ThePottery@AOL.COM on wed 6 sep 00
I have found that most of my warpage problems do not come from the firing but
are due to uneven drying of the clay from forming to dry green ware state.
Many times I have covered a table of drying pots with an old sheet to take
care of drafts. On special pots, such as wide rimed platters, as soon as I
can turn them over I cover them with three layers of newspaper making sure
that no drafts can get to the clay. Slow drying but it has completely
eliminated any warpage if the foot is on a flat surface in the firing. I
have had new 1" 12 X 24" shelves cut into 12X12 squares and sit the small
shelf on top of the warped shelf and the platter on that. Well worth the
cost as apposed to getting a very expensive warped platter out of the firing.
Tracy
Jean Corll on wed 6 sep 00
I make stoneware flat pcs., e.g. Christmas ornaments and switch
plates. I have an old electric kiln with switches that I can control
fairly well, even though I can't make use of 1/3 of the kiln. I also
now have Paragon's new hi-fire electronic pottery kiln. No matter what
I can "think" of to do, the warpage is terrible in comparison to the
other kiln! I have slowed the firing down to 150 degrees per hours, put
on hold through temps of 975 - 1075, and also tried assorted cone
firings. I am disabled and thought this kiln would be convenient for
me. If anyone has experience with flat pieces in electric kilns, I
would appreciate your help. I have filled a legal tablet with ideas
that haven't worked.
Jean Corll
jeancorll@earthlink.net PH & FX 330-7998209
Paul Gerhold on thu 7 sep 00
The problem may be in your clay body. My wife and I are primarily Raku
potters who use electric kilns. From your letter it sounds like your work
doesn`t have to hold water so you might want to try a body with more grog or
kyanite. In my experience playing with developing bodies I have found that
adding about 5% medium grog or 38 mesh kyanite can really help warping. The
other critical element to controlling warping seems ( at least in my
experience ) to be drying. Going back to bodies for a moment you might want
to try a body like Standard 295 or similar. This body will get very strong at
cone 5 or 6 . When I was using their body I bisqued at 04 and it still took
the glaze well. If these ideas don`t help you can always write me at
PGerhold@AOL.com. Good potting.
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