Arnold Howard on sun 1 aug 99
Judy mentioned an uneven kiln bottom with cracked cement and wondered
about placing a kiln shelf over the bottom.
1. Have you tried reversing the brick bottom? You will need to turn the
kiln upside down to do that. Vacuum the kiln first so kiln wash will
not fall into the brick grooves.
2. If you place a shelf on the kiln bottom, the bottom will fire
cooler, because the shelf will increase heat needed for that area.
3. The cement on the bottom cracked because it is of a different
coefficent of expansion than the firebrick. In the future, mix the
cement half and half with firebrick powder.
What experiences have other Clayart members had in reversing the brick
bottom or repairing firebrick with cement mixed with firebrick grog?
Arnold Howard
--- Judy Frederick wrote:
The way she handled this problem was to
> apply a layer of kiln cement
> to the bottom of the kiln, (not the shelf thought,
> thank goodness [only one
> shelf]).
> The problem is the kiln cement has cracks that are
> buckling and the bottom of
> the kiln is no longer flat. Hence the question, (I
> am able to take the
> bottom out of the kiln) what is the best way to
> either remove some or all of
> this or smooth out the cracks without having the
> same results later?
> Another question ... should I be using a kiln shelf
> on the bottom as well?
> She put her pieces right on the bottom of the kiln?
> I guess she did not want
> to buy a second shelf, which would have made the
> first problem nonexistent,
> but what's done is done now.
> TIA Judy
>
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Bobbi Bassett on sun 8 aug 99
In a message dated 8/2/99 12:34:30 AM Eastern Daylight Time,
ajhparagon@yahoo.com writes:
> 2. If you place a shelf on the kiln bottom, the bottom will fire
> cooler, because the shelf will increase heat needed for that area.
I have used a shelf (an old cracked one) on the bottom for over 20 years. I
always seem to have oxided pieces or others that don't object to being fired
at a bit lower temp to put on the bottom. The advantage is that the bottom of
one 15 year old kiln is still smooth and functioning well with the original
old shelf on it. Just my two cents worth................
Bobbi in PA
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