Vince Pitelka on mon 21 apr 08
Shane Mickey wrote:
"i just posted about this then read vinces last entry, one questions, if the
heat does build up to the critical level
what is to stop the cement board from poping? also even if the block are
facing upright wouldnt the edges pop
just like anyother concrete? seems like no matter which way they face if
heat does build up, BOOOM! i have
to admit i thought mels idea of expanded metal to be silly but it is a small
barrier of non explodable material that lets air escape. fiber board i am
not sold on either as it would likely crush and degrade after awhile.
just an extra 2 cents"
Shane -
Your questions are sound. I think we have established that if the
refractory floor is properly built, there is no way that enough heat could
get through to the concrete. But even if the floor has too little
insulating value, in all the years I have been involved in firing,
designing, and building kilns, the only time I have ever seen the concrete
explode is in a slab. The porosity of contemporary cinder block would
probably drastically reduce that possibility. Strange - the thing that
makes it risky to place contemporary cinder block with the holes facing
sideways also reduces the chances that it would blow up. I think that
cement board is pretty safe too, because it is so thin, and because it is
reinforced with fiberglass.
Mel has mentioned using expanded metal lath before, and it sounds like a
good idea. I have never done it on my kilns, and have never seen any
problems as a result of moisture in the floor, but it does makes sense as an
"air-space" to reduce direct heat transfer from the brick to the concrete.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
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