fires it up that's all. The company manual says if you dont follow the procedure the resulting insulation will face leaks because of cracks and says we cannot be held of responsible of mis-drying blah-blah...

So do I simply ignore what do they say???

 

[mete]

Ceramics do not like thermal shock or thermal fatigue !! The basics of clay is that there is free water [48 hour drying] then there is chemically bonded water which must be baked out slowly. Too fast and that water turns to large amounts of steam which can crack the ceramic.
Your mom's projects will be done the same way , that's ceramics ! !

 

[galadduin]

Ceramics do not like thermal shock or thermal fatigue !! The basics of clay is that there is free water [48 hour drying] then there is chemically bonded water which must be baked out slowly. Too fast and that water turns to large amounts of steam which can crack the ceramic.
Your mom's projects will be done the same way , that's ceramics ! !

For a year we are making ceramics also in our electric kiln, we go up to 1200 C and even thin stoneware pieces goes up to 150 C in 4 hours then goes to 1200C straightly. Kiln goes to that temp in about 2-3 hours. We didn't experienced even one crack whatsoever. So if this castable cement is something like ceramics I guess I can deal with that. Slow and even drying about in 1 week is what is done for porcelain vessels, then it is very stable to faster heating procedure...

 

[SteelSlaver]

I would a small hand held torch and convert it over to connect to a real bottle. They sell a hose for this and things like lanterns. Use it to slowly heat your forge and keep turning it up. You should be able to do this without a lot of propane or watching. I would thing time is more critical than exact temps and steps.