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Here is an example of how a cast porcelain piece, L3778G, warps during the glaze firing. Several factors contribute to this failure:
-It is cast and the walls are very thin.
-This porcelain is highly vitreous.
-This shape has no inherent strength to resist rim warping.
The following would help:
-Switching to machine forming (which orients particles concentrically).
-Reduce the feldspar in the recipe (to reduce fired maturity).
-Fire lower.
-Cast thicker walls.
-Change to a more flared shape.
-One other option (borrowed from bone china): Fire the piece upside down on a custom alumina setter fitted to the final rim diameter - then clear glaze it at a lower temperature.
Troubles |
Warping
There are multiple reasons why pottery and porcelain pieces can warp during firing, both vitreous and non-vitreous ware. Here is what to do about it. |
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Glossary |
Vitrification
The term vitrified refers to the fired state of a piece of porcelain or stoneware. Vitrified ware has been fired high enough to impart a practical level of strength and durability for the intended purpose. |
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