Most artists and potters want some sort of visual variegation in their glazes. The mug on the right demonstrates several types. Opacity variation with thickness: The outer blue varies (breaks) to brown on the edges of contours where the glaze layer is thinner. Phase changes: The rutile blue color swirls within because of phase changes within the glass (zones of differing chemistry). Crystallization: The inside glaze is normally a clear amber transparent, but because these were slow cooling in the firing, iron in the glass has crystallized on the surface. Clay color: The mugs are made from a brown clay, the iron within it is bleeding into the blue and amplifying color change on thin sections.
Glossary |
Reactive Glazes
In ceramics, reactive glazes have variegated surfaces that are a product of more melt fluidity and the presence of opacifiers, crystallizers and phase changers. |
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Glossary |
Crystallization
Ceramic glazes form crystals on cooling if the chemistry is right and the rate of cool is slow enough to permit molecular movement to the preferred orientation. |
Glossary |
Breaking Glaze
A decorative effect in ceramic glazes that exploits changes in color and character in certain glazes when their thickness varies. |
Glossary |
Opacifier
Glaze opacity refers to the degree to which it is opaque. There is more than meets to eye to the subject of opacity control. |
Glossary |
Phase change
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