Stuart Altmann on thu 20 nov 97
If you have ever thrown a teapot spout whose end was not cut off straight
across the axis (or on which you have placed a mark near the end), you know
that after firing, the end of the spout will have rotated somewhat.
Experienced potters learn how much their clay rotates and compensate by
rotating the spout in the other direction when attaching it. What
determines the direction of rotation? Is this just the memory of an
elastic material? That is, is the clay just "unwinding," tending to go
back in the direction from which your throwing has pulled it?
Stuart Altmann
Louis Katz on fri 21 nov 97
Yes iis described as memory. I think of it as the relaxing of stress stored
from the throwing torpque.
Louis
Vince Pitelka on sat 22 nov 97
>Experienced potters learn how much their clay rotates and compensate by
>rotating the spout in the other direction when attaching it. What
>determines the direction of rotation? Is this just the memory of an
>elastic material? That is, is the clay just "unwinding," tending to go
>back in the direction from which your throwing has pulled it?
Actually, it is just the opposite. When it is high-fired, the spout tends
to turn FURTHER in the direction of the throwing spiral. In otherwords, if
the wheel is turning counter-clockwise, then the throwing spiral is
clockwise, and the spout will turn further clockwise. With an average
stoneware body, and with a spout thrown quite thin, extending out three or
four inches from a medium-size teapot, it seems that the offset must be
about 30 degrees in the counter-clockwise direction in order to come out
right. Of course, relying on averages will inevitably get you in trouble.
Everyone's clay, spout design, and throwing habits are different.
Experiment experiment experiment.
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
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