In a nutshell:
*Took a ~1.5"x1.5" square of 1" thick alumina fibre mat (ceramic wool, inswool, durawool, kaowool, etc.)
*Mixed up a thick slip of fireclay (stir-able, but not quite pourable)
*Peeled the little cube into three layers and saturated each one with the clay slip
*Pressed the layers back together-- trying to force as much air out of the fibres, and as much slip in, as possible
*Formed the now 1.5"x1.5"x0.5" clay/fibre pad around a piece of 9/16" tubing, resulting in some what of a "C" shape (I did this because I wanted to fire the material with the fibres 'stressed' to see if they might spall or expand)
*Took the little C-brick off the form and allowed it to dry completely before firing it in a little 4" J-tube furnace I mocked up in the fireplace using kiln bricks, clay slip, and a piece of 4"x18" schedule 40 pipe (total riser height: 25")
*Burned it nice and hot for about two hours and then let little stove cool overnight before pulling off the riser and fishing out the sample
--Out came an extremely light, quite hard little specimen of a fairly durable material that has that "tink" sound that comes from a ton of trapped micro-airspace. The sharper edges of the "C" are not brittle and would probably survive some mild abuse. There was a slight amount of expansion, but nothing that would be of consequence in a fully formed and cast system.
The final intent is to be able to 'alumina-mache' a
cardboard form, let it harden, and then pack it into a larger form with clay/perlite/fiberglass mix, let that dry a bit and then burn out the cardboard core using a temporary riser that can be switched from on side to the other so that the
feed tube side will get hot
enough to harden completely. This will give me the ability to create a fire core with a more organic form and less right angles. I can't wait to hear what it will sound like when it burns...
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