Aebersold, Jane F. on tue 27 apr 04
>Will have to --bisque-- with a Propane updraft.
>--This is a large terra cotta garden pot. Coiled with 1 in diameter
coils with a wicked 2 in rim. Pot stands >over waist high.
>Worked on a slow dry. Let's say it's dry.
>1) Fear the pots gonna blow up. How do I slow this bisque down
>especially since the gas comes up to temperature rather quickly??
>Thank you.
>Joe
Hi Joe,
I routinely bisque large coil pots--54"-64" H--in an updraft Alpine,
fired with natural gas, forced air burners. I'm not sure what you mean
about the gas coming up to temperature rather quickly. My process is:
in the late afternoon, turn on one burner as low as you can get it
without it burning back in the burner--you'll need to adjust the air
appropriately at the same time. I set my damper at 1 and 1/2" and if
the piece is really large I leave the door cracked. The next morning I
turn the same burner up slightly, adjust air accordingly, close the door
if it is open. Late afternoon or early evening I turn on the other
burner, very low, asjust air and open the damper to 2". The next morning
I begin to fire it off. I have a pyrometer so that I can gauge the temp
rise rate. As you can see, the whole key is slow, slow, slow. If you
aren't sure the pot is dry to start with, you can slow that beginning
stage even more--i.e., start with one burner in the morning, don't turn
it up until the next morning, etc. You might want to put a good layer
of grog under the piece so that it will be able to move as it shrinks.
I find that the weight on the bottom is more of a problem than the
firing.
Hope this helps,
Regards, Jane
Jane Aebersold
University of Oklahoma
jane@ou.edu
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