kiln lid material

[jerry keller]

I'm building a bigger, better, faster kiln, and am taking stock on some of the materials. The walls and floor are brick, and the lid is a ceramic composite board called M board. On the inside of this is a layer of refrasil, Irish Linen, and then there will be 6 elements hanging from the lid.
When placing the refrasil into the angle iron frame yesterday, I noticed it was not as big as I had wanted....there was just a slight overap after the M board, and it did not tuck into the angle iron more than an inch or so.
I put some white syrupy kiln repairing material onto the refrasil, and hope it will let the refrasil stay in place. Any suggestions on attaching refrasil to either the M board, or the angle iron?
Also, when placing the M board, which was in two pieces, into the lid, a chunk of the material broke. It was a 2 inch board, and at this seam, it was cut to 1 inch on the top, and 1 inch on the bottom, to lay into each other. The bottom piece is intact, and I put the top "crumbs" back in place. Seeing as this is my only insulation, other than the refrasil, in the lid, should I start with another piece, or is there a better material for the lid that I should use instead? Or will the damage not hurt the overall needs of the kiln.
First time kiln builder, Jerry

[Bert Weiss]

I'm building a bigger, better, faster kiln, and am taking stock on some of the materials. The walls and floor are brick, and the lid is a ceramic composite board called M board. On the inside of this is a layer of refrasil, Irish Linen, and then there will be 6 elements hanging from the lid.
When placing the refrasil into the angle iron frame yesterday, I noticed it was not as big as I had wanted....there was just a slight overap after the M board, and it did not tuck into the angle iron more than an inch or so.
I put some white syrupy kiln repairing material onto the refrasil, and hope it will let the refrasil stay in place. Any suggestions on attaching refrasil to either the M board, or the angle iron?
Also, when placing the M board, which was in two pieces, into the lid, a chunk of the material broke. It was a 2 inch board, and at this seam, it was cut to 1 inch on the top, and 1 inch on the bottom, to lay into each other. The bottom piece is intact, and I put the top "crumbs" back in place. Seeing as this is my only insulation, other than the refrasil, in the lid, should I start with another piece, or is there a better material for the lid that I should use instead? Or will the damage not hurt the overall needs of the kiln.
First time kiln builder, Jerry

Jerry

I have never worked with any of the materials you are using (except brick). The insulation that I recommend is 1" Unifrax HD board backed up with 4" of monoblock mineral wool or 4" of duraback blanket in the walls and 2" backup in the walls. The mineral wool is cheaper and better insulation. My insulation is held up with Unifrax insultwist studs. It has never shed a particle, nor has it sagged in 13 years of regular use, and there are seams.

The only reason I can think of to use brick for kiln walls is in a glass blower's annealer. The reason being that the brick will hold heat when the door is opened to place more work. For fusers, I think brick is a lousy choice. The reason the kiln companies use it is 2 fold. They know how to because they have been in the brick pottery kiln business for at least most of the last century. And, they don't have to issue a cancer disclaimer because some rats got cancer when alumino-silicate fibers were surgically placed in their lungs.

Sorry to be negative about your choices, but that is how I call it. Homemade kilns can be far superior to the standard store bought units in my opinion (and experience). Not to mention cost effective to build and use.

[Brock]

I don't think that slight damage to the join of your M board is significant. For attaching the Refrasil, can you use high temp wire? Make U's of Nichrome or Kanthal and pierce the Refrasil, then attach the open ends of the U's to your angle iron, or expanded metal mesh, or whatever backs your M board. Brock