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These bowls are fired at cone 03. They are made from 80 Redart, 20 Ball clay. The glazes are (left to right) G1916J (Frit 3195 85, EPK 15), G191Q (Frit 3195 65, Frit 3110 20, EPK 15) and G1916T (Frit 3195 65, Frit 3249 20, EPK 15). The latter is the most transparent and brilliant, even though that frit has high MgO. The center one has a higher expansion (because of the Frit 3110) and the right one a lower expansion (because of the Frit 3249). Yet all of them survived a 300F to icewater IWCT test without crazing. This is a testament to the utility of Redart at low temperatures. A white body done at the same time crazed the left two.
Materials |
Redart
The most common commercially 200 mesh available raw terra cotta clay in North America. It fires red, has low plasticity and matures a low kiln temperatures. |
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Materials |
Ferro Frit 3110
High sodium, high thermal expansion low boron frit. A super-feldspar in clay bodies. Melts a very low temperatures. |
Materials |
Ferro Frit 3195
A commonly used boron frit, it is a balanced glaze all along at cone 06-02 (with the addition of 10-15% kaolin). Not fully glossy. |
Tests |
Boiling Water:Ice Water Glaze Fit Test
Ceramic glazes that do not fit the body often do not craze until later. This test stresses the fit, thus revealing if it is likely to craze later. |
Tests |
300F:Ice Water Crazing Test
Ceramic glazes that do not fit the body often do not craze until later. This progressively stresses the fit until failure point, thus giving it a score |
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