vince pitelka on wed 20 nov 02
> It has been mentioned to me that warping of the ware during a glaze
firing is
> linked not to drying of the pieces or clay memory, but is in fact linked
to firing
> the ware too fast in the glaze firing.
Meagan -
Did someone on Clayart actually say that fast firing is the only or primary
cause of warping? I have never heard of such a thing. It makes no sense at
all.
Firing excessively fast could cause warping, especially if the wares are
close to the heat source, but it is certainly a minor cause of warping. The
most common causes of warping are 1) uneven support of wares in the firing,
2) overfiring of a claybody, causing it to become excessively pyroplastic,
and 3) clay memory from forming and drying, leaving stress zones in the
wares which "relieve" themselves in the firing, causing serious warping.
The importance of the latter cannot be overstated. There are so many things
people do to leave undesirable clay memory in the wares - stresses which are
stored in the rigid unfired clay, but which cause the clay to move around
once it becomes pyroplastic in the firing.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://iweb.tntech.edu/wpitelka/
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