Earl Brunner on thu 4 nov 99
Thanks to the many who have sent thoughts/ideas on the problem. Many did
not post to the list. Many others indicated similar problems and
expressed an interest in what I found out.
I would like to summarize.
clay preparation: If wedging in such a way that a spiral is wedged into
the clay then turn the piece of clay on the wheel head so that the
spiral is continued in the throwing process. Grog or fiber glass in the
clay for strength. Compress well, keep the bottom as dry as possible
during forming.
drying: dry thoroughly, upside down if possible, some turn the pot
upside down and cover the sides so that the bottom can dry first.
firing bisque: Slow enough heat climb below the boiling point to drive
the moisture out and a fairly slow climb through the chemical water
temperatures. Sand, wads of clay (sometimes dusted in alumina) even
pieces of fiber blanket used to lift the piece off the shelf and allow
air under and the piece to move on the shelf. Larger pieces higher in
the kiln.
glaze fire: Sand, wads of clay (sometimes dusted in alumina) even
pieces of fiber blanket used to lift the piece off the shelf and allow
air under and the piece to move on the shelf
I have given this some more thought and one of the problems I think I
have is the efficiency of the kiln. I have a Geil fiber down draft
kiln. The pilots alone will get the kiln over 800 degrees over several
hours. To keep it from getting too hot to fast I have to keep the door
cracked open and gradually close it. Up until I close the door the kiln
functions essentially as an updraft. At the point that I finally close
the door, the flow abruptly changes to down draft and heat is suddenly
forced to the bottom of the kiln. Some of my problem probably centers
around this part of my firing. I am going to have to take this early
part slower with larger pots. And it makes sense to have them higher in
the kiln.
Any way, thanks for all the input everyone.
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
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