Zang/Hoffman on thu 2 aug 01
The sidewall K-23 brick over (8 rows up) and around the target bricks of our
newish (20 cone 9/10 reduction firings) 60 cf kiln are shrinking (20%)
,crumbling, and breaking off in 1X4" chunks. The kiln manufacturer will
replace the brick, but nobody seems to have an explanation. The brick people
ran some tests and found an increased K in the fluxed brick, which I would
expect since it is the main flux in my glazes. We fire a normal nine hour
moderate reduction cycle. Any ideas?
iandol on sat 4 aug 01
Dear Znng/Hoffman,
You seem to be taking your RI 23 bricks over limit of their service =
range, which according to De Boos, Harrison and Smith, is 1260 degrees =
Celsius. I think it might be wiser for people who are intending staying =
in the high fire range to look to RI 26, with a max service temperature =
of 1425 Celsius if they are looking for extended maintenance free life =
out of a kiln. Yes, they are more expensive. But frequent replacement of =
the lower grade and disruption of production schedules may be more so.
Best regards,
Ivor Lewis. Redhill. South Australia.
DeBorah Goletz on sun 5 aug 01
Ceramic Industry ran an article a year or so ago about a kiln brick problem.
The jist of it was that the mud joints need to be large enough to
allow for brick expansion during firing - particularly in areas where the
flame hits directly.
If the joint is too small, the
brick is squeezed by its neighbor bricks during firing, causing its facing
side to crack or break away. This doesn't explain your brick shrinkage
though -
could be a manufacturing problem.
Best,
DeBorah Goletz
----------
>From: Automatic digest processor
>To: Recipients of CLAYART digests
>Subject: CLAYART Digest - 1 Aug 2001 to 2 Aug 2001 (#2001-214)
>Date: Fri, Aug 3, 2001, 12:00 AM
>
> Date: Thu, 2 Aug 2001 13:12:05 -0400
> From: Zang/Hoffman
> Subject: Crumbling Bricks
>
> The sidewall K-23 brick over (8 rows up) and around the target bricks of our
> newish (20 cone 9/10 reduction firings) 60 cf kiln are shrinking (20%)
> ,crumbling, and breaking off in 1X4" chunks. The kiln manufacturer will
> replace the brick, but nobody seems to have an explanation. The brick people
> ran some tests and found an increased K in the fluxed brick, which I would
> expect since it is the main flux in my glazes. We fire a normal nine hour
> moderate reduction cycle. Any ideas?
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