Vince Pitelka on fri 2 jun 06
> I was thinking that he was
> using hard brick mixed in with soft in the same wall
> " same wall is key here Vince. Do you recommend mixing hard and soft
> brick in the same wall? Mike Gordon
Mike -
Back when we were experimenting with softbrick soda kilns, the inside layer
was softbrick, but there was hardbrick lining the firebox and around the
charging ports, the flue, the spyholes, and the door opening. These kilns
all failed too soon, because there is no way to adequately protect the
softbrick from the soda, but the failure was not due to an incompatibility
between softbrick and hardbrick.
One thing I have noticed - when building a softbrick kiln, there is no need
to leave expansion joints, because the brick naturally "give" a bit on the
edges when expansion takes place. That is not the case with hardbrick -
when it expands, it can break weld joints. The solution is to simply leave
a few small spaces (less than 1/8") on any course that is all hardbrick.
After the kiln is fired the first time, the gaps can be sealed on the
outside with a fireclay mortar. In the kiln you are rebuilding, perhaps
there were no expansion joints left in course of bricks that was mostly
hardbricks. That could cause serious degradation of the softbrick.
I don't like using springs to allow expansion on kilns. It leaves too much
flex in the frame, and that itself can cause degradation of the brick. I
like leaving expansion joints on hardbrick kilns, and then welding a VERY
heavy rigid frame.
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Mike Gordon on fri 2 jun 06
I was thinking that he was
using hard brick mixed in with soft in the same wall
" same wall is key here Vince. Do you recommend mixing hard and soft
brick in the same wall? Mike Gordon
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